湖南娄底市犬弓首蛔虫流行状况及线粒体cox 1和nad 4序列变异分析

Toxocara canis Prevalence and Genetic Variation of Mitochondrial cox 1 and nad 4 Sequences in Loudi City,Hunan Province

为了解湖南省娄底市犬弓首蛔虫流行状况及虫株遗传变异情况,本试验于2021年3—9月对该地区368份犬粪便和104份环境(土壤和水源)样品的犬弓首蛔虫污染情况进行调查;对9个犬弓首蛔虫分离株线粒体cox 1和nad 4序列进行扩增、测序与分析。结果显示:被调查的犬粪便和环境样品的犬弓首蛔虫虫卵检出率分别为13.59%(50/368)和18.27%(19/104);其中宠物犬(11.74%)较流浪犬(17.36%)来源粪便样品检出率低,公园来源土壤样品(9.09%)较小区来源样品(3.92%)检出率高;9个犬弓首蛔虫分离株线粒体cox 1和nad 4序列长度分别为424 bp和1197 bp,核苷酸序列同源性为99.4%~100.0%和98.7%~100.0%,与其他具有代表性蛔虫分离株对应序列同源性均低于90%;9个犬弓首蛔虫分离株线粒体cox 1和nad 4序列核苷酸多样性分别为0.007±0.002和0.006±0.003。结果表明湖南娄底市犬弓首蛔虫分离株遗传变异较低,但虫卵流行状况严重,且存在于公共环境中,对人类健康造成潜在威胁。

This study investigated the prevalence of Toxocara canis infection in dogs,the existence of T.canis eggs in public environment,and analyzed the genetic variation of T.canis in Loudi city,Hunan province.A total of 368 feces from dogs and 104 environmental(soil and water)samples were collected between March and September 2021 and examined for the presence of T.canis,and the mitochondrial cox 1 and nad 4 sequences from 9 T.canis isolates were amplified and analyzed.The results showed that the detection rates of T.canis eggs in dog feces and environmental samples were 13.59%(50/368)and 18.27%(19/104),respectively;the prevalence rate of T.canis eggs in pet dogs(11.74%)was lower than that of stray dogs(17.36%);the detection rate of T.canis eggs in soil samples in the park(9.09%)was higher than that in the community(3.92%);the mitochondrial cox 1 and nad 4 sequences of 9 T.canis isolates were 424 bp and 1197 bp in length,respectively;the nucleotide sequence homology were 99.4%-100.0%and 98.7%-100.0%,respectively,both of the cox 1 and nad 4 genes of 9 T.canis isolates displayed<90%sequence homology with those of representative Ascaris canis isolates from GenBank database;the nucleotide diversities of cox 1 and nad 4 sequences of 9 T.canis isolates were 0.007±0.002 and 0.006±0.003,respectively.Thus,T.canis isolates from Loudi city,Hunan province,display low genetic variation,but T.canis eggs have a common presence in the public environment,and thus pose a potential threat to human health.