Antibody Detection, Isolation, Genotyping, and Virulence of Toxoplasma gondii in Captive Felids from China

Abstract

The felids are the only definitive hosts of <i>Toxoplasma gondii</i>, which could excrete oocysts into the environment and provide an infection source for toxoplasmosis in various warm-blooded animal species, particularly the captive felids that live close to human communities. The infection rate of the captive felids is a perfect standard in detecting the presence of <i>Toxoplasma gondii</i> oocysts in the environment. In this study, sera or tissue samples from zoo (1 young tiger, 2 adult tigers, 6 young lions), farm (10 masked palm civets), and pet hospital (28 cats) from Henan Province (China) were collected. The sera (<i>n</i> = 47) were tested for immunoglobulin G (IgG) antibodies against <i>T. gondii</i> by using modified agglutination test (MAT), whereas the hearts tissue (<i>n</i> = 40) were bioassayed in mice to isolate <i>T. gondii</i> strains. The genotype was distinguished by using PCR-RFLP of 10 loci (SAG1, SAG2, SAG3, GRA6, BTUB, L358, c22-8, PK1, c29-2, and Apico). The detection rate for the <i>T. gondii</i> antibody in captive felids was 21.3% (10/47). One viable <i>T. gondii</i> strain (TgCatCHn4) was obtained from a cat heart tissue, and its genotype was ToxoDB#9. The oocysts of ToxoDB#9 were collected from a <i>T. gondii</i>-free cat. The virulence of TgCatCHn4 was low and no cysts were detected in the brain of mice at 60 days post-inoculation. The finding of the present study suggested a widespread exposure of <i>T. gondii</i> for felids in Henan Province of central China, particularly those from the zoological gardens and homes. ToxoDB#9 was the predominant strain in China. Preventive measures against <i>T. gondii</i> oocyst contamination of various components of the environment should thus be implemented, including providing pre-frozen meat, well-cooked cat food, cleaned fruits and vegetables, monitoring birds and rodents, inactive <i>T. gondii</i> oocysts in felids feces, and proper hygiene.