Study On Population Structure Of Cyptosporidium Spp.and Giardia Lamblia In Calves From Partial Areas Of Shaanxi

Cryptosporidium spp.and Giardia lamblia are two important opportunistic enteric protozoa,which have been detected in many countries and regions in the world.Both Cryptosporidium and G.lamblia have wide host ranges,including humans and various animals,and they are greatly harmful for human health and the production performance of animals.Since cattle are important economic animals in Shaanxi province,it's necessary to investigate the prevalence and population structures of these pathogens in order to obtain basic information and data.In the present study,the infection status of Cryptosporidium and G.lamblia in calves from partial Shaanxi province was investigated using the nested PCR technology,and the population structure of these parasites were identified.The main results were listed as follows:1.PCR targeting the 18 S rRNA gene locus of Cryptosporidium was used to detect 371 faecal samples(198 from dairy calves and 173 from Qinchuan calves)collected from calves in Yangling,Xianyang,Tongchuan,Hanzhong,Baoji and Weinan of Shaanxi province.The overall infection rate was 23.18%(86/371),with 31.31%(62/198)in dairy calves and 13.87%(24/173)in Qinchuan calves,and 25.00%(50/200)in pre-weaned(one to two months)calves and 21.05%(36/171)in post-weaned(three to six months)calves.Of 86 Cryptosporidium-positive samples,36 samples were identified as C.andersoni,21 as C.ryanae and 29 as C.bovis.The MLST analysis was conducted at the gene loci of MS1,MS2,MS3 and MS16 among 36 C.andersoni isolates,revealing 15 samples which were successfully amplified at four loci,forming 3,1,2,1 subtypes,respectively.Four MLST subtypes in this study were all identified in post-weaned calves.2.Three hundred and seventy-one(198 from dairy calves and 173 from Qinchuan calves)faecal samples were collected from calves in Yangling,Xianyang,Tongchuan,Hanzhong,Baoji and Weinan in Shaanxi province and used for detecting the infection of G.lamblia.The overall prevalence was 18.87%(70/371),with 20.71%(41/198)in dairy calves and 16.76%(29/173)in Qinchuan calves,and 20.00%(40/200)in pre-weaned(one to two months)calves and 17.54%(30/171)in post-weaned(three to six months)calves.Assemblages E(62/70)and A(8/70)were identified by the sequence alignment of the TPI gene.Seventeen assemblage E subtypes(E1 to E17),including five novel subtypes(named as E13 to E17),and one assemblage A subtype were identified.Thirty-seven samples were successfully amplified at gene loci of TPI,BG,GDH and SSU rRNA,forming nine,nine,five and two assemblage subtypes,respectively.Twenty-five MLGs were identified,containing 22 assemblage E MLGs in dairy and Qinchuan calves,one assemblage A MLG in pre-weaned dairy calf and two co-infected MLGs in dairy calves.