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Title:   Author  item
                                            SHWAB, ELLIOT - University Of Tennesseeitem
                                            JIANG, TIANTIAN - University Of Tennesseeitem
                                            PENA, HILDA - Universidade De Sao Pauloitem
                                            GENNARI, SOLANGE - Universidade De Sao Pauloitem
                                            Dubey, Jitenderitem
                                            SU, CHUNLEI - University Of Tennessee
  Submitted to: International Journal for Parasitology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 10/21/2015
                                    Publication  Date: 12/14/2015
                                    Citation: Shwab, E.K., Jiang, T., Pena, H.F., Gennari, S.M., Dubey, J.P., Su, C. 2015. The ROP18 and ROP5 allele types are highly predictive of mouse-virulence across globally distributed strains of Toxoplasma gondii. International Journal for Parasitology. 46:141-146.Interpretive Summary: Toxoplasma gondii is a single-celled parasite of all warm-blooded hosts worldwide. It causes mental retardation and loss of vision in children, and abortion in livestock. Cats are the main reservoir of T. gondii because they are the only hosts that can excrete the resistant stage (oocyst) of the parasite in the feces. Humans become infected by eating under cooked meat from infected animals and food and water contaminated with oocyst. Why some people become ill and even die from toxoplasmosis whereas others remain asymptomatic is largely unknown. The genetic characteristics of T. gondii strains are considered a factor in the pathogenesis on clinical disease. The underlying mechanism for the parasite virulence is also not fully understood. In the present study the authors found that certain genes (ROP 5 and ROP 18) affect the virulence of the parasite. The results will be useful for parasitologists, biologists, and epidemiologists.
                                Technical Abstract: The protozoan parasite Toxoplasma gondii is one of the known most successful eukaryotic pathogens on Earth. Virulence of T. gondii strains varies greatly in mice, and mounting evidence suggests that such variations may be relevant to the manifestation of human toxoplasmosis. Polymorphic rhoptry-secreted kinases and pseudokinases (ROP) have been demonstrated to account for murine virulence among the archetypal clonal parasite lineages that dominate the populations of North America and Europe. However, the distribution of virulence gene alleles in natural populations and the broad influence of these allele combinations on T. gondii virulence have not been examined in depth. In the present study, we have performed PCR-RFLP genotyping analysis on a diverse array of globally distributed T.gondii strains at four ROP gene loci including ROP18, ROP5, ROP16 and ROP17 that previously implicated in influencing T. gondii virulence and pathogenesis. We demonstrate through correlation with published virulence data that the combination of ROP18 and ROP5 allele types is highly predictive of T. gondii virulence across a broad range of global T. gondii isolates. These findings indicate that the importance of ROP18 and ROP5 in determining strain virulence is not limited to the North American/European archetypal lineages most commonly used in molecular studies, but also appears to apply to diverse isolates from South/Central America and Asia. RFLP analysis of these loci may thus serve as a valuable tool in determining the potential virulence of uncharacterized T. gondii strains in future studies.


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