Seroprevalence and phylogenetic analysis of Toxoplasma gondii from domestic cats, captive wild felids, free-range wild felids and rats in certain regions of Thailand

Toxoplasmosis is an important zoonotic disease caused by Toxoplasma gondii, an obligated zoonotic apicomplexan parasite. The infection varies according to geographical areas. This work aimed to study the seroprevalence and genotype of T. gondii infection in domestic, captive and free-range wild felids, and in their small mammal prey, rats (Rattus spp). Two hundred and ninety three sera, received from the 4 individual animal groups in Thailand, were tested using the indirect latex agglutination test (ILAT) for specific antibody detection. The nested-PCR for glycerol-3-phosphate (B1) and bradyzoite surface antigen (SAG4) gene detection was used to detect seropositive animals and PCR product was submitted for DNA sequencing. Out of the 293 sera, ILAT showed 11.68% positive results. T. gondii were found 3.48% seropositive in the domestic cats (n=86), 18.84% seropositive in the captive wild felids (n=138), 14.28% seropositive in the free-range wild felids (n=7), and 6.67% seropositive in the murine prey (n=60). Tissues from the seropositive animals such as liver, heart, brain and skeletal muscle were collected, and then DNA was extracted to perform nested-PCR and sequence analysis. By the nested-PCR, the brain and muscle tissues received from 3 black rats and a clouded leopard (1.37%) were found positive for T. gondii. SAG4 and B1 might serve as novel genetic markers for population genetic studies of T. gondii isolates. Based on the ML phylogenetic tree analysis of SAG4 and B1 coding sequences, T. gondii found in 3 murine prey and a clouded leopard was close to T. gondii RH type I strain with approximately 99-100% similarity. This is the first report on the relation of T. gondii infection with strain identification in domestic cats, captive and free-range felids, and murine in Thailand. Better understanding of the genetic diversity will lead to better management, prevention and treatment of this disease in the valuable species of wild felids

Geographical distribution of Toxoplasma gondii genotypes in Asia: A link with neighboring continents

Defining the pattern of genetic diversity of Toxoplasma gondii is important to understand its worldwide distribution. During the last decades, a large number of studies have been published on Toxoplasma genotypes circulating in Europe, in North and South America. Two continents are still largely unexplored, Africa and, to a less extent, Asia. In this last continent, an increasing number of publications reported genotypes circulating in diverse provinces of China, but very few data are available for other Asian countries. After a systematic database search, 47 papers related to T. gondii genotypes in Asia were analyzed. Genetic characterization of DNA was performed by microsatellite markers, or more usually by a multiplex PCR using 11 PCR-RFLP markers, allowing data comparison to draw a first global picture of the population structure of this parasite throughout Asia. Overall, 390 isolates or DNA extracts were completely typed by PCR-RFLP and/or microsatellite marker methods, revealing 36 different PCR-RFLP or equivalent microsatellite genotypes: 15 genotypes identified by a ToxoDB number and 21 atypical or unique genotypes. The most common genotype found in Asia is the genotype ToxoDB#9 (Chinese 1). The clonal types I, II and II variant, and III were also commonly found in Asia. The geographical distribution of these genotypes across Asia may reflect either a continuum with Europe for the western part of Asia (presence of Type II), or the circulation of strains through animal migration or human activities between Africa and the Southwestern part of Asia (Africa 1 genotype in Turkey or ToxoDB#20 both I Sri-Lanka and in Ethiopia or Egypt). Although there are some indications of a genetic population structure in Southeast Asian countries different from the rest of Asia, more studies in this tropical part of Asia will be necessary for a region which represent as well as Africa one of the missing links of the T. gondii genetic diversity. (Résumé d'auteur