Wang Xiaolan, Cai Min, Jiang Wen, Wang Yuping, Jin Yue, Li Na, Guo Yaqiong, Feng Yaoyu, Xiao Lihua
School of Resources and Environmental Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China.
College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China.
Parasitol Res. 2017 Aug;116(8):2101-2110. doi: 10.1007/s00436-017-5509-8. Epub 2017 May 26.
Giardia duodenalis is a common parasitic protozoan in human and animals. Epidemiological and molecular data are available from dairy cattle in many industrialized countries, but information on genetic diversity at multiple genetic loci is limited, especially in pre-weaned dairy calves. In this study, 818 fecal specimens were collected from five dairy cattle farms located in suburbs of Shanghai, China, with two to five samplings per farm. G. duodenalis assemblages and subtypes were determined using multilocus genotyping (MLG) at the β-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) loci. The overall prevalence was 60.1% (492/818) combining data from the three genetic loci. Three G. duodenalis assemblages were detected, including E (n = 482), A (n = 5), and B (n = 1), with the concurrence of A and E in a few animals (n = 4). Intra-genotypic sequence diversity was high for assemblage E, showing 12, 13, and 17 subtypes at the bg, gdh, and tpi loci, including four, six, and eight new subtypes, respectively. All dominant subtypes (E3, E2, and E8 at the bg locus; E1 and E3 at the gdh locus; and E11 and E3 at the tpi locus) were detected on all farms at most sampling occasions, and only limited differences in subtype distribution were observed among five farms. Altogether, 58 assemblage E MLGs were identified, all of which had not been reported before, and seven (MLG-E1-MLG-E7) were each seen on multiple farms. These results indicate a high occurrence of G. duodenalis in dairy calves, the existence of high genetic heterogeneity of assemblage E on five farms, and frequent exchange of parasite populations among farms within a small geographic area. The clinical and epidemiologic significance of these observations warrants further investigations.
十二指肠贾第虫是人和动物中常见的寄生原生动物。许多工业化国家已有奶牛的流行病学和分子数据，但多个基因位点的遗传多样性信息有限，尤其是在断奶前的奶牛犊中。本研究从中国上海郊区的五个奶牛场收集了818份粪便标本，每个农场采样2至5次。使用β-贾第素（bg）、谷氨酸脱氢酶（gdh）和磷酸丙糖异构酶（tpi）基因座的多位点基因分型（MLG）来确定十二指肠贾第虫的组合和亚型。结合来自三个基因座的数据，总体患病率为60.1%（492/818）。检测到三种十二指肠贾第虫组合，包括E（n = 482）、A（n = 5）和B（n = 1），少数动物（n = 4）中同时存在A和E。组合E的基因型内序列多样性很高，在bg、gdh和tpi基因座分别显示出12、13和17个亚型，分别包括4个、6个和8个新亚型。所有优势亚型（bg基因座的E3、E2和E8；gdh基因座的E1和E3；tpi基因座的E11和E3）在大多数采样时间在所有农场均被检测到，五个农场之间仅观察到亚型分布的有限差异。总共鉴定出58种组合E的多位点基因型（MLG），所有这些之前均未报道过，其中七种（MLG-E1-MLG-E7）在多个农场均可见。这些结果表明奶牛犊中十二指肠贾第虫的高感染率，五个农场中组合E存在高度遗传异质性，并且在小地理区域内农场之间寄生虫种群频繁交换。这些观察结果的临床和流行病学意义值得进一步研究。
