Asexual expansion of Toxoplasma gondii merozoites is distinct from tachyzoites and entails expression of non-overlapping gene families to attach, invade, and replicate within feline enterocytes
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- 作者：Adrian B Hehl (1)
Walter U Basso (1)
Christoph Lippuner (1) (2)
Chandra Ramakrishnan (1)
Michal Okoniewski (3)
Robert A Walker (1) (4)
Michael E Grigg (5)
Nicholas C Smith (4)
Peter Deplazes (1)
1. Institute of Parasitology-University of Zurich ; Winterthurerstrasse 266a ; Z眉rich ; 8057 ; Switzerland
2. Current address ; Department of Anaesthesiology and Pain Medicine ; Inselspital ; University of Bern ; Freiburgstrasse ; Bern ; 3010 ; Switzerland
3. Functional Genomics Center Zurich ; Winterthurerstrasse 190 ; Z眉rich ; 8057 ; Switzerland
4. Queensland Tropical Health Alliance Research Laboratory ; Faculty of Medicine ; Health and Molecular Sciences ; James Cook University ; Cairns Campus ; McGregor Road ; Smithfield ; QLD ; 4878 ; Australia
5. Molecular Parasitology Section ; Laboratory of Parasitic Diseases ; NIAID ; NIH ; Bethesda ; Maryland ; USA - 关键词：Toxoplasma gondii ; Apicomplexa ; Coccidia ; Cat ; Enteroepithelial development ; Merozoite ; Schizont ; Comparative transcriptomics ; Surface antigen ; Stage ; specific gene expression
- 刊名：BMC Genomics
- 出版年：2015
- 出版时间：December 2015
- 年：2015
- 卷：16
- 期：1
- 全文大小：2,187 KB
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- 出版者：BioMed Central
- ISSN：1471-2164
文摘
Background The apicomplexan parasite Toxoplasma gondii is cosmopolitan in nature, largely as a result of its highly flexible life cycle. Felids are its only definitive hosts and a wide range of mammals and birds serve as intermediate hosts. The latent bradyzoite stage is orally infectious in all warm-blooded vertebrates and establishes chronic, transmissible infections. When bradyzoites are ingested by felids, they transform into merozoites in enterocytes and expand asexually as part of their coccidian life cycle. In all other intermediate hosts, however, bradyzoites differentiate exclusively to tachyzoites, and disseminate extraintestinally to many cell types. Both merozoites and tachyzoites undergo rapid asexual population expansion, yet possess different effector fates with respect to the cells and tissues they develop in and the subsequent stages they differentiate into. Results To determine whether merozoites utilize distinct suites of genes to attach, invade, and replicate within feline enterocytes, we performed comparative transcriptional profiling on purified tachyzoites and merozoites. We used high-throughput RNA-Seq to compare the merozoite and tachyzoite transcriptomes. 8323 genes were annotated with sequence reads across the two asexually replicating stages of the parasite life cycle. Metabolism was similar between the two replicating stages. However, significant stage-specific expression differences were measured, with 312 transcripts exclusive to merozoites versus 453 exclusive to tachyzoites. Genes coding for 177 predicted secreted proteins and 64 membrane- associated proteins were annotated as merozoite-specific. The vast majority of known dense-granule (GRA), microneme (MIC), and rhoptry (ROP) genes were not expressed in merozoites. In contrast, a large set of surface proteins (SRS) was expressed exclusively in merozoites. Conclusions The distinct expression profiles of merozoites and tachyzoites reveal significant additional complexity within the T. gondii life cycle, demonstrating that merozoites are distinct asexual dividing stages which are uniquely adapted to their niche and biological purpose.