| Giardia duodenalis is an important intestinal parasitic protozoan that can infect a wide range of vertebrates,including humans,domestic animals,and wildlife.As an important host of Giardia duodenalis,cattle infected with Giardia duodenalis can cause both economic losses to livestock industry and human health hazards.In this study,we investigated Giardia duodenalis in some areas of Shanxi using molecular biology methods,aiming to understand the infection status of Giardia duodenalis in dairy and beef cattle in some areas of Shanxi and its genetic characteristics.Based on the specific gene loci of Giardia duodenalis,858 dairy and beef cattle manure samples from 6 large-scale farms and some retail farmers in some areas of Shanxi were tested and sequenced using the Chao PCR method.The results showed that the total infection rate of Giardia duodenalis in dairy and beef cattle in some areas of Shanxi was31.24%(268/858),with the highest infection rate in Lingqiu dairy farm 3(57.14%,40/70)and the lowest infection rate in Lingqiu dairy retailer 3(10.00%,10/100),with statistically significant differences in Giardia duodenalis infection rates in cattle at different sampling points(P <(P < 0.01);the highest infection rate of Giardia duodenalis was found in cattle from 61 to 180 d(53.13%,68/128)and the lowest in cattle from 0 to 60 d(22.92%,11/48),with statistically significant differences in Giardia duodenalis infection rates in cattle of different ages(P < 0.01);the infection rate of Giardia duodenalis in cattle from farms(38.78% 185/477)was higher than the infection rate of Giardia duodenalis in retail cattle(21.78%,83/381),with highly significant differences in statistical analysis(P < 0.01);the positive rate of Giardia duodenalis in cattle diarrhea samples(34.46%,51/148)was slightly higher than that in non-diarrhea samples(30.56%,217/710),with insignificant differences in statistical analysis(P >0.05);the prevalence of Giardia duodenalis infection in cows(28.84%,107/371)was slightly lower than that of Giardia duodenalis infection in beef cattle(33.06%,161/487),and the difference was not significant in statistical analysis(P >0.05).The obtained 127 segments of ribosomal small subunit RNA(SSU r RNA)gene sequences identified a total of 2 aggregates,aggregate A(n=8)and aggregate E(n=119),and aggregate E(93.70%,119/127)was the dominant infection aggregate.Nested PCR amplification was performed based on the Giardia duodenal β-giardifolin(bg),glutamate dehydrogenase(gdh)and prolyl phosphate isomerase(tpi)gene loci,and83,53 and 59 sequences were obtained,respectively.Sequence analysis revealed 20 genetic isoforms at the bg locus,including 1 genetic isoform at cluster A(n=2)and 19 genetic isoforms at cluster E(n=81);23 genetic isoforms at the gdh locus,including 1genetic isoform at cluster A(n=1)and 22 genetic isoforms at cluster E(n=52);32 genetic isoforms at the tpi locus There were 32 genetic isoforms at the tpi locus,of which 1 genetic isoform existed at cluster A(n=2)and 31 genetic isoforms existed at cluster E(n=57).A total of 29 Giardia duodenal isolates were successfully amplified at three loci simultaneously,forming 29 MLGs,and 10 subgroups were formed by germline developmental analysis.This study was the first to investigate the distribution characteristics of Giardia duodenalis infections and aggregate subtypes in dairy and beef cattle in some areas of Shanxi,and found that there were two types of aggregates(aggregate A and aggregate E),with aggregate E being the dominant aggregate type,indicating that Giardia duodenalis has a zoonotic risk and genetic diversity in cattle in the region,providing basic data and laying the foundation for the prevention and control of Giardia duodenalis in cattle in Shanxi. |
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