Seraprevalance Of Toxoplasma Infection And Genotyping Of The Isolates From Cancer Patients In Anhui, Eastern China

Objective To reveal Toxoplasma gondii infection and characterize the genotypes of T.gondii strains from cancer patients in Anhui province.Methods Toxoplasma-specific Ig G and Ig M antibodies were tested in 356 cancer patients by using enzyme-linked immunosorbent assays(ELISA). The positive samples by ELISA were subjected to Toxo-DNA detection with PCR targeting 529 bp repeat sequences of T. gondii. The samples from PCR-positive individuals were genotyped with the multilocus PCR-RFLP method. The PCR-RFLP positive Toxo-genomic DNAs were subjected to PCR amplification again for ROP16 and GRA15, both are believed to be the strain-virulence associated effectors. The PCR-generated products were sequenced to observe the polymorphisms that have been verified to initiate the distinct macrophage polarization and the host innate immunity against the parasite.Results Antibodies against Toxoplasma were examined in serum samples. Twenty one(5.90%) cases were found to be Ig G-positive and eight(2.25%) were Ig M-positive in the cancer patients. Six PCR-positive samples were genotyped at 10 loci and two of them were successfully photographed with all genetic markers and both belong to the genotype of Chinese 1(Toxo DB#9). Additional polymorphic analyses of both ROP16 and GRA15 by DNA sequencing showed that type Chinese 1 strain shares the polymorphic ROP16I/III with type I(RH) and type III strains, and GRA15 II with type II strain(PRU), suggesting a pathogenesis of type Chinese 1 strain different from that of archetypal clonal lineage which dominates in Europe and North America.Conclusion Both latent Toxoplasma infection and parasitemia of activated toxoplasmosis exist in the patients with malignant tumors and the predominant genotype of isolates from humans is Chinese 1(Toxo DB#9), which coincides with the strain type predominantly circulating in animals of China. The common polymorphic loci of ROP16 I/III and GRAII effectors suggest that human derived Chinese 1 strainmight possess the unique pathogenic features in induction of macrophage polarization and host innate immunity against T.gondii infection...