Serological Investigation Of Viral Infectious Diseases And Nested-PCR Detection Of Enterocytozoon Bieneusi In Yaks And Tibetan Sheep In China

Yaks(Bos grunniens)and Tibetan sheep(Ovis aries)are important original animals in China,and they mainly live in Tibetan Plateau.Yaks and Tibetan sheep are important economic source for the locals because of the high quality meat and the milk.Bovine viral diarrhoea(BVD),Bluetongue(BT),Enzootic bovine leukosis(EBL)and Border disease(BD)are important diseases of animals and can cause huge economic loss to the animal industry.Enterocytozoon bieneusi,the important zoonotic pathogen,has been reported in various animals and humans.Bovine viral diarrhoea virus(BVDV)is an important pathogen of cattle and sheep worldwide,a member of Pestivirus genus,within the Flaviviridae family.It could be divided into bovine viral diarrhoea(BVD)and mucosal disease(MD)according to clinical symptoms.BVDV has associated with pathology in several body systems including the respiratory,immunodepression and reproductive systems.BT,an infectious but non-contagious arthropod-borne viral disease in domestic ruminants,is caused by Bluetongue virus(BTV).BTV infection in animals usually present as symptoms of fever,marasmus,nasal discharge,drooling of saliva,oral lesion,oral and gastric mucosa ulcers.It could cause significant economic losses.Enzootic bovine leukosis(EBL)is a chronic lymphosarcoma disease of cattle caused by bovine leukemia virus(BLV).BLV infections may present as aleukemic(asymptomatic animals),persistent lymphocytosis(with hematological abnormalities)and lymphosarcoma(tumors),and usually accompanies higher mortality.Border disease(BD)is congenital disorders in sheep caused by border disease virus(BDV).BDV infection in animals usually present as symptoms of reproductive disorder,lamb abnormality and growth retarded.It could cause significant economic losses.Enterocytozoon bieneusi,the most common zoonotic pathogen of microsporidiosis,has been found in various animals and humans.Enterocytozoon bieneusi is the important pathogen of opportunistic infection in animals and humans of low immunity status,and may lead to death.In the first part of this study,the seroprevalence of antibodies to BVDV,BTV,BLV and BDV infection in yaks and Tibetan sheep in northwest China were examined by the enzyme-linked immunosorbent assay(ELISA).It was demonstrated that 595(37.56%)out of 1584 serum samples in yaks were BVDV seropositive,804(36.76%)out of 2 187 serum samples in Tibetan sheep were BVDV seropositive.According to conditional forward stepwise logistic regression,a significant difference has been found between Tibetan sheep and yak groups(P< 0.05).211(13.32%)out of 1 584 serum samples in yaks were BTV seropositive,443(20.26%)out of 2 187 serum samples in Tibetan sheep were BTV seropositive,and the species were considered as risk factors analyzed by logistic regression model.334(21.09%)out of 1584 serum samples in yaks were BLV seropositive,the species and regions were considered as risk factors.400(18.29%)out of 2 187 serum samples in Tibetan sheep were BDV seropositive,and no risk factors has been identified.Second,we studied E.bieneusi prevalence in yaks and Tibetan sheep in northwest China by nested PCR.Of the 471 yak faecal samples,9(1.91%)were E.bieneusi-positive,and 0(0%)out of 496 Tibetan sheep faecal samples were E.bieneusi-positive.A total of 4 genotypes,including 3 known genotypes(genotypes I,D and BEB4)and one novel genotype(named WCY1),were identified in the present study.In conclusion,this study investigated the seroepidemiology of BVDV,BTV,BLV and BDV and molecular epidemiology of E.bieneusi in yaks and Tibetan sheep in northwest China.These data provide base-line information for the prevention and control of these infectious diseases,and these have important public health significance.