Infant rat infection modifies phenotypic properties of an invasive nontypeable Haemophilus influenzae

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• 作者：David Tsao^a ; Kevin L. Nelson^b ; Daniel Kim^b ; Arnold L. Smith^b ; ^{arnold.smith@seattlechildrens.org}
• 关键词：Animal infection ; Haemophilus influenzae ; Phase variation
• 刊名：Microbes and Infection
• 出版年：2012
• 期刊代码：65_12864579
• 类别：imm
• 出版时间：June, 2012
• 卷：14
• 期：6
• 页码：509-516
• 文件大小：194 K

摘要

Enhancing the virulence trait of a specific bacterium in an animal model is often performed prior to the use of the strain for m>ex聽vivom> human studies, such as reactivity with complement and antibody, or with phagocytic cells. For example, in m>Streptococcus pneumoniaem> mouse passage is used to enhance capsule production. While investigating an unusual serum-resistant unencapsulated m>Haemophilus influenzaem> (R2866), we found that animal passage yielded an isolate (R3392) which had decreased resistance to human serum, but increased virulence in Chang conjunctival cell monolayers, but with less invasion and transcytosis of polar H292 cells. We examined 90 colonies recovered from three infant rats for phase variants of LPS biosynthetic genes. In 88 colonies m>lgtCm> was OFF due to tetrameric repeat mediated slipped-strand mispairing at the time of DNA replication, while there was no variation in m>lic1Am>, m>lic2Am>, m>lic3Am>, m>lexAm> and m>oaf A.m> With m>lgtCm> OFF the LPS lacks Gal伪1-4尾Gal, an epitope mimicking the human p^k blood group, and molecular mimicry is lost. Selection for strain susceptible to NHS in the infant rat was not antibody mediated. We conclude that the passage of pathogens virulent in humans and animals may select for phenotypes only relevant for the animal species used.