Molecular Detection And Identification Of Giardia Duodenalis In Sheep In Some Large-scale Farms In Southern Xinjiang

With the development of economy,sheep breeding accounts for an increasing proportion of animal husbandry in China.G.duodenalis infection is common in sheep all over the world.In this study,molecular biological methods were used for detection,sequence analysis and genetic structure analysis of G.duodenalis to understand the infection status and molecular genetic characteristics of G.duodenalis in sheep in some large-scale farms in southern Xinjiang.In order to provide basic data for the prevention and control of giardiasis in sheep in China.(1)A total of 767 sheep fecal fecal DNA samples from 6 large-scale farms in southern Xinjiang were detected by PCR based on SSU r RNA gene locus.The results showed that the total infection rate of G.duodenalis in sheep was 17.5%(134/767)and all 6 farms tested positive.Among different sampling points,the highest infection rate was 23.1%(25/108)in sheep of Wensu County,the infection rate in sheep in Yutian County,Alaer City,Kuqa City,Qira County and Shufu County were23.0%(48/209),18.9%(17/90),17.1%(18/105),16.7%(25/150)and 1.0%(1/105),respectively.The infection rates of G.duodenalis in sheep at different sampling points was significantly different(P≤0.01).Among different age groups,the highest infection rate was 26.8%(56/209)in sheep aged3 ～ 6 months,followed by aged <3 months and 7 ～ 12 months were 18.2%(32/176)and 18.1%(32/177),the lowest infection rate was 6.8%(14/205)in sheep aged >12 months.The infection rates of G.duodenalis in sheep at different ages was significantly different(P≤0.01).134 positive PCR products of G.duodenalis were sequenced and identified as assemblage E by sequence alignment.The results showed that host specific assemblage E of G.duodenalis was common in sheep in large-scale farms in southern Xinjiang.(2)Based on glutamate dehydrogenase(gdh),triose phosphate isomerase(tpi)and β-giardin(bg)gene locus,134 positive isolates of G.duodenalis from sheep were genotyped by PCR,106,92 and 98 positive products were successfully amplified,respectively.After sequencing and comparing the positive products,4,8 and 12 gene subtypes were obtained at the gdh,tpi and bg gene locus,named g E1 ～ g E4,t E1 ～ t E8 and b E1 ～ b E12.A total of 14 isolates of G.duodenalis were successfully amplified at three gene locus,forming 10 multipoint genotypes,named MLG E1～MLG E10,forming5 subpopulations.After germline development analysis,there are genetic differences between the multipoint genotypes of assemblage E in this study and the multi locus genotype detected in sheep in Qinghai Province and Henan Province,MLG E3～MLG E10 were new multipoint genotypes.The results suggest that G.duodenalis from sheep in southern Xinjiang has the characteristics of geographical regional distribution and genetic diversity.In conclusion,G.duodenalis infection was common in some large-scale sheep farms in southern Xinjiang,the highest infection rate of G.duodenalis in sheep was aged 3～6 months among different ages.One kind of assemblage E was identified and has the characteristics of geographical regional distribution and genetic diversity after germline development analysis.The results of this study suggest that G.duodenalis should be detected regularly in large-scale sheep farms,so as to ensure the healthy development of sheep breeding industry in southern Xinjiang.