Seroprevalence and Phylogenetic Analysis of Toxoplasma gondii from Domestic Cats, Captive Wild Felids, Free-range Wild Felids and Rats in Certain Regions of Thailand

Abstract

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.