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Sequence variation in Toxoplasma gondii rop17 gene among strains from different hosts and geographical locations.

ABSTRACT: Genetic diversity of T. gondii is a concern of many studies, due to the biological and epidemiological diversity of this parasite. The present study examined sequence variation in rhoptry protein 17 (ROP17) gene among T. gondii isolates from different hosts and geographical regions. The rop17 gene was amplified and sequenced from 10 T. gondii strains, and phylogenetic relationship among these T. gondii strains was reconstructed using maximum parsimony (MP), neighbor-joining (NJ), and maximum likelihood (ML) analyses. The partial rop17 gene sequences were 1375 bp in length and A+T contents varied from 49.45% to 50.11% among all examined T. gondii strains. Sequence analysis identified 33 variable nucleotide positions (2.1%), 16 of which were identified as transitions. Phylogeny reconstruction based on rop17 gene data revealed two major clusters which could readily distinguish Type I and Type II strains. Analyses of sequence variations in nucleotides and amino acids among these strains revealed high ratio of nonsynonymous to synonymous polymorphisms (>1), indicating that rop17 shows signs of positive selection. This study demonstrated the existence of slightly high sequence variability in the rop17 gene sequences among T. gondii strains from different hosts and geographical regions, suggesting that rop17 gene may represent a new genetic marker for population genetic studies of T. gondii isolates.

SUBMITTER: Zhang NZ

PROVIDER: S-EPMC4121216 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Sequence variation in Toxoplasma gondii rop17 gene among strains from different hosts and geographical locations.

Zhang Nian-Zhang NZ Xu Ying Y Huang Si-Yang SY Zhou Dong-Hui DH Wang Rui-Ai RA Zhu Xing-Quan XQ

TheScientificWorldJournal 20140710

Genetic diversity of T. gondii is a concern of many studies, due to the biological and epidemiological diversity of this parasite. The present study examined sequence variation in rhoptry protein 17 (ROP17) gene among T. gondii isolates from different hosts and geographical regions. The rop17 gene was amplified and sequenced from 10 T. gondii strains, and phylogenetic relationship among these T. gondii strains was reconstructed using maximum parsimony (MP), neighbor-joining (NJ), and maximum lik ...[more]

PMID: 25126596

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Project description:BackgroundToxoplasma gondii has a largely clonal population in North America and Europe, with types I, II and III clonal lineages accounting for the majority of strains isolated from patients. RH, a particular type I strain, is most frequently used to characterize Toxoplasma biology. However, compared to other type I strains, RH has unique characteristics such as faster growth, increased extracellular survival rate and inability to form orally infectious cysts. Thus, to identify candidate genes that could account for these parasite phenotypic differences, we determined genetic differences and differential parasite gene expression between RH and another type I strain, GT1. Moreover, as differences in host cell modulation could affect Toxoplasma replication in the host, we determined differentially modulated host processes among the type I strains through host transcriptional profiling.ResultsThrough whole genome sequencing, we identified 1,394 single nucleotide polymorphisms (SNPs) and insertions/deletions (indels) between RH and GT1. These SNPs/indels together with parasite gene expression differences between RH and GT1 were used to identify candidate genes that could account for type I phenotypic differences. A polymorphism in dense granule protein, GRA2, determined RH and GT1 differences in the evasion of the interferon gamma response. In addition, host transcriptional profiling identified that genes regulated by NF-ĸB, such as interleukin (IL)-12p40, were differentially modulated by the different type I strains. We subsequently showed that this difference in NF-ĸB activation was due to polymorphisms in GRA15. Furthermore, we observed that RH, but not other type I strains, recruited phosphorylated IĸBα (a component of the NF-ĸB complex) to the parasitophorous vacuole membrane and this recruitment of p- IĸBα was partially dependent on GRA2.ConclusionsWe identified candidate parasite genes that could be responsible for phenotypic variation among the type I strains through comparative genomics and transcriptomics. We also identified differentially modulated host pathways among the type I strains, and these can serve as a guideline for future studies in examining the phenotypic differences among type I strains.

Dataset Information

Sequence variation in Toxoplasma gondii rop17 gene among strains from different hosts and geographical locations.

Publications

Sequence variation in Toxoplasma gondii rop17 gene among strains from different hosts and geographical locations.

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