Molecular Epidemiological Investigation Of Giardia Duodenalis In Dairy Cows In Part Of Inner Mongolia

Giardia duodenalis,a common zoonotic parasitic protozoa,exists all over the world.Generally,it is divided into eight aggregates from A to H.Cows can usually be infected with three aggregates,namely A,B and E.Among them,the detection rate of Agglomerate E is the highest in dairy cow samples.In order to understand the epidemic situation and gene distribution characteristics of G.duodenalis of dairy cows in some areas of Inner Mongolia,samples were collected from dairy farms and retail dairy farmers in some areas of Inner Mongolia from March 2021 to September 2021,and the infection of G.duodenalis of dairy cows in Inner Mongolia was analyzed through molecular epidemiological investigation.Based on the small subunit ribosomal RNA(Small subunit ribosomal RNA,SSU r RNA)gene locus of G.duodenalis,505 samples collected from dairy farms in some areas of Inner Mongolia were detected by nested PCR.149 positive samples were detected,and the total infection rate was 29.5%.,which(43.1%)was more common after weaning than before weaning(10.68%),and the infection rates of dairy cows of different ages were significantly different(P<0.01).Through two-way sequencing,BLAST was selected for homology search,and the obtained sequence reference sequencing map was compared and corrected by software such as Snap Gene and MEGA.Finally,146 trusted sequences were obtained.Two kinds of aggregates are identified: aggregate E(n=133)and aggregate A(n=13).Agglomerate E is the dominant genotype of Giardia infection in dairy cows in the sampling area,accounting for 91.10%(133/146)of the total positive rate.Based on the glutamate dehydrogenase(glutamate dehydrogenase,gdh),Triose phosphate isomerase(Triose phosphate isomerase,tpi)and β-Giardia(β-Giardia,bg)gene sites of Giardia,149 positive samples were amplified by nested PCR with specific primers.52,52 and 75 positive samples were obtained respectively,with the positive rates 34.90%(52/149),34.90%(52/149)and 50.33%(75/149).The obtained positive sequences were compared and corrected by software analysis,and phylogenetic tree was constructed.Through the analysis of the positive sequences of SSU rRNA genes,the dominant gene of G.duodenalis infection in dairy cows in Inner Mongolia was the aggregate E(88.59%,132/149),followed by the mixed infection among aggregate(A+E)(5.36%,8/149),and aggregate A(4.02%,6/149).The multi-locus genotyping(MLG)method was used to identify the subtypes of the Giardia gene in dairy cows in some areas of Inner Mongolia.The results showed that there were many MLGs in the Giardia aggregate E in this area,and six subgroups were formed.This paper is the first to conduct a large-scale investigation on the infection,genes and subtype distribution characteristics of G.duodenalis in dairy cows in Inner Mongolia.The predominant genotype of G.duodenalis infection among dairy cows in some areas of Inner Mongolia is aggregate E.There is a mixed infection of aggregate A and aggregate E,which clarifies the genetic diversity of G.duodenalis in dairy cows in this area,fills the gap in the study of G.duodenalis from Inner Mongolia,and provides a solid foundation for the study of Giardia duodenum in this area.The foundation of pest control is laid.