双组分调控系统1910HK/RR调控猪链球菌2型致病性研究
|
摘要
猪链球菌病是由猪链球菌(Streptococcus suis,S.suis)引起的一种当前严重危害我国养猪业的重要细菌性传染病。根据荚膜多糖抗原成分不同,猪链球菌分33个血清型(1-31、33、35型和1/2型)。其中猪链球菌2型(Streptococcus suis serotype 2,SS2)作为一种重要人畜共患传染病病原,不仅影响着养殖业的健康发展,还严重危害着人类的健康,引起了社会的高度关注。近几年,SS2已成为国内外研究的热点,尤其是关于其分子致病与免疫机理方面的研究。
病原微生物致病由多种毒力因子的协同作用而引起,这些毒力因子受某些调控系统的调控,形成一个复杂的调控网络。双组分调控系统(Two-Component Regulatory System,TCS)是广泛存在于细菌中的一种信号转导机制。它首先感应外界环境的变化,继而把信息传给内部系统,导致细菌毒力因子等表达发生变化。大量研究证实,TCS参与调控细菌致病性、生长代谢、营养代谢、耐药性及毒力因子的表达等多种生物学功能。随着我国猪链球2型05ZYH33和98HAH12菌株全基因组测序的完成,在SS2发现至少有15对双组分调控系统。然而,在这些调控系统仅SalK-SalR和两个“孤儿”调控因子RevS.CovR被研究报道。
本论文选取了其中一对双组分调控系统1910HK/RR为研究对象,开展了一系列生物学研究,以探讨其与SS2野生菌株SC19(WT)致病性的关系。主要研究内容包括：
1.基因缺失突变株Δ1910hk/rr和互补菌株CΔ1910hk/rr的构建及鉴定
参考SS2强致病株05ZYH33全基因组序列,设计引物,以四川分离的WT为亲本株,提取其基因组DNA为模板,PCR分别扩增基因1910hk/rr上下游同源臂、开放阅读框(ORF)和全长序列,利用温度敏感型“自杀性”质粒pSET4s,构建重组转移质粒pSET4s-1910hk/rr。将重组转移质粒电转化到WT感受态细胞中,通过28℃和37℃温度双标记和抗生素筛选,初步获得1910hk/rr基因缺失菌株。应用PCR、RT-PCR和测序对突变株进一步鉴定,成功构建基因缺失突变株Δ1910hk/rr。利用穿梭质粒pAT18,将所缺失的基因1910hk/rr及其启动子序列一起转入相应的基因缺失突变菌株Δ1910hk/rr中,通过PCR和RT-PCR鉴定,获得了相应的互补菌株CΔ1910hk/rr。
2.WT、Δ1910hk/rr和CΔ1910hk/rr的体外生物学特性比较研究
在体外相同培养条件下,开展了WT、Δ1910hk/rr和CΔ1910hk/rr体外生物学特性比较研究。结果表明：Δ1910hk/rr的生长速率要低于WT和CΔ1910hk/rr。透射电镜结果显示,Δ1910hk/rr形态结构未发生改变。定性和定量的溶血性试验结果表明,与WT相比,Δ1910hk/rr的细菌溶血活性并没有发生显著变化。中性粒细胞(PMN)介导的杀伤实验结果显示,双组分调控系统1910HK/RR缺失后使得SS2抵抗中性粒细胞(PMN)的杀伤能力降低。体外细胞粘附和侵染试验结果表明,Δ1910hk/rr对HEp-2细胞的粘附和侵染能力降低,但是粘附能力下降更为显著。
3.双组分1910HK/RR缺失后对SS2致病性的影响
为了进一步评价双组分调控系统1910HK/RR对SS2致病性的影响,在CD-1小鼠和断奶仔猪身上开展了动物实验。分别用菌株WT、Δ1910hk/rr和CΔ1910hk/rr感染CD-1小鼠。半数致死量(LD5o)结果为,Δ1910hk/rr为1.22×109CFU,而WT为4.14×107CFU野毒菌株,突变株是野生菌株的29.5倍,Δ1910hk/rr的毒力与WT相比下降非常显著。发病率和存活率试验：参考小鼠半数致死量的结果,采用了108CFU的剂量来进行试验。分别用Δ1910hk/rr、CΔ1910hk/rr和WT感染小鼠,观察12 d。其结果为：与WT相比,Δ1910hk/rr发病率降低,死亡率为10%,感染后小鼠脑和肺组织无明显的病理损伤。WT与CΔ1910hk/rr的死亡率分别为70%和80%。组织器官载菌量结果显示,Δ1910hk/rr感染组小鼠的心、肝、脾、肺、肾、脑、血等组织活菌数都要低于WT。进一步以105CFU剂量感染5周龄左右断奶仔猪。结果为：感染后48 h内WT组死亡率为66.7%(4/6)；存活的2头仔猪也出现典型的症状,而Δ1910hk/rr组观察到21d,死亡率为16.7%(1/6)：心、肝、脾、肺、肾、脑、血液、关节等组织载菌量比较分析发现,Δ1910hk/rr组也低于WT组。以上结果说明,双组分1910HK/RR缺失后SS2的致病性明显降低。
4.双组分调控系统1910HK/RR调控SS2致病性机制的初步研究
为了探讨双组分调控系统1910HK/RR调控SS2致病性的可能分子机制,首先,通过基因表达谱芯片片,开展了Δ1910hk/rr与WT差异表达基因分析。结果显示：在整个基因组2194个基因中,Δ1910hk/rr有219个基因转录水平发生了变化,占整个SS2基因组9.98%。其中105个基因下调表达1.5倍以上,114个基因上调1.5倍以上。有50个基因表达下调2倍以上,32个基因表达上调2倍以上。选取与氨基酸转运、代谢、毒力、荚膜合成等相关的24下调表达的基因进行荧光定量PCR验证,其结果也全部下调,证实了芯片结果的可信性。为了研究1910HK/RR与唾液酸合成相关的4个基因(NeuB.NeuC.NeuD.NeuA)的结合特性,克隆、表达并纯化双组分调控系统1910HK/RR的反应调控蛋白1910RR,经EMSA证实,唾液酸合成相关基因启动子能与1910RR结合,初步证实了唾液酸合成相关基因受1910HK/RR的调控。
Streptococcus suis serotype 2 (SS2) is one of the most important swine pathogens, and an emerging, life-threatening zoonotic agent in both pigs and humans. Based on the CPS antigens of S. suis,35 serotypes have been characterized. SS2 is most commonly and most virulent of these serotypes. SS2 cause great economic loss to the pig industry worldwide. Due to high economic losses as well as threat to human life, the study of SS2 pathogenesis, and the development of new vaccines is crucial for prevention and control of this disease.
Development of the disease requires temporal and coordinated expression of a series of genes that allow the prospective pathogen to shift to its pathogenic state and adapt to a hostile environment in the host. TCS control the expression of virulence factors in a wide range of bacterial species in response to external stimuli. For bacterial pathogens, they have evolved virulence factors and regulation systems that allow adaptation to different environments within a host ensuring their survival. TCS generally consist of a sensor kinase and response regulator and are the major means by which bacteria recognize and respond to a variety of environmental stimuli. Many results have implicated these systems as playing an important role in the regulation of a variety of essential processes including cell-cycle progression, pathogenicity, and development.
Two SS2 strains 05ZYH33 and 98HAH12 isolated in China have been sequenced. The results predict that there are 15 TCS in both the strains together with single, unpaired response regulator. To date, only the SalK/SalR system and two orphan response regulators, RevS and CovR.
In this work, we constructed a mutant strain of the TCS 1910HK/RR, designatedΔ1910hk/rr and measured its virulence in vitro and in vivo. So the following researches were explored.
1. Construction and verification of SS2 mutant strain (Δ1910hk/rr) and complementation strain (CΔ1910hk/rr)
The upstream and downstream flanking regions of 1910hk/rr were separately amplified fromSS 2 wild-type strain SC19 genomic (WT) DNA respectively. Followed by digestion with the corresponding restriction enzymes, the PCR products were directly cloned into a pSET4s vector. Then, the plasmid, pSET4s-1910hk/rr was electroporated into WT, and the resultant strains were grown at 28℃in the presence of spectinomycin (100μg/mL) selection and subsequently passaged at 37℃in the absence of spectinomycin selection as described previously. Successful deletion of the 1910hk/rr was confirmed by PCR and RT-PCR. For complementation analysis, a DNA fragment containing 1910hk/rr and its upstream promoter were amplified and cloned into the E.coli-S.suis shuttle vector pAT18. Then the recombinant plasmids were electrotransformed into the mutants to screen the complemented strains CΔ1910hk/rr.
2. Biology characteristic research of the SS2 mutant strainΔ1910hk/rr, complementation strain CΔ1910hk/rr and SS2 wild type srain (WT)
The results of the growth curve ofΔ1910hk/rr、CΔ1910hk/rr and WT showed thatΔ1910hk/rr grow slower than that of WT. The hemolytic activity of wild-type strain was more high higher than that of mutant strain. However, there were not significant difference-betweenΔ1910hk/rr and WT. The hemolytic activity of complementation strain was restored, and was about two times higher thanΔ1910hk/rr. But it did not reach the level of WT. To assess whether the lack of 1910HK/RR affected the cellular adhesion of SS2, the adherence efficiencies of the WT and theΔ1910hk/rr mutant to human continuous laryngeal epithelial cell line Hep-2 cells were compared. The results showed that WT showed significantly more adhesion to both Hep-2 cells than theΔ1910hk/rr, indicating the role of 1910HK/RR as an important mediator in the cellular-adhesion process. LD50 values were 4.14×107CFU for WT,1.22×109CFU forΔ1910hk/rr. Compared with parent strain,Δ1910hk/rr was attenuated 29.5 fold. The effect of 1910HK/RR on PMN killing was further examined. PMN were incubated with two strains for two hour and the bactericidal activity of PMN cells was determined. Remained bacteria were decreased in theΔ1910hk/rr group. In contrast, the WT strain still multiply when incubated with PMN, indicating that 1910HK/RR is able to enhance the bactericidal activity of PMN.
3. Impact of the 1910HK/RR on the virulence of SS2 WT
In order to evaluate whether the 1910HK/RR contributes to the virulence of SS2 in vivo, an experimental infection of CD-1 mice was performed. Morbidity and mortality analysis of CD-1 mice was performed to study pathogenesis of 1910HK/RR. Five-week-old CD-1 mice were intraperitoneally inoculated with 108 CFU/mL bacteria and the survival was monitored over a 12-day period. The results showed that almost all animals in the WT group presented severe clinical signs of sepsis, such as depression, rough hair coat, swollen eyes, weakness and prostration during the first three days post-infection. Seven mice died from septicemia in the WT group during 48 hour post-inoculation. In contrast, only one mice died in theΔ1910hk/rr group during the 48 hours post-inoculation and all of remaining nine mice did not present severe clinical signs of sepsis associated with SS2 infection during the trial, recovering after 4 days post-inoculation. In order to further confirm the clinical signs ofΔ1910hk/rr mutant in vivo, bacteria loads of organs were monitored. According to results above, mice were intraperitoneally inoculated with either the strainΔ1910hk/rr or WT at a dose of 1×107 CFU. Results showed that bacteria loads in blood following inoculation were lower in theΔ1910hk/rr group, suggesting that theΔ1910hk/rr could not multiply effectively in organs compared with WT.
The contribution of 1910HK/RR to SS2 virulence was assessed by infecting piglets with theΔ1910hk/rr mutant or WT strain. All six piglets inoculated intranasally with WT strain at the dose of 1×105 CFU developed hyperthermia and depression within 48 hours, including two of which that died withing 24 hours. Later, most of the typical disease symptoms, including limping, swollen joints, shivering, central nervous system failure and respiratory failure were observed. Four of six piglets (4/6) infected with WT strain died within 48 h post-infection. In contrast, none of the piglets infected with theΔ1910hk/rr developed any of the clinical signs mentioned above within the first 24 hours with exception of one which was slightly depressed. However, one piglet died within 48 hours. The remaining five recovered from fever showing none of other typical disease symptoms and remained healthy throughout the 21 day experiment. To better evaluate the virulence attenuation ofΔ1910hk/rr, colonization experiments and histopathological examinations were carried out. The results showed that almost all the bacterial counts recovered from different tissues ofΔ1910hk/rr mutant infected-piglets were significantly lower
compared with WT infected-piglets. Notably, the bacterial counts from theΔ1910hk/rr infected group was lower than WT. Histopathological examination of brain and lung tissues demonstrated that the blood vessels of brain from the WT infected group were filled with numerous macrophages and neutrophils compared to theΔ1910hk/rr infected group. In fact, the presence of high numbers of leukocytes suggests that the exacerbated inflammatory response might be the cause of death within the first 48 hours.
4. Role of 1910HK/RR in the virulence regulation of WT
To gain further insights into the network mediated by 1910HK/RR, DNA microassay, quantitative PCR was applied to reveal the differential transcription profiles between the strain WT with theΔ1910hk/rr independently. In this study we used a microarry which was made by using available the SS2 05ZYH33 strain whole genome sequence. To compare with the wild type SS2 strain SC19 gene expression,Δ1910hk/rr shows that 105 genes were down-regulated 1.5-fold and 114 genes were upregulated 1.5-fold. In total, the absence of 1910hk/rr led to changed expression of over 200 genes. Of the 114 upregulated genes,24 genes were investigated. They can be roughly categorized into the following four groups:(Ⅰ) Genes involved in ABC-type amino acid transport and metabolism; (Ⅱ) Genes involved in metabolism; (Ⅲ) Genes encoding membrane proteins and some proteins of unknown function, associted with virulence. (Ⅳ) Genes encoding sialic acid synthesis gene. The intereaction of DNA promoter with regulator 1910RR was confirmed by EMSA.
病原微生物致病由多种毒力因子的协同作用而引起,这些毒力因子受某些调控系统的调控,形成一个复杂的调控网络。双组分调控系统(Two-Component Regulatory System,TCS)是广泛存在于细菌中的一种信号转导机制。它首先感应外界环境的变化,继而把信息传给内部系统,导致细菌毒力因子等表达发生变化。大量研究证实,TCS参与调控细菌致病性、生长代谢、营养代谢、耐药性及毒力因子的表达等多种生物学功能。随着我国猪链球2型05ZYH33和98HAH12菌株全基因组测序的完成,在SS2发现至少有15对双组分调控系统。然而,在这些调控系统仅SalK-SalR和两个“孤儿”调控因子RevS.CovR被研究报道。
本论文选取了其中一对双组分调控系统1910HK/RR为研究对象,开展了一系列生物学研究,以探讨其与SS2野生菌株SC19(WT)致病性的关系。主要研究内容包括：
1.基因缺失突变株Δ1910hk/rr和互补菌株CΔ1910hk/rr的构建及鉴定
参考SS2强致病株05ZYH33全基因组序列,设计引物,以四川分离的WT为亲本株,提取其基因组DNA为模板,PCR分别扩增基因1910hk/rr上下游同源臂、开放阅读框(ORF)和全长序列,利用温度敏感型“自杀性”质粒pSET4s,构建重组转移质粒pSET4s-1910hk/rr。将重组转移质粒电转化到WT感受态细胞中,通过28℃和37℃温度双标记和抗生素筛选,初步获得1910hk/rr基因缺失菌株。应用PCR、RT-PCR和测序对突变株进一步鉴定,成功构建基因缺失突变株Δ1910hk/rr。利用穿梭质粒pAT18,将所缺失的基因1910hk/rr及其启动子序列一起转入相应的基因缺失突变菌株Δ1910hk/rr中,通过PCR和RT-PCR鉴定,获得了相应的互补菌株CΔ1910hk/rr。
2.WT、Δ1910hk/rr和CΔ1910hk/rr的体外生物学特性比较研究
在体外相同培养条件下,开展了WT、Δ1910hk/rr和CΔ1910hk/rr体外生物学特性比较研究。结果表明：Δ1910hk/rr的生长速率要低于WT和CΔ1910hk/rr。透射电镜结果显示,Δ1910hk/rr形态结构未发生改变。定性和定量的溶血性试验结果表明,与WT相比,Δ1910hk/rr的细菌溶血活性并没有发生显著变化。中性粒细胞(PMN)介导的杀伤实验结果显示,双组分调控系统1910HK/RR缺失后使得SS2抵抗中性粒细胞(PMN)的杀伤能力降低。体外细胞粘附和侵染试验结果表明,Δ1910hk/rr对HEp-2细胞的粘附和侵染能力降低,但是粘附能力下降更为显著。
3.双组分1910HK/RR缺失后对SS2致病性的影响
为了进一步评价双组分调控系统1910HK/RR对SS2致病性的影响,在CD-1小鼠和断奶仔猪身上开展了动物实验。分别用菌株WT、Δ1910hk/rr和CΔ1910hk/rr感染CD-1小鼠。半数致死量(LD5o)结果为,Δ1910hk/rr为1.22×109CFU,而WT为4.14×107CFU野毒菌株,突变株是野生菌株的29.5倍,Δ1910hk/rr的毒力与WT相比下降非常显著。发病率和存活率试验：参考小鼠半数致死量的结果,采用了108CFU的剂量来进行试验。分别用Δ1910hk/rr、CΔ1910hk/rr和WT感染小鼠,观察12 d。其结果为：与WT相比,Δ1910hk/rr发病率降低,死亡率为10%,感染后小鼠脑和肺组织无明显的病理损伤。WT与CΔ1910hk/rr的死亡率分别为70%和80%。组织器官载菌量结果显示,Δ1910hk/rr感染组小鼠的心、肝、脾、肺、肾、脑、血等组织活菌数都要低于WT。进一步以105CFU剂量感染5周龄左右断奶仔猪。结果为：感染后48 h内WT组死亡率为66.7%(4/6)；存活的2头仔猪也出现典型的症状,而Δ1910hk/rr组观察到21d,死亡率为16.7%(1/6)：心、肝、脾、肺、肾、脑、血液、关节等组织载菌量比较分析发现,Δ1910hk/rr组也低于WT组。以上结果说明,双组分1910HK/RR缺失后SS2的致病性明显降低。
4.双组分调控系统1910HK/RR调控SS2致病性机制的初步研究
为了探讨双组分调控系统1910HK/RR调控SS2致病性的可能分子机制,首先,通过基因表达谱芯片片,开展了Δ1910hk/rr与WT差异表达基因分析。结果显示：在整个基因组2194个基因中,Δ1910hk/rr有219个基因转录水平发生了变化,占整个SS2基因组9.98%。其中105个基因下调表达1.5倍以上,114个基因上调1.5倍以上。有50个基因表达下调2倍以上,32个基因表达上调2倍以上。选取与氨基酸转运、代谢、毒力、荚膜合成等相关的24下调表达的基因进行荧光定量PCR验证,其结果也全部下调,证实了芯片结果的可信性。为了研究1910HK/RR与唾液酸合成相关的4个基因(NeuB.NeuC.NeuD.NeuA)的结合特性,克隆、表达并纯化双组分调控系统1910HK/RR的反应调控蛋白1910RR,经EMSA证实,唾液酸合成相关基因启动子能与1910RR结合,初步证实了唾液酸合成相关基因受1910HK/RR的调控。
Streptococcus suis serotype 2 (SS2) is one of the most important swine pathogens, and an emerging, life-threatening zoonotic agent in both pigs and humans. Based on the CPS antigens of S. suis,35 serotypes have been characterized. SS2 is most commonly and most virulent of these serotypes. SS2 cause great economic loss to the pig industry worldwide. Due to high economic losses as well as threat to human life, the study of SS2 pathogenesis, and the development of new vaccines is crucial for prevention and control of this disease.
Development of the disease requires temporal and coordinated expression of a series of genes that allow the prospective pathogen to shift to its pathogenic state and adapt to a hostile environment in the host. TCS control the expression of virulence factors in a wide range of bacterial species in response to external stimuli. For bacterial pathogens, they have evolved virulence factors and regulation systems that allow adaptation to different environments within a host ensuring their survival. TCS generally consist of a sensor kinase and response regulator and are the major means by which bacteria recognize and respond to a variety of environmental stimuli. Many results have implicated these systems as playing an important role in the regulation of a variety of essential processes including cell-cycle progression, pathogenicity, and development.
Two SS2 strains 05ZYH33 and 98HAH12 isolated in China have been sequenced. The results predict that there are 15 TCS in both the strains together with single, unpaired response regulator. To date, only the SalK/SalR system and two orphan response regulators, RevS and CovR.
In this work, we constructed a mutant strain of the TCS 1910HK/RR, designatedΔ1910hk/rr and measured its virulence in vitro and in vivo. So the following researches were explored.
1. Construction and verification of SS2 mutant strain (Δ1910hk/rr) and complementation strain (CΔ1910hk/rr)
The upstream and downstream flanking regions of 1910hk/rr were separately amplified fromSS 2 wild-type strain SC19 genomic (WT) DNA respectively. Followed by digestion with the corresponding restriction enzymes, the PCR products were directly cloned into a pSET4s vector. Then, the plasmid, pSET4s-1910hk/rr was electroporated into WT, and the resultant strains were grown at 28℃in the presence of spectinomycin (100μg/mL) selection and subsequently passaged at 37℃in the absence of spectinomycin selection as described previously. Successful deletion of the 1910hk/rr was confirmed by PCR and RT-PCR. For complementation analysis, a DNA fragment containing 1910hk/rr and its upstream promoter were amplified and cloned into the E.coli-S.suis shuttle vector pAT18. Then the recombinant plasmids were electrotransformed into the mutants to screen the complemented strains CΔ1910hk/rr.
2. Biology characteristic research of the SS2 mutant strainΔ1910hk/rr, complementation strain CΔ1910hk/rr and SS2 wild type srain (WT)
The results of the growth curve ofΔ1910hk/rr、CΔ1910hk/rr and WT showed thatΔ1910hk/rr grow slower than that of WT. The hemolytic activity of wild-type strain was more high higher than that of mutant strain. However, there were not significant difference-betweenΔ1910hk/rr and WT. The hemolytic activity of complementation strain was restored, and was about two times higher thanΔ1910hk/rr. But it did not reach the level of WT. To assess whether the lack of 1910HK/RR affected the cellular adhesion of SS2, the adherence efficiencies of the WT and theΔ1910hk/rr mutant to human continuous laryngeal epithelial cell line Hep-2 cells were compared. The results showed that WT showed significantly more adhesion to both Hep-2 cells than theΔ1910hk/rr, indicating the role of 1910HK/RR as an important mediator in the cellular-adhesion process. LD50 values were 4.14×107CFU for WT,1.22×109CFU forΔ1910hk/rr. Compared with parent strain,Δ1910hk/rr was attenuated 29.5 fold. The effect of 1910HK/RR on PMN killing was further examined. PMN were incubated with two strains for two hour and the bactericidal activity of PMN cells was determined. Remained bacteria were decreased in theΔ1910hk/rr group. In contrast, the WT strain still multiply when incubated with PMN, indicating that 1910HK/RR is able to enhance the bactericidal activity of PMN.
3. Impact of the 1910HK/RR on the virulence of SS2 WT
In order to evaluate whether the 1910HK/RR contributes to the virulence of SS2 in vivo, an experimental infection of CD-1 mice was performed. Morbidity and mortality analysis of CD-1 mice was performed to study pathogenesis of 1910HK/RR. Five-week-old CD-1 mice were intraperitoneally inoculated with 108 CFU/mL bacteria and the survival was monitored over a 12-day period. The results showed that almost all animals in the WT group presented severe clinical signs of sepsis, such as depression, rough hair coat, swollen eyes, weakness and prostration during the first three days post-infection. Seven mice died from septicemia in the WT group during 48 hour post-inoculation. In contrast, only one mice died in theΔ1910hk/rr group during the 48 hours post-inoculation and all of remaining nine mice did not present severe clinical signs of sepsis associated with SS2 infection during the trial, recovering after 4 days post-inoculation. In order to further confirm the clinical signs ofΔ1910hk/rr mutant in vivo, bacteria loads of organs were monitored. According to results above, mice were intraperitoneally inoculated with either the strainΔ1910hk/rr or WT at a dose of 1×107 CFU. Results showed that bacteria loads in blood following inoculation were lower in theΔ1910hk/rr group, suggesting that theΔ1910hk/rr could not multiply effectively in organs compared with WT.
The contribution of 1910HK/RR to SS2 virulence was assessed by infecting piglets with theΔ1910hk/rr mutant or WT strain. All six piglets inoculated intranasally with WT strain at the dose of 1×105 CFU developed hyperthermia and depression within 48 hours, including two of which that died withing 24 hours. Later, most of the typical disease symptoms, including limping, swollen joints, shivering, central nervous system failure and respiratory failure were observed. Four of six piglets (4/6) infected with WT strain died within 48 h post-infection. In contrast, none of the piglets infected with theΔ1910hk/rr developed any of the clinical signs mentioned above within the first 24 hours with exception of one which was slightly depressed. However, one piglet died within 48 hours. The remaining five recovered from fever showing none of other typical disease symptoms and remained healthy throughout the 21 day experiment. To better evaluate the virulence attenuation ofΔ1910hk/rr, colonization experiments and histopathological examinations were carried out. The results showed that almost all the bacterial counts recovered from different tissues ofΔ1910hk/rr mutant infected-piglets were significantly lower
compared with WT infected-piglets. Notably, the bacterial counts from theΔ1910hk/rr infected group was lower than WT. Histopathological examination of brain and lung tissues demonstrated that the blood vessels of brain from the WT infected group were filled with numerous macrophages and neutrophils compared to theΔ1910hk/rr infected group. In fact, the presence of high numbers of leukocytes suggests that the exacerbated inflammatory response might be the cause of death within the first 48 hours.
4. Role of 1910HK/RR in the virulence regulation of WT
To gain further insights into the network mediated by 1910HK/RR, DNA microassay, quantitative PCR was applied to reveal the differential transcription profiles between the strain WT with theΔ1910hk/rr independently. In this study we used a microarry which was made by using available the SS2 05ZYH33 strain whole genome sequence. To compare with the wild type SS2 strain SC19 gene expression,Δ1910hk/rr shows that 105 genes were down-regulated 1.5-fold and 114 genes were upregulated 1.5-fold. In total, the absence of 1910hk/rr led to changed expression of over 200 genes. Of the 114 upregulated genes,24 genes were investigated. They can be roughly categorized into the following four groups:(Ⅰ) Genes involved in ABC-type amino acid transport and metabolism; (Ⅱ) Genes involved in metabolism; (Ⅲ) Genes encoding membrane proteins and some proteins of unknown function, associted with virulence. (Ⅳ) Genes encoding sialic acid synthesis gene. The intereaction of DNA promoter with regulator 1910RR was confirmed by EMSA.
引文
1. 陈国强,姚火春,陆承平.猪链球菌2型溶血毒素的产生条件及其特性分析.南京农业大学学报,2000,23(3)：71-75
2.胡丹.SS2荚膜缺失株的构建及其致病性研究.[博士学位论文].武汉：华中农业大学图书馆,2009
3.李明.信号转导系统SalK/SalR调控高致病性2型猪链球菌毒力的实验研究.[博士学位论文].武汉：华中农业大学图书馆,2008
4.娄素.恶臭假单胞菌CD2中双组分系统ColR-ColS调控机制的初步研究.[硕士学位论文].武汉：华中农业大学图书馆,2008
5.齐.猪链球菌2型毒力相关基因的研究.[博士学位论文].武汉：华中农业大学图书馆,2008
6. 黄友谊.结核分枝杆菌螺旋酶与DNA的相互作用研究.[博士学位论文].武汉：华中农业大学图书馆,2006
7.司有辉.谷氨酰胺合成酶GlnA及其转录调节因子GlnR对2型猪链球菌致病力影响的研究.[博士学位论文].武汉：华中农业大学图书馆,2009
8. 曾小涛,袁媛,郑玉玲,周冬生,姜永强,陈福生.SS2全基因组DNA芯片的研制及基因表达谱技术平台的建立.生物技术通讯.2009,20(5)：658-661
9. Anding Zhang, Bo Chen, Xiaofeng Mu, Yaxin Zhao, Pei Zheng, Huanchun Chen, Meilin Jin. Identication of three novel in vivo-induced expressed antigens during infection with Streptococcus suis serotype 2. FEMS Microbiol Lett 2009,295: 17-22
10. Allen A G, Lindsay H, Seilly D, Bolitho S, Peters S E, Maskell D J. Identification and characterisation of hyaluronate lyase from Streptococcus suis. Microb Pathog, 2004,36(6):327-335
11. Barrett J F, Goldschmidt R M, Lawrence L E, et al, Antibacterial agents that inhibit two-component signal transduction systems. PNAS,1998,95:5317-5322
12. Baums CG, Kock C, Beineke A, Bennecke K, Goethe R, Schroder C, Waldmann KH and Valentin-Weigand P. Streptococcus suis bacterin and subunit vaccine immunogenicities and protective efficacies against serotypes 2 and 9. Clinical and Vaccine Immunology,2009,16:200-208
13. Beier D, Gross R, Regulation of bacterial virulence by two-component systems. Current opinion in microbiology,2006,9:143-152
14. Benkirane R, Gottschalk M G, Dubreuil J D. Identification of a Streptococcus suis 60-KDa heat-shock protein using western blotting. Fems Microbiol Lett,1997, 153(2):379-385
15. Bina J, Zhu J, Dziejman M, et al. ToxR regulon of Vibrio cholerae and its expression in vibrios shed by cholera patients. Proceedings of the National Academy of Sciences of the United States of America 100,2003,2801-2806
16. Breton J, Mitchell W R, Rosendal S. Streptococcus suis in s laughter pigs and abattoir workers. Can J Vet Res,1986,50(3):338-341
17. B, Pedersen K B, Henrichsen J. Serology of capsulated streptococci pathogenic for pig six new serotypes of Streptococcus suis. J Clin Microbiol,1983,17(6):993-996.
18. Busque P, Higgins R, Caya F, Quessy S. Immunisation of pigs against Streptococcus suis serotype 2 infection using a live avirulent strain. Can J Vet Res, 1997,61:275-279.
19. Cegelski L, Marshall G R, Eldridge G R, Hultgren S J. The biology and future prospects of antivirulence therapies. Nature reviews,2008,6:17-27
20. Clifton Hadley FA, Alexander TJ, Enright MR, Guise J. Monitoring herds for Streptococcus suis type 2 by sampling tonsils of slaughter pigs. Vet Rec,1984,115: 562-564
21. Charland N, Harel J, Kobisch M, el al. Streptococcus suis serotype 2 mutants deficient in capsular expression. Microbiol,1998,144(2):325-332
22. Charland N, Nizet V, Rubens C E, et al. Streptococcus suis serotype 2 interactions with human brain microvascular endothelial cells. Infect Immun,2000,68(2): 637-643
23. Charland N, Nizet V, Rubens CE, Kim KS, Lacouture S and Gottschalk M. Streptococcus suis serotype 2 interactions with human brain microvascular endothelial cells.Infection and Immunity,2000,68:637-643
24. Clifton-hadleyfa.alex and ertjl.enright mr.thee pidemiology.diagnosis.tr Eatment And Control of Streptococcus suis Type 2. Infectionin Proe Am Assoc Swine Pract, 1986, P4.
25. Clifton-Hadley F A, Enrigllt M R, Alexander T J L. Survival of Streptococcus suis type 2 in pig carcases. Vet Rec,1986,118(10):275
26. Courtney HS, Hasty DL, Li Y, Chiang HC, Thacker JL and Dale JB. Serum opacity factor is a major fibronectin-binding protein and a virulence determinant of M type 2 Streptococcus pyogenes. Molecular Microbiology,1999,32:89-98
27. Dee S, A carlson A, Rwinkel manN.L et al. Effect of Management Practices On The Streptococcus suis Carries Rate In Nursery Swine. Am Vet Med Assoc,1993,2
28. de Greeff A, Buys H, Verhaar R, Dijkstra J, van Alphen L and Smith HE. Contribution of fibronectin-binding protein to pathogenesis of Streptococcus suis serotype 2. Infection and Immunity,2002,70:1319-1325
29. Devriese L. Aceyssens.K honunez..J et al. Characteristics of Different Streptococcus suis Ecovars And Deseription of A Simplified Identification Method. Vet Microbiol,1991,26.1
30. Enright M, R alexander T, clifton-hadley F A. Role of House flies(musca Domestica) InThe Epidemiology of Streptococcus suis Type2, Vet Rec.1987,1
31. Esgleas, Miriam Dominguez-Punaro, Maria de la et al. Immunization with SsEno fails to protect mice against challenge with Streptococcus suis serotype2. FEMS microbiology letters,2009,294(1):82-88
32. Feder I, Chengappa M M, Fenwick B, Rider M, Staats J. Partial characterization of Streptococcus suis type 2 hemolysin. J Clin Microbiol.1994,32(5):1256-1260
33. Ferrer N, Gomez A, Soto C et al. Intracellular replication of attenuated Mycobacterium tuberculosis phoP mutant in the absence of host cell cytotoxicity. Microbes and infection/Institut Pasteur,2009,11:115-122
34. Fontaine M C, Perez-Casal J, Willson P J. Investigation of a novel DNase of Streptococcus suis serotype 2. Infect Immun,2004,72(2):774-781
35. Francis C W. Bryant R G, Brenner B. et al. Magnetic resonance imaging of blood and clots in vitro. Invest Radiol,1990,25(12):1316-1324
36. Galilla L, Collins J E, Pijoin C. Porcine Streptococcus suis in Minnesota[J]. J Vet Diagn Invest,1992,4(2):195-196
37. Gogolewski R P, Cook R W. Streptococcus suis serotypes associated with disease in weaned pigs. Aust Vet J,1990,67(6):202-204
38. Gottschalk M, Higgins R, Beaudoin M. Quebec. Distribution of Streptococcus suis capsular types 9 to 22 according to the site of isolation. Can Vet J,1990,31(5):393
39. Gottschalk M G, Lacouture S, Dubreuil J D. Characterization of Streptococcus suis capsular type 2 haemolysin. Microbiology,1995,141 (Pt 1):189-195
40. Gottschalk M, Segura M and Xu J. Streptococcus suis infections in humans:the Chinese experience and the situation in North America. Animal Health Research Reviews,2007,8:29-45
41. Haataja S, Tikkanen K, Hytonen J, el al. The Gal alpha 1-4 Gal-binding adhesin of Streptococcus suis, a gram-positive meningitis-associated bacterium. Adv ExP Med Biol,1996,408:25-34
42. Higgins R,Gottschalk M, Boudreau M, et al. Description of six new capsular types of Streptococcus suis. J Vet Diagn Invest,1995,7:405-406
43. Hogg A, amass S F, hoffman L J et al. Survey of Streptococcus suis Serotype And Tissue of origin in Proc. Am Assoc Swine Prae,1996, P7
44. Homer C J. Asthma disease management. N Engl J Med,1997,337(20):1461-1463
45. Hung, D L, T L Raivio, C H Jones et al. Cpx signaling pathway monitors biogenesis and affects assembly and expression of P pili. EMBO J,2001,20: 1508-1518
46. Jacobs A, Loeffen P L, Van Den Berg A J, Storm P K. Identification, purification, and characterization of a thiol-activated hemolysin (suilysin) of Streptococcus suis. Infect Immun,1994,62(5):1742-1748
47. Jacques M, Gottschalk M, Foiry B, Higgins R. ultrastructural study of surface components of Streptococcus suis. J Bacteriol,1990,172(6):2833-2838
48. Jacobs AAC, Loeffen PLW, vandenBerg AJG and Storm PK. Identification, purification, and characterization of a thiol-activated hemolysin (suilysin) of Streptococcus suis. Infection and Immunity.1994,62:1742-1748
49. Jesu's Gonzalo-Asensio, Serge Mostowy et al., PhoP:A Missing Piece in the Intricate Puzzle of Mycobacterium tuberculosis Virulence. PloS one, 2008(3)10:1-11
50. Joanna Krzeslak, Gijs Gerritse, Ronald van Merkerk, Robbert H Cool, Wim J Quax. Lipase Expression in Pseudomonas alcaligenes Is Under the Control of a Two-Component Regulatory System. APPLIED AND ENVIRONMENTAL MICROBIOLOGY,2008,74(5):1402-1411
51. Jobin M C, Grenier D. Identification and characterization of four proteases produced by Streptococcus suis. Fems Microbiol Lett,2003,220(1):113-119
52. Jobin M C, Martinez G, Motard J, Gottschalk M, Grenier D. Cloning, purification, and enzymatic properties of dipeptidyl peptidase Ⅳ from the swine pathogen Streptococcus suis. J Bacteriol,2005,187(2):795-799
53. Kaneyoshi YAMAMOTO, Fumika MATSUMOTO, Shu MINAGAWA et al. Characterization of CitA-CitB Signal Transduction Genes Involved in Anaerobic Citrate Catabolism in Escherichia coli. Biosci Biotechnol Biochem,2009, 73(2):340-350
54. KataokaY, YoshidaT, SawadaT. A10-year survey of antimierobial suseeptibility of Streptococcus suis isolates from swine in Japan. JVet Med Sei,2000,62:1053-1059
55. King SJ, Allen AG, Maskell DJ, Dowson CG and Whatmore AM Distribution, genetic diversity, and variable expression of the gene encoding hyaluronate lyase within the Streptococcus suis population. Journal of Bacteriology.2004, 186:4740-4747
56. Kloosterman T G, Hendriksen W T, Bijlsma J J, Bootsma H J, Van Hijum S A, Kok J, Hermans P W, Kuipers O P. Regulation of glutamine and glutamate metabolism by GlnR and GlnA in Streptococcus pneumoniae. J Biol Chem.2006, 281(35):25097-25109
57. Labandeira-Rey, M, Mock, J.R, Hansen, E.J. Regulation of expression of the Haemophilus ducreyi LspB and LspA2 proteins by CpxR. Infection and immunity, 2009,77:3402-3411
58. Lalonde M, Segura M, Lacouture S, Gottschalk M. Interactions between Streptococcus suis serotype 2 and different epithelial cell lines. Microbiology+, 2000,146 (Pt 8):1913-1921
59. Laurentiu Benga, Doris Hoeltig, Thomas Rehm et al. Expression levels of immune markers in Actinobacillus pleuropneumoniae infected pigs and their relation to breed and clinical symptoms. BMC Veterinary Research,2009,5(13):1-12
60. Liu M, Hanks T, Zhang J et al. Defects in ex vivo and in vivo growth and sensitivity to osmotic stress of group A Streptococcus caused by interruption of response regulator gene vicR. Microbiology (England),2006,152:967-978
61. Lukat G, Mc Cleary, W R, Stock A, M Stock J. Phosphorylation of bacterial response regulator proteins by low molecular weight phospho-donors. Proc Natl Acad Sci,1992,89,718-722
62. Lun S, Perez-Casal J, Connor W, Willson P J. Role of suilysin in pathogenesis of Streptococcus suis capsular serotype 2. Microb Pathog,2003,34(1):27-37
63. Lun ZR, Wang QP, Chen XG, Li AX and Zhu XQ. Streptococcus suis:an emerging zoonotic pathogen. Lancet Infectious Diseases,2007,7:201-209
64. McCluskey J, Hinds J, Husain S et al. A two-component system that controls the expression of pneumococcal surface antigen A (PsaA) and regulates virulence and resistance to oxidative stress in Streptococcus pneumoniae. Molecular microbiology, 2004,51:1661-1675
65. Melanie Brocker, Steffen Schaffer, Christina Mack, and Michael Bott. Citrate Utilization by Corynebacterium glutamicum is Controlled by the CitAB Two-Component System through Positive Regulation of the Citrate Transport Genes citH and tctCBA. JOURNAL OF BACTERIOLOGY.2009, 191(12):3869-3880
66. Ming Li, Changjun Wang, Youjun Feng, Xiuzhen Pan, Gong Cheng, Jing Ge, Feng Zheng, Fuquan Hu, Jiaqi Tang. SalK/SalR, a Two-Component Signal Transduction System, Is Essential for Full Virulence of Highly Invasive Streptococcus Suis Serotype 2. PLoS ONE,2008,3(5):e2080
67. M S Princivalli, C Palmieri, G Magi, C Vignaroli, A Manzin, A Camporese, S Barocci, C Magistrali, B Facinelli. Genetic diversity of streptococcus suis clinical isolates from piGs and humans in italy(2003-2007). EUROSURVEILLANCE,2009, 14(33):1-7
68. Nahuel F, Tsutomu S, Daisuke T et al. Significant contribution of the pgdA gene to the virulence of Streptococcus suis. Molecular Microbiology,2008,70(5): 1120-1135
69. Norton P M, Leigh J A. Virulence mechanisms of Streptococcus suis. Adv Exp Med Biol.1997,418:823-825
70. Norton P M, Rolph C, Ward PN et al. Epithelial Invasion and cell lysis by virulent strains of Streptococcus suis is enhanced by the presence of suilysin. FEMS Immunol Med Microbiol,1999,26(1):25-35
71. Ojha S, Lacouture S, Gottschalk M, Maclnnes J I. Characterization of colonization-deficient mutants of Actinobacillus suis. Veterinary microbiology, 2004,140:122-130
72. Qiaoyun Hu, Peng Liu, Zhengjun Yu et al. Identification of a cell wall-associated subtilisin-like serine protease involved in the pathogenesis of Streptococcus suis serotype 2. Microbial Pathogenesis,2009,1-7
73. Pan X, Ge J, Li M et al. The orphan response regulator CovR:a globally negative modulator of virulence in Streptococcus suis serotype 2. Journal of bacteriology, 2009,191:2601-2612
74. Perch Oggioni M, Iannelli F, Ricci S et al. Antibacterial activity of a competence-stimulating peptide in experimental sepsis caused by Streptococcus pneumoniae. Antimicrobial agents and chemotherapy,48:4725-4732.
75. Quessy S, Busque P, Higgins R, Jacques M, Dubreuil J D. Description of an albumin binding activity for Streptococcus suis serotype 2. Fems Microbiol Lett, 1997,147(2):245-250
76. Rasko D A, Moreira C G, Li de R et al. Targeting QseC signaling and virulence for antibiotic development. Science,2008,321:1078-1080
77. Ream R Y, Glickman L T, Harrington D D et al. Streptococcus suis infection in swine:a retrospective study of 256 cases. Part 2. Clinical signs, gross and microscopic lesions, and coexisting microorganisms. J Vet Diagn Invest,1994, 6(3):326-334
78. Robertson ID, Blackmore DK. Prevalence of Streptococcus suis types 1 and 2 in domestic pigs in Australia and New Zealand. Vet Rec,1989,124:391-394.
79. Roberton. D,blacklnore D,K hampson D et al. A Longitudinal Study of Natural Infection of Piglets With Streptococcus suis Types 1 and 2. Epideminol Infect,1991, 1
80. Tyler K Nygaard, Kyler B Pallister, Peter Ruzevich et al. SaeR Binds a Consensus Sequence within Virulence Gene Promoters to Advance USA300 Pathogenesis. Infectious Diseases Society of America,2010,201:241-254
81. Sala V colombo A And Gerola L. InfectionRisks of Streptococcus suis Type 2 Loealizations in Slaughtered Swine. Arch Vet Italiano,1989,40:1
82. Sarah S, Michael B. Target Genes and DNA-Binding Sites of the Response Regulator PhoR from Corynebacterium glutamicum. Journal of Bacteriology,2007, 189(14):5002-5011
83. Seddon S V, Hemingway I, Borriello S P. Hydrolytic enzyme production by Clostridium difficile and its relationship to toxin production and virulence in the hamster model. JMed Microbiol,1990,31(3):169-174
84. Segura M A, Cleroux P, Gottschalk M. Streptococcus suis and group B Streptococcus differ in their interactions with murine macrophages. FEMS Immunol Med Microbiol.1998,21(3):189-195
85. Segers RPAM, Kenter T, de Haan LAM and Jacobs AAC. Characterisation of the gene encoding suilysin from Streptococcus suis and expression in field strains. FEMS Microbiology Letters.1998,167:255-261
86. Segura M, Stankova J, Gottsehalk M. Heat-killed Streptococcus suis Capsular Type2 Stiains Stimulate Tumor Neerosis Factor AIPha and Interieukin-6 Produetion by Murine MacroPhages. Infect Immun,1999,67:4646-4654
87. Segura M, Vadeboncoeur N, Gottschalk M. CD14-dependent and-independent cytokine and chemokine production by human THP-1 monocytes stimulated by Streptococcus suis capsular type 2. Clin Exp Immunol.2002,127(2):243-254
88. Segura M A, Cleroux P, Gottsehalk M. Streptococcus suis and group B Streptococcus differ in their interactions with murine, macrophages. FEMS Immunol Med Microbiol,1998,21(3):189-195
89. Segura M, Vadeboncoeur N, Gottschalk M. CD14-dependent and independent cytokine and chemokine production by human THP-1 monocytes stimulated by Streptococcus suis capsular type 2. Clin Exp Immunol,2002,127(2):243-254
90. Smith H E, Buijs H, Wisselink H J, Stockhofe-Zurwieden N, Smits M A. Selection of virulence-associated determinants of Streptococcus suis serotype 2 by in vivo complementation. Infect Immun,2001,69(3):1961-1966
91. Smith H E, Reek F H, Vecht U, Gielkens A L, Smits M A. Repeats in an extracellular protein of weakly pathogenic strains of Streptococcus suis type 2 are absent in pathogenic strains. Infect Immun,1993,61(8):3318-3326
92. Smith H E, Vecht U, Wisselink H J, Stockhofe-Zurwieden N, Biermann Y, Smits M A. Mutants of Streptococcus suis types 1 and 2 impaired in expression of muramidase-released protein and extracellular protein induce disease in newborn germfree pigs. Infect Immun,1996,64(10):4409-4412
93. Smitll H E, Veenbergen V, Velde J, el al. The cps genes of Streptococcus suis serotypes 1,2 and 9:development of rapid serotype-specific PCR assays. J Clin Microbiol,1999,37(10):3146-3152
94. Smith HE, Buijs H, de Vries RR, Wisselink HJ, Stockhofe Zurwieden N and Smits MA. Environmentally regulated genes of Streptococcus suis:identification by the use of iron-restricted conditions in vitro and by experimental infection of piglets. Microbiology,2001,147:271-280
95. Staats J J, Feder 1, Okwumabua O et al. Streptococcus suis:Past and present. Vet Res Common,1997,21(6):38-407
96. Staats JJ, Feder I, Okwumabua O, Chengappa MM. Streptococcus suis:past and present. Vet Res Commun,1997,21:381-407.
97. Staats J J, Plattner B L, Nietfeld J, Dritz S, Chengappa M M. Use of ribotyping and hemolysin activity to identify highly virulent Streptococcus suis type 2 isolates. J Clin Microbiol,1998,36(1):15-19
98. Staats JJ, Plattner BL, Stewart GC and Chengappa MM. Presence of the Streptococcus suis suilysin gene and expression of MRP and EF correlates with high virulence in Streptococcus suis type 2 isolates. Veterinary Microbiology.1999, 70:201-211
99. Takamatsu D, Osaki M and Sekizaki T. Evidence for lateral transfer of the suilysin gene region of Streptococcus suis. Journal of Bacteriology.2002,184:2050-2057
100.Tang, J et al. Streptococcal toxic shock syndrome caused by Streptococcus suis serotype 2. PLoS Med,2006.3(5):151.
101.Tao wu, Weicheng Bei, Huanchun Chen et al. The Orphan Response Regulator RevSC21 Controls the Attachment of Streptococcus Suis serotype-2 to Human Laryngeal Epithelial Cells and the Expression of Virulence Genes. FEMS Microbiology Letter,2009,292(2):170-181
102.Tarradas C, Luque I, Andres D D et al. Epidemiological relationship of human and swine Streptococcus suis isolates. Vet Med B,2001,48(5):347-355
103.Touil F, HigginsR, NadeauM. Isolation of Streptococcus suis from diseased pigs inCanada. Vet Mierobiol,1988,17:171-177
104.Throup J P, Koretke K K, Bryant A et al. A genomie analysis of two-component signal transduction in Streptococcus pneumoniae. Mol Microbiol,2000,35(3): 566-576
105.Tuomanen E. Entry of pathogens into the central nervous system. FEMS Mierobiol Rev,18(4):289-299
106.Vadeboneoeur N, Segura M, AI-Numani D. Pro-inflanunatory cytokine and Chemokine release by human brain microvascular endothelial cells stimulated by Streptococcus suis serotype 2. FEMS Immunol Med Mierobiol,2003,35(1): 549-581
107.Vanier G, Segura M, Fried P, Lacouture S, Gottsehalk M. Invasion of porcine Brain Mierovascular Endothelial Cells by Streptococcus suis Serotype 2. Infect Inunun, 2004,72:1441-1449
108.Vecht U, Wisselink H J, Jellema M L et al. Identification of two proteins associated with virulence of Streptococcus suis type 2. Infect Immun,1991,59(9):3156-3162
109.Verhamme D T, Arents J C, Postma P W, Crielaard W, Hellingwerf K J. Investigation of in vivo cross-talk between key two-component systems of Escherichia coli. Microbiology,2002,148:69-78
110.Windsor R S and Elliott S D. Streptococcal infection in yong pigs,Ⅳ.An outbreak of streptococcal meningitis in weaned pigs. J Hyg(Lond),1975,75(1):69-78
111.Williams A, Blakemore W F. Pathogenesis of meningitis caused by Streptococcus suis type 2. J Infect Dis,1990,162(2):474-481
112.Windsor R S. Meningitis in pigs caused by Streptococcus suis type Ⅱ. Vet Rec, 1977,101(19):378-379
113.Wisselink HJ, Vecht U, Stockhofe-Zurwieden N and Smith HE. Protection of pigs against challenge with virulent Streptococcus suis serotype 2 strains by a muramidase released protein and extracellular factor vaccine. The Veterinary Record,2001,148:473-477
114.Wu T, Chang H, Tan C, Bei W, Chen H. The orphan response regulator RevSC21 controls the attachment of Streptococcus suis serotype 2 to human laryngeal epithelial cells and the expression of virulence genes. Fems Microbiol Lett.2009, 292(2):170-181
115.Xiangan Han, Chengping Lu. Biological activity and identication of apeptide inhibitor of Lux From Streptococcus suis serotype 2. FEMS Microbiol Lett,2009, 294:16-23
116.Yih-Ling Tzeng, Charlene M K, Xinjian Zhang, David S S. MisR/MisS Two-Component Regulon in Neisseria meningitides.2008,76(2):704-716
117.Ying Ma, Youjun Feng, Di Liu, George F Gao. Serotype 2, severe Streptococcus suis Avian influenza virus, acute respiratory syndrome-coronavirus and beyond: molecular epidemiology, ecology and the situation in China. Phil Trans R Soc B, 2009 364,2725-2737
118.Y Wang, J H Sun, C P Lu. Purified Recombinant Phage Lysin LySMP:An Extensive Spectrum of Lytic Activity for Swine Streptococci. Curr Microbiol,2009, 58:609-615
119.Yuanyi Li, Marcelo G, Miriam E et al. Immunization with Recombinant Sao Protein Confers Protection against Streptococcus suis Infection. CLINICAL AND VACCINE IMMUNOLOGY,2007,14(8):937-943
120.Yu H J, Liu X C, Wang S W, Liu L G, Zu R Q, Zhong W J, Zhu X P, Xiang N J, Yuan H, Meng L, Ou Y B, Gao Y J, Lv Q, Huang Y, An X D, Huang T, Zhou X Y, Feng L, Pang Q D, Yang W Z. [Matched case-control study for risk factors of human Streptococcus suis infection in Sichuan Province, China. Zhonghua Liu Xing Bing Xue Za Zhi.2005,26(9):636-639
121.Yu H, Jing H, Chen Z, Zheng H, Zhu X, Wang H, Wang S, Liu L, Zu R, Luo L, Xiang N, Liu H, Liu X, Shu Y, Lee S S, Chuang S K, Wang Y, Xu J, Yang W. Human Streptococcus suis outbreak, Sichuan, China. Emerg Infect Dis.2006,12(6): 914-920
2.胡丹.SS2荚膜缺失株的构建及其致病性研究.[博士学位论文].武汉：华中农业大学图书馆,2009
3.李明.信号转导系统SalK/SalR调控高致病性2型猪链球菌毒力的实验研究.[博士学位论文].武汉：华中农业大学图书馆,2008
4.娄素.恶臭假单胞菌CD2中双组分系统ColR-ColS调控机制的初步研究.[硕士学位论文].武汉：华中农业大学图书馆,2008
5.齐.猪链球菌2型毒力相关基因的研究.[博士学位论文].武汉：华中农业大学图书馆,2008
6. 黄友谊.结核分枝杆菌螺旋酶与DNA的相互作用研究.[博士学位论文].武汉：华中农业大学图书馆,2006
7.司有辉.谷氨酰胺合成酶GlnA及其转录调节因子GlnR对2型猪链球菌致病力影响的研究.[博士学位论文].武汉：华中农业大学图书馆,2009
8. 曾小涛,袁媛,郑玉玲,周冬生,姜永强,陈福生.SS2全基因组DNA芯片的研制及基因表达谱技术平台的建立.生物技术通讯.2009,20(5)：658-661
9. Anding Zhang, Bo Chen, Xiaofeng Mu, Yaxin Zhao, Pei Zheng, Huanchun Chen, Meilin Jin. Identication of three novel in vivo-induced expressed antigens during infection with Streptococcus suis serotype 2. FEMS Microbiol Lett 2009,295: 17-22
10. Allen A G, Lindsay H, Seilly D, Bolitho S, Peters S E, Maskell D J. Identification and characterisation of hyaluronate lyase from Streptococcus suis. Microb Pathog, 2004,36(6):327-335
11. Barrett J F, Goldschmidt R M, Lawrence L E, et al, Antibacterial agents that inhibit two-component signal transduction systems. PNAS,1998,95:5317-5322
12. Baums CG, Kock C, Beineke A, Bennecke K, Goethe R, Schroder C, Waldmann KH and Valentin-Weigand P. Streptococcus suis bacterin and subunit vaccine immunogenicities and protective efficacies against serotypes 2 and 9. Clinical and Vaccine Immunology,2009,16:200-208
13. Beier D, Gross R, Regulation of bacterial virulence by two-component systems. Current opinion in microbiology,2006,9:143-152
14. Benkirane R, Gottschalk M G, Dubreuil J D. Identification of a Streptococcus suis 60-KDa heat-shock protein using western blotting. Fems Microbiol Lett,1997, 153(2):379-385
15. Bina J, Zhu J, Dziejman M, et al. ToxR regulon of Vibrio cholerae and its expression in vibrios shed by cholera patients. Proceedings of the National Academy of Sciences of the United States of America 100,2003,2801-2806
16. Breton J, Mitchell W R, Rosendal S. Streptococcus suis in s laughter pigs and abattoir workers. Can J Vet Res,1986,50(3):338-341
17. B, Pedersen K B, Henrichsen J. Serology of capsulated streptococci pathogenic for pig six new serotypes of Streptococcus suis. J Clin Microbiol,1983,17(6):993-996.
18. Busque P, Higgins R, Caya F, Quessy S. Immunisation of pigs against Streptococcus suis serotype 2 infection using a live avirulent strain. Can J Vet Res, 1997,61:275-279.
19. Cegelski L, Marshall G R, Eldridge G R, Hultgren S J. The biology and future prospects of antivirulence therapies. Nature reviews,2008,6:17-27
20. Clifton Hadley FA, Alexander TJ, Enright MR, Guise J. Monitoring herds for Streptococcus suis type 2 by sampling tonsils of slaughter pigs. Vet Rec,1984,115: 562-564
21. Charland N, Harel J, Kobisch M, el al. Streptococcus suis serotype 2 mutants deficient in capsular expression. Microbiol,1998,144(2):325-332
22. Charland N, Nizet V, Rubens C E, et al. Streptococcus suis serotype 2 interactions with human brain microvascular endothelial cells. Infect Immun,2000,68(2): 637-643
23. Charland N, Nizet V, Rubens CE, Kim KS, Lacouture S and Gottschalk M. Streptococcus suis serotype 2 interactions with human brain microvascular endothelial cells.Infection and Immunity,2000,68:637-643
24. Clifton-hadleyfa.alex and ertjl.enright mr.thee pidemiology.diagnosis.tr Eatment And Control of Streptococcus suis Type 2. Infectionin Proe Am Assoc Swine Pract, 1986, P4.
25. Clifton-Hadley F A, Enrigllt M R, Alexander T J L. Survival of Streptococcus suis type 2 in pig carcases. Vet Rec,1986,118(10):275
26. Courtney HS, Hasty DL, Li Y, Chiang HC, Thacker JL and Dale JB. Serum opacity factor is a major fibronectin-binding protein and a virulence determinant of M type 2 Streptococcus pyogenes. Molecular Microbiology,1999,32:89-98
27. Dee S, A carlson A, Rwinkel manN.L et al. Effect of Management Practices On The Streptococcus suis Carries Rate In Nursery Swine. Am Vet Med Assoc,1993,2
28. de Greeff A, Buys H, Verhaar R, Dijkstra J, van Alphen L and Smith HE. Contribution of fibronectin-binding protein to pathogenesis of Streptococcus suis serotype 2. Infection and Immunity,2002,70:1319-1325
29. Devriese L. Aceyssens.K honunez..J et al. Characteristics of Different Streptococcus suis Ecovars And Deseription of A Simplified Identification Method. Vet Microbiol,1991,26.1
30. Enright M, R alexander T, clifton-hadley F A. Role of House flies(musca Domestica) InThe Epidemiology of Streptococcus suis Type2, Vet Rec.1987,1
31. Esgleas, Miriam Dominguez-Punaro, Maria de la et al. Immunization with SsEno fails to protect mice against challenge with Streptococcus suis serotype2. FEMS microbiology letters,2009,294(1):82-88
32. Feder I, Chengappa M M, Fenwick B, Rider M, Staats J. Partial characterization of Streptococcus suis type 2 hemolysin. J Clin Microbiol.1994,32(5):1256-1260
33. Ferrer N, Gomez A, Soto C et al. Intracellular replication of attenuated Mycobacterium tuberculosis phoP mutant in the absence of host cell cytotoxicity. Microbes and infection/Institut Pasteur,2009,11:115-122
34. Fontaine M C, Perez-Casal J, Willson P J. Investigation of a novel DNase of Streptococcus suis serotype 2. Infect Immun,2004,72(2):774-781
35. Francis C W. Bryant R G, Brenner B. et al. Magnetic resonance imaging of blood and clots in vitro. Invest Radiol,1990,25(12):1316-1324
36. Galilla L, Collins J E, Pijoin C. Porcine Streptococcus suis in Minnesota[J]. J Vet Diagn Invest,1992,4(2):195-196
37. Gogolewski R P, Cook R W. Streptococcus suis serotypes associated with disease in weaned pigs. Aust Vet J,1990,67(6):202-204
38. Gottschalk M, Higgins R, Beaudoin M. Quebec. Distribution of Streptococcus suis capsular types 9 to 22 according to the site of isolation. Can Vet J,1990,31(5):393
39. Gottschalk M G, Lacouture S, Dubreuil J D. Characterization of Streptococcus suis capsular type 2 haemolysin. Microbiology,1995,141 (Pt 1):189-195
40. Gottschalk M, Segura M and Xu J. Streptococcus suis infections in humans:the Chinese experience and the situation in North America. Animal Health Research Reviews,2007,8:29-45
41. Haataja S, Tikkanen K, Hytonen J, el al. The Gal alpha 1-4 Gal-binding adhesin of Streptococcus suis, a gram-positive meningitis-associated bacterium. Adv ExP Med Biol,1996,408:25-34
42. Higgins R,Gottschalk M, Boudreau M, et al. Description of six new capsular types of Streptococcus suis. J Vet Diagn Invest,1995,7:405-406
43. Hogg A, amass S F, hoffman L J et al. Survey of Streptococcus suis Serotype And Tissue of origin in Proc. Am Assoc Swine Prae,1996, P7
44. Homer C J. Asthma disease management. N Engl J Med,1997,337(20):1461-1463
45. Hung, D L, T L Raivio, C H Jones et al. Cpx signaling pathway monitors biogenesis and affects assembly and expression of P pili. EMBO J,2001,20: 1508-1518
46. Jacobs A, Loeffen P L, Van Den Berg A J, Storm P K. Identification, purification, and characterization of a thiol-activated hemolysin (suilysin) of Streptococcus suis. Infect Immun,1994,62(5):1742-1748
47. Jacques M, Gottschalk M, Foiry B, Higgins R. ultrastructural study of surface components of Streptococcus suis. J Bacteriol,1990,172(6):2833-2838
48. Jacobs AAC, Loeffen PLW, vandenBerg AJG and Storm PK. Identification, purification, and characterization of a thiol-activated hemolysin (suilysin) of Streptococcus suis. Infection and Immunity.1994,62:1742-1748
49. Jesu's Gonzalo-Asensio, Serge Mostowy et al., PhoP:A Missing Piece in the Intricate Puzzle of Mycobacterium tuberculosis Virulence. PloS one, 2008(3)10:1-11
50. Joanna Krzeslak, Gijs Gerritse, Ronald van Merkerk, Robbert H Cool, Wim J Quax. Lipase Expression in Pseudomonas alcaligenes Is Under the Control of a Two-Component Regulatory System. APPLIED AND ENVIRONMENTAL MICROBIOLOGY,2008,74(5):1402-1411
51. Jobin M C, Grenier D. Identification and characterization of four proteases produced by Streptococcus suis. Fems Microbiol Lett,2003,220(1):113-119
52. Jobin M C, Martinez G, Motard J, Gottschalk M, Grenier D. Cloning, purification, and enzymatic properties of dipeptidyl peptidase Ⅳ from the swine pathogen Streptococcus suis. J Bacteriol,2005,187(2):795-799
53. Kaneyoshi YAMAMOTO, Fumika MATSUMOTO, Shu MINAGAWA et al. Characterization of CitA-CitB Signal Transduction Genes Involved in Anaerobic Citrate Catabolism in Escherichia coli. Biosci Biotechnol Biochem,2009, 73(2):340-350
54. KataokaY, YoshidaT, SawadaT. A10-year survey of antimierobial suseeptibility of Streptococcus suis isolates from swine in Japan. JVet Med Sei,2000,62:1053-1059
55. King SJ, Allen AG, Maskell DJ, Dowson CG and Whatmore AM Distribution, genetic diversity, and variable expression of the gene encoding hyaluronate lyase within the Streptococcus suis population. Journal of Bacteriology.2004, 186:4740-4747
56. Kloosterman T G, Hendriksen W T, Bijlsma J J, Bootsma H J, Van Hijum S A, Kok J, Hermans P W, Kuipers O P. Regulation of glutamine and glutamate metabolism by GlnR and GlnA in Streptococcus pneumoniae. J Biol Chem.2006, 281(35):25097-25109
57. Labandeira-Rey, M, Mock, J.R, Hansen, E.J. Regulation of expression of the Haemophilus ducreyi LspB and LspA2 proteins by CpxR. Infection and immunity, 2009,77:3402-3411
58. Lalonde M, Segura M, Lacouture S, Gottschalk M. Interactions between Streptococcus suis serotype 2 and different epithelial cell lines. Microbiology+, 2000,146 (Pt 8):1913-1921
59. Laurentiu Benga, Doris Hoeltig, Thomas Rehm et al. Expression levels of immune markers in Actinobacillus pleuropneumoniae infected pigs and their relation to breed and clinical symptoms. BMC Veterinary Research,2009,5(13):1-12
60. Liu M, Hanks T, Zhang J et al. Defects in ex vivo and in vivo growth and sensitivity to osmotic stress of group A Streptococcus caused by interruption of response regulator gene vicR. Microbiology (England),2006,152:967-978
61. Lukat G, Mc Cleary, W R, Stock A, M Stock J. Phosphorylation of bacterial response regulator proteins by low molecular weight phospho-donors. Proc Natl Acad Sci,1992,89,718-722
62. Lun S, Perez-Casal J, Connor W, Willson P J. Role of suilysin in pathogenesis of Streptococcus suis capsular serotype 2. Microb Pathog,2003,34(1):27-37
63. Lun ZR, Wang QP, Chen XG, Li AX and Zhu XQ. Streptococcus suis:an emerging zoonotic pathogen. Lancet Infectious Diseases,2007,7:201-209
64. McCluskey J, Hinds J, Husain S et al. A two-component system that controls the expression of pneumococcal surface antigen A (PsaA) and regulates virulence and resistance to oxidative stress in Streptococcus pneumoniae. Molecular microbiology, 2004,51:1661-1675
65. Melanie Brocker, Steffen Schaffer, Christina Mack, and Michael Bott. Citrate Utilization by Corynebacterium glutamicum is Controlled by the CitAB Two-Component System through Positive Regulation of the Citrate Transport Genes citH and tctCBA. JOURNAL OF BACTERIOLOGY.2009, 191(12):3869-3880
66. Ming Li, Changjun Wang, Youjun Feng, Xiuzhen Pan, Gong Cheng, Jing Ge, Feng Zheng, Fuquan Hu, Jiaqi Tang. SalK/SalR, a Two-Component Signal Transduction System, Is Essential for Full Virulence of Highly Invasive Streptococcus Suis Serotype 2. PLoS ONE,2008,3(5):e2080
67. M S Princivalli, C Palmieri, G Magi, C Vignaroli, A Manzin, A Camporese, S Barocci, C Magistrali, B Facinelli. Genetic diversity of streptococcus suis clinical isolates from piGs and humans in italy(2003-2007). EUROSURVEILLANCE,2009, 14(33):1-7
68. Nahuel F, Tsutomu S, Daisuke T et al. Significant contribution of the pgdA gene to the virulence of Streptococcus suis. Molecular Microbiology,2008,70(5): 1120-1135
69. Norton P M, Leigh J A. Virulence mechanisms of Streptococcus suis. Adv Exp Med Biol.1997,418:823-825
70. Norton P M, Rolph C, Ward PN et al. Epithelial Invasion and cell lysis by virulent strains of Streptococcus suis is enhanced by the presence of suilysin. FEMS Immunol Med Microbiol,1999,26(1):25-35
71. Ojha S, Lacouture S, Gottschalk M, Maclnnes J I. Characterization of colonization-deficient mutants of Actinobacillus suis. Veterinary microbiology, 2004,140:122-130
72. Qiaoyun Hu, Peng Liu, Zhengjun Yu et al. Identification of a cell wall-associated subtilisin-like serine protease involved in the pathogenesis of Streptococcus suis serotype 2. Microbial Pathogenesis,2009,1-7
73. Pan X, Ge J, Li M et al. The orphan response regulator CovR:a globally negative modulator of virulence in Streptococcus suis serotype 2. Journal of bacteriology, 2009,191:2601-2612
74. Perch Oggioni M, Iannelli F, Ricci S et al. Antibacterial activity of a competence-stimulating peptide in experimental sepsis caused by Streptococcus pneumoniae. Antimicrobial agents and chemotherapy,48:4725-4732.
75. Quessy S, Busque P, Higgins R, Jacques M, Dubreuil J D. Description of an albumin binding activity for Streptococcus suis serotype 2. Fems Microbiol Lett, 1997,147(2):245-250
76. Rasko D A, Moreira C G, Li de R et al. Targeting QseC signaling and virulence for antibiotic development. Science,2008,321:1078-1080
77. Ream R Y, Glickman L T, Harrington D D et al. Streptococcus suis infection in swine:a retrospective study of 256 cases. Part 2. Clinical signs, gross and microscopic lesions, and coexisting microorganisms. J Vet Diagn Invest,1994, 6(3):326-334
78. Robertson ID, Blackmore DK. Prevalence of Streptococcus suis types 1 and 2 in domestic pigs in Australia and New Zealand. Vet Rec,1989,124:391-394.
79. Roberton. D,blacklnore D,K hampson D et al. A Longitudinal Study of Natural Infection of Piglets With Streptococcus suis Types 1 and 2. Epideminol Infect,1991, 1
80. Tyler K Nygaard, Kyler B Pallister, Peter Ruzevich et al. SaeR Binds a Consensus Sequence within Virulence Gene Promoters to Advance USA300 Pathogenesis. Infectious Diseases Society of America,2010,201:241-254
81. Sala V colombo A And Gerola L. InfectionRisks of Streptococcus suis Type 2 Loealizations in Slaughtered Swine. Arch Vet Italiano,1989,40:1
82. Sarah S, Michael B. Target Genes and DNA-Binding Sites of the Response Regulator PhoR from Corynebacterium glutamicum. Journal of Bacteriology,2007, 189(14):5002-5011
83. Seddon S V, Hemingway I, Borriello S P. Hydrolytic enzyme production by Clostridium difficile and its relationship to toxin production and virulence in the hamster model. JMed Microbiol,1990,31(3):169-174
84. Segura M A, Cleroux P, Gottschalk M. Streptococcus suis and group B Streptococcus differ in their interactions with murine macrophages. FEMS Immunol Med Microbiol.1998,21(3):189-195
85. Segers RPAM, Kenter T, de Haan LAM and Jacobs AAC. Characterisation of the gene encoding suilysin from Streptococcus suis and expression in field strains. FEMS Microbiology Letters.1998,167:255-261
86. Segura M, Stankova J, Gottsehalk M. Heat-killed Streptococcus suis Capsular Type2 Stiains Stimulate Tumor Neerosis Factor AIPha and Interieukin-6 Produetion by Murine MacroPhages. Infect Immun,1999,67:4646-4654
87. Segura M, Vadeboncoeur N, Gottschalk M. CD14-dependent and-independent cytokine and chemokine production by human THP-1 monocytes stimulated by Streptococcus suis capsular type 2. Clin Exp Immunol.2002,127(2):243-254
88. Segura M A, Cleroux P, Gottsehalk M. Streptococcus suis and group B Streptococcus differ in their interactions with murine, macrophages. FEMS Immunol Med Microbiol,1998,21(3):189-195
89. Segura M, Vadeboncoeur N, Gottschalk M. CD14-dependent and independent cytokine and chemokine production by human THP-1 monocytes stimulated by Streptococcus suis capsular type 2. Clin Exp Immunol,2002,127(2):243-254
90. Smith H E, Buijs H, Wisselink H J, Stockhofe-Zurwieden N, Smits M A. Selection of virulence-associated determinants of Streptococcus suis serotype 2 by in vivo complementation. Infect Immun,2001,69(3):1961-1966
91. Smith H E, Reek F H, Vecht U, Gielkens A L, Smits M A. Repeats in an extracellular protein of weakly pathogenic strains of Streptococcus suis type 2 are absent in pathogenic strains. Infect Immun,1993,61(8):3318-3326
92. Smith H E, Vecht U, Wisselink H J, Stockhofe-Zurwieden N, Biermann Y, Smits M A. Mutants of Streptococcus suis types 1 and 2 impaired in expression of muramidase-released protein and extracellular protein induce disease in newborn germfree pigs. Infect Immun,1996,64(10):4409-4412
93. Smitll H E, Veenbergen V, Velde J, el al. The cps genes of Streptococcus suis serotypes 1,2 and 9:development of rapid serotype-specific PCR assays. J Clin Microbiol,1999,37(10):3146-3152
94. Smith HE, Buijs H, de Vries RR, Wisselink HJ, Stockhofe Zurwieden N and Smits MA. Environmentally regulated genes of Streptococcus suis:identification by the use of iron-restricted conditions in vitro and by experimental infection of piglets. Microbiology,2001,147:271-280
95. Staats J J, Feder 1, Okwumabua O et al. Streptococcus suis:Past and present. Vet Res Common,1997,21(6):38-407
96. Staats JJ, Feder I, Okwumabua O, Chengappa MM. Streptococcus suis:past and present. Vet Res Commun,1997,21:381-407.
97. Staats J J, Plattner B L, Nietfeld J, Dritz S, Chengappa M M. Use of ribotyping and hemolysin activity to identify highly virulent Streptococcus suis type 2 isolates. J Clin Microbiol,1998,36(1):15-19
98. Staats JJ, Plattner BL, Stewart GC and Chengappa MM. Presence of the Streptococcus suis suilysin gene and expression of MRP and EF correlates with high virulence in Streptococcus suis type 2 isolates. Veterinary Microbiology.1999, 70:201-211
99. Takamatsu D, Osaki M and Sekizaki T. Evidence for lateral transfer of the suilysin gene region of Streptococcus suis. Journal of Bacteriology.2002,184:2050-2057
100.Tang, J et al. Streptococcal toxic shock syndrome caused by Streptococcus suis serotype 2. PLoS Med,2006.3(5):151.
101.Tao wu, Weicheng Bei, Huanchun Chen et al. The Orphan Response Regulator RevSC21 Controls the Attachment of Streptococcus Suis serotype-2 to Human Laryngeal Epithelial Cells and the Expression of Virulence Genes. FEMS Microbiology Letter,2009,292(2):170-181
102.Tarradas C, Luque I, Andres D D et al. Epidemiological relationship of human and swine Streptococcus suis isolates. Vet Med B,2001,48(5):347-355
103.Touil F, HigginsR, NadeauM. Isolation of Streptococcus suis from diseased pigs inCanada. Vet Mierobiol,1988,17:171-177
104.Throup J P, Koretke K K, Bryant A et al. A genomie analysis of two-component signal transduction in Streptococcus pneumoniae. Mol Microbiol,2000,35(3): 566-576
105.Tuomanen E. Entry of pathogens into the central nervous system. FEMS Mierobiol Rev,18(4):289-299
106.Vadeboneoeur N, Segura M, AI-Numani D. Pro-inflanunatory cytokine and Chemokine release by human brain microvascular endothelial cells stimulated by Streptococcus suis serotype 2. FEMS Immunol Med Mierobiol,2003,35(1): 549-581
107.Vanier G, Segura M, Fried P, Lacouture S, Gottsehalk M. Invasion of porcine Brain Mierovascular Endothelial Cells by Streptococcus suis Serotype 2. Infect Inunun, 2004,72:1441-1449
108.Vecht U, Wisselink H J, Jellema M L et al. Identification of two proteins associated with virulence of Streptococcus suis type 2. Infect Immun,1991,59(9):3156-3162
109.Verhamme D T, Arents J C, Postma P W, Crielaard W, Hellingwerf K J. Investigation of in vivo cross-talk between key two-component systems of Escherichia coli. Microbiology,2002,148:69-78
110.Windsor R S and Elliott S D. Streptococcal infection in yong pigs,Ⅳ.An outbreak of streptococcal meningitis in weaned pigs. J Hyg(Lond),1975,75(1):69-78
111.Williams A, Blakemore W F. Pathogenesis of meningitis caused by Streptococcus suis type 2. J Infect Dis,1990,162(2):474-481
112.Windsor R S. Meningitis in pigs caused by Streptococcus suis type Ⅱ. Vet Rec, 1977,101(19):378-379
113.Wisselink HJ, Vecht U, Stockhofe-Zurwieden N and Smith HE. Protection of pigs against challenge with virulent Streptococcus suis serotype 2 strains by a muramidase released protein and extracellular factor vaccine. The Veterinary Record,2001,148:473-477
114.Wu T, Chang H, Tan C, Bei W, Chen H. The orphan response regulator RevSC21 controls the attachment of Streptococcus suis serotype 2 to human laryngeal epithelial cells and the expression of virulence genes. Fems Microbiol Lett.2009, 292(2):170-181
115.Xiangan Han, Chengping Lu. Biological activity and identication of apeptide inhibitor of Lux From Streptococcus suis serotype 2. FEMS Microbiol Lett,2009, 294:16-23
116.Yih-Ling Tzeng, Charlene M K, Xinjian Zhang, David S S. MisR/MisS Two-Component Regulon in Neisseria meningitides.2008,76(2):704-716
117.Ying Ma, Youjun Feng, Di Liu, George F Gao. Serotype 2, severe Streptococcus suis Avian influenza virus, acute respiratory syndrome-coronavirus and beyond: molecular epidemiology, ecology and the situation in China. Phil Trans R Soc B, 2009 364,2725-2737
118.Y Wang, J H Sun, C P Lu. Purified Recombinant Phage Lysin LySMP:An Extensive Spectrum of Lytic Activity for Swine Streptococci. Curr Microbiol,2009, 58:609-615
119.Yuanyi Li, Marcelo G, Miriam E et al. Immunization with Recombinant Sao Protein Confers Protection against Streptococcus suis Infection. CLINICAL AND VACCINE IMMUNOLOGY,2007,14(8):937-943
120.Yu H J, Liu X C, Wang S W, Liu L G, Zu R Q, Zhong W J, Zhu X P, Xiang N J, Yuan H, Meng L, Ou Y B, Gao Y J, Lv Q, Huang Y, An X D, Huang T, Zhou X Y, Feng L, Pang Q D, Yang W Z. [Matched case-control study for risk factors of human Streptococcus suis infection in Sichuan Province, China. Zhonghua Liu Xing Bing Xue Za Zhi.2005,26(9):636-639
121.Yu H, Jing H, Chen Z, Zheng H, Zhu X, Wang H, Wang S, Liu L, Zu R, Luo L, Xiang N, Liu H, Liu X, Shu Y, Lee S S, Chuang S K, Wang Y, Xu J, Yang W. Human Streptococcus suis outbreak, Sichuan, China. Emerg Infect Dis.2006,12(6): 914-920