[目的]了解云南省牛感染十二指肠贾第虫(Giardia duodenalis)的情况和基因型分布，评估贾第虫病的传播风险。[方法]采用巢式PCR方法基于十二指肠贾第虫的谷氨酸脱氢酶(gdh)基因对云南省3个地区采集的258份牛新鲜粪便样品进行检测，计算不同地区、不同年龄、不同品种牛的十二指肠贾第虫阳性率;对阳性样品进行测序，将测序结果提交至NCBI比对进行基因型鉴定;使用MrBayes 3。1程序进行贝叶斯推理法分析，采用普通时间可逆(general time reversible，GTR)替换模型，构建系统进化树。[结果]258份牛粪便样品中有23份呈十二指肠贾第虫阳性，总阳性率为8。91％(23/258)。其中，不同地区牛十二指肠贾第虫阳性率差异极显著(P＜0。01)，大理鹤庆县阳性率最高，为20。75％(11/53，95％CI=9。47～32。04);西双版纳勐海县和昭通永善县阳性率分别为8。82％(6/68，95％CI=1。91～15。74)、4。38％(6/137，95％CI=0。91～7。85);不同年龄牛十二指肠贾第虫阳性率差异极显著(P＜0。01)，犊牛(＜5月龄)阳性率(26。19％，11/42，95％CI=12。32～40。06)极显著高于成年牛(＞24月龄)(5。56％，12/216，95％CI=2。48～8。64);不同品种牛十二指肠贾第虫阳性率差异极显著(P＜0。01)，荷斯坦奶牛十二指肠贾第虫阳性率最高，为20。75％(11/53，95％CI=12。00～39。17)，黄牛、西杂牛(西门塔尔牛和本地黄牛的杂交品种)、西门塔尔牛阳性率较低，分别为17。86％(5/28，95％CI=2。73～32。98)、4。38％(6/137，95％CI=0。91～7。85)和2。50％(1/40，95％CI=0～7。56)。基于gdh基因序列分析23份十二指肠贾第虫阳性样品集聚体类型均是E型，但为7种不同基因亚型，其中6种亚型(E1、E12、E20、E30、E36和E38)与已知参考序列相似性为99。8％～100％，另一种亚型与未命名亚型参考序列相似性为99。8％。[结论]云南省牛存在十二指肠贾第虫感染，不同地区、不同年龄、不同品种牛的十二指肠贾第虫阳性率存在一定差异;集聚体主要为E型，且此类型在云南地区遗传多样性较高。
Infection Status of Giardia duodenalis in Cattle in Yunnan Province Based on gdh Gene
[Objective]This study was aimed to investigate the infection and genotype distribution of Giardia duodenalis(G.duodenalis)in cattle in Yunnan province,and evaluate the transmission risk of giardiasis.[Method]Nested PCR was used to detect fresh fecal samples of 258 cattle collected from three regions in Yunnan province based on the glutamate dehydrogenase(gdh)gene of G.duodenalis.The positive rates of G.duodenalis in different regions,ages,and breeds of cattle were calculated.Positive samples were sequenced,and the sequencing results were submitted to NCBI for genotype identification.MrBayes 3.1 was used in Bayesian inference analysis and construct a phylogenetic tree,choosing GTR(general time reversible)model.[Result]23 of 258 faecal samples were positive for G.duodenalis,and the total positive rate was 8.91％(23/258).The positive rates of G.duodenalis in cattle from different regions were extremely significantly different(P＜0.01),with the highest positive rate in Heqing county,Dali,at 20.75％(11/53,95％CI=9.47-32.04),the positive rates of Menghai county in Xishuangbanna and Yongshan county in Zhaotong were 8.82％(6/68,95％CI=1.91-15.74)and 4.38％(6/137,95％CI=0.91-7.85),respectively.The positive rates of G.duodenalis in cattle of different ages were extremely significantly different(P＜0.01).The positive rate in calves(＜5 months old)(26.19％,11/42,95％CI=12.32-40.06)was extremely significantly higher than that in adult cattle(＞24 months old)(5.56％,12/216,95％CI=2.48-8.64).There was an extremely significant difference in the positive rate of G.duodenalis among different breeds of cattle(P＜0.01).Holstein cows had the highest positive rate of G.duodenalis,which was 20.75％(11/53,95％CI=12.00-39.17).Yellow cattle,Western crossbred cattle(a hybrid of Simmental cattle and local Yellow cattle),and Simmental cattle had lower positive rates,which were 17.86％(5/28,95％CI=2.73-32.98),4.38％(6/137,95％CI=0.91-7.85)and 2.50％(1/40,95％CI=0-7.56),respectively.Based on the analysis of gdh gene sequence,23 positive samples of G.duodenalis were all assemblage E,but with 7 different subtypes.Among them,6 subtypes had a similarity of 99.8％to 100％with known reference sequences(E1,E12,E20,E30,E36 and E38),and another subtype had a similarity of 99.8％with unnamed reference sequences.[Conclusion]Cattle in Yunnan province were infected with G.duodenalis,with the positive infection rate varying with different regions,ages,and breeds of cattle.Assemblage E dominated the assemblages of G.duodenalis infection in cattle of Yunnan province,which possessed rich genetic diversity in Yunnan province.
万方数据
维普
