中国南海周边犬类贾第虫感染情况调查与基因序列分型

贾第虫是一种人兽共患肠道寄生原虫,在全世界范围内传播,其感染率与地区和环境有非常大的关系。为了解中国南海周边国家和地区犬类贾第虫感染情况,判断海洋隔离是否是影响贾第虫传播的重要因素,自2018年6月至2019年7月,从中国广州、越南胡志明市、马来西亚吉隆坡、新加坡和菲律宾马尼拉分别采集犬类粪便样本616份。提取每个地区犬类粪便样本的DNA,以贾第虫磷酸丙糖异构酶(triose phosphate isomerase)基因TPI和BG(genotyping at the beta giardin)基因制作巢式PCR引物。提取的犬粪基因组DNA为模板进行巢式PCR扩增,确定其阳性感染率,PCR阳性产物经测序并将结果与GenBank中的贾第虫序列比对,判断其分型。结果发现,616份样品中,有48份样品检验结果为贾第虫感染阳性,阳性率为7.79%(48/616)。不同地区感染率分别是:中国广州4.81%、越南胡志明市6.90%、马来西亚吉隆坡9.09%、新加坡2.86%和菲律宾马尼拉11.52%。其中48份样品在TPI和BG位点分别检测到条带,阳性率分别为7.63%和5.19%。阳性样品再经过对于BG及TPI基因位点的测序比对,得知BG位点有集聚体B型(3.33%)、集聚体C型(86.67%)、集聚体D型(10%),TPI位点有集聚体B型(2.12%)、集聚体C型(85.1%)和集聚体D型(12.76%)。综上,中国南海周边地区存在贾第虫感染,公共卫生相对较好地区感染率较低,犬源贾第虫基因分型分布未明显受到海洋地域隔离影响。

Investigation and genotyping of Giardia duodenalis infection in South China Sea

Giardia duodenalis, a parasitic intestinal parasite that is zoonotic, was spread all over the world. Moreover, its infection rate had a great relationship with the region and the environment. To understand the infection situation of canine duodenal Giardia duodenalis in the neighboring countries and regions of the South China Sea, and determine whether marine isolation is an important factor affecting Giardia duodenalis transmission.From June 2018 to July 2019, 616 canine fecal samples were collected from Guangzhou, China, Ho Chi Minh City, Vietnam, Kuala Lumpur, Malaysia, Singapore, and Manila, Philippines. DNA of canine fecal samples from each region were extracted, and a nested PCR was prepared by using the TPI gene and BG gene of Giardia duodenalis. The extracted canine fecal genomic DNA was used as a template for nested PCR amplification to determine its positive infection rate. PCR-positive products were sequenced and the results were compared with Giardia duodenalis sequences in GenBank to determine their typing.Among the 616 samples, tested results of 48 samples were positive for Giardia duodenalis infection, with a positive rate of 7.79% (48/616). The infection rates in different regions were 4.81% in Guangzhou, China, 6.90% in Ho Chi Minh City, Vietnam, 9.09% in Kuala Lumpur, Malaysia, 2.86% in Singapore, and 11.52% in Manila, Philippines. Among them, 48 samples were detected at TPI and BG sites, and the positive rates were 7.63% and 5.19%, respectively. The positive samples were then sequenced and compared for the BG and TPI gene sites, and it was learned that the BG site had conglomerate B type (3.33%), conglomerate C type (86.67%), and conglomerate D type (10%). TPI site had conglomerate B type (2.12%), conglomerate C type (85.1%), and conglomerate D type (12.76%). After statistical analysis and comparison, the difference between Giardia duodenalis genotypes in various regions was not significant. Giardia duodenalis infection existed in the surrounding areas of the South China Sea, and the infection rate was relatively low in areas with relatively good public health. The genotyping distribution of canine Giardia duodenaliswas not significantly affected by the isolation of marine areas.