| Toxoplasma gondii is a zoonotic intracellular coccidian parasite infects virtually all warm-blooded animals,including birds,humans,livestock and wildlife.Cats are both intermediate and definitive hosts of T.gondii,and they can excrete the oocysts of T.gondii into the environment with their feces,resulting in the transmission of T.gondii.For most hosts,T.gondii infection is usually asymptomatic or subclinical.Kangaroos are susceptible to T.gondii infection,and as herbivorous animals,the infection of T.gondii in kangaroos can provide an early warning of the contamination of the surrounding environment by T.gondii.However,there is little information on T.gondii infection in captive kangaroos in China.A total of 33 kangaroo samples were collected in this study from 2017 to 2022,including tissue samples and serum samples,among which 16 dead kangaroo samples were collected from Henan Zoo from 2017 to 2020,17 kangaroo serum samples were collected from Shandong and Henan provinces in 2021 to 2022.This study investigated the prevalence of T.gondii infection in captive kangaroo populations in central China,so as to provide a reference for the prevention and control of T.gondii infection in marsupials and provide a warning for the risk of T.gondii transmission.In addition,the molecular biological characteristics of T.gondii isolates from kangaroos also provide basic data for the study of the distribution,population evolution,transmission and control of T.gondii in China.T.gondii antibody was detected in 54.5%(18/33,95%CI: 37.98-70.16)of the kangaroo serum samples collected from central China by modified agglutination test(MAT).It was found that the infection rate of white kangaroos was higher than that of other kangaroos,and the infection rate of female kangaroos was higher than that of male kangaroos(P = 0.0366).The infection rate of kangaroos with basic diseases was higher than that of normal kangaroos(P = 0.2801),and heavy rain was a risk factor for the transmission of T.gondii(P = 0.0244).Four viable T.gondii strains,named Tg Roo CHn1,Tg Roo CHn2,Tg Roo CHn3 and TgRooCHn4,were successfully isolated from 16 kangaroo tissue samples by mouse bioassay.The four isolates were genotyped and identified for virulence by PCR-RFLP,Tg Roo CHn1 is Toxo DB# 292(atypical),Tg Roo CHn2 and Tg Roo CHn4 are Toxo DB# 3(type II).Tg Roo CHn3 is Toxo DB# 2(type III).Through the identification of virulence proteins ROP18/ROP5 and the evaluation of virulence in mice,the results showed that Tg Roo CHn1 and Tg Roo CHn4 were avirulent strains,and Tg Roo CHn2 and Tg Roo CHn3 were moderate virulent strains,which could establish chronic infection in mice and form T.gondii cysts in the brain of mice.In this study,four viable T.gondii strains were isolated from a captive kangaroos in China,and one of them was a new genotype(Toxo DB# 292).In addition,this is the first viable T.gondii strain isolated from a white kangaroo,which has enriched the genetic and host diversity of T.gondii.The high prevalence of T.gondii infection in captive kangaroos indicates the urgent need to control the spread of this parasite in the environment,food,and water of animals in zoos.Improvemets for captive settings were initiated,including greater attention being paied to birds and stray cats,fed frozen meat for carnivores. |
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