Parasitology

Biography

Biography: Jilong Shen

Abstract

Toxoplasma gondii is an obligatory intracellular protozoon capable of infecting a wide range of mammalian hosts including humans. It has been found that European and North American strains of the parasite show a clonal population structure with three distinct lineages(types I, II, and III) while strains isolated from animals and humans in South America present a high genetic diversity. The strains with these genotypes differ in virulence and in distinct host response due to the effectors polymorphisms of ROP16 and GRA15. We collected 59 strains of T. gondii from stray cats, free-range chicken, and pork in retail meat stores. The PCR-RFLP at 9 loci and microsatellite typing at 15 markers were used for genotyping; finally, seven genotypes were identified (type I, type II, ToxoDB#9, #203, #205, #213, and #215). We also found that the majority of isolates from both animals and humans (the cancer patients with a long term of chemotherapy) belong to type Chinese 1 (ToxoDB#9), acounting for 74.58%(44/59). Phenotypical examinations indicated a significantly different virulence in mice and parasite proliferation in cultures cells among the isolates with Chinese 1. Additionally, sequencing of effectors ROP16 and GRA 15 demonstrated that strains of Chinese 1 with different virulence share the ROP16I/III polymorphysm with type I/III and GRA15II with type II. Our results suggest that the genetic markers currently used for genotyping failed to identify the virulence of strains with Chinese 1, and it may have the pathogenesis different from that of the archetypal strains in European and North America.