广东省部分地区卫氏并殖吸虫分布与DNA序列分析

Geographic distribution and gene sequencing of Paragonimus westermani in some areas of Guangdong Province

目的调查广东省卫氏并殖吸虫分布现状。方法解剖采集自广东省从化市良口、龙门县南昆山、乐昌市大洞和平远县木溪与郭屋等5个调查点山溪的螺蛳及溪蟹,检查卫氏并殖吸虫尾蚴、囊蚴。以所获囊蚴人工感染家猫、犬,解剖查找并殖吸虫成虫。取成虫样本,进行线粒体细胞色素C氧化酶亚单位I基因(COI基因)和核糖体基因第二间隔区(ITS2基因)基因序列分析,并与GenBank中现存并殖吸虫的COI、ITS2基因序列进行比对。结果良口、南昆山、大洞、木溪和郭屋5处疫源地的第一中间宿主螺蛳鉴定均为放逸短沟蜷,其尾蚴感染率分别为0.33%、0.15%、0.058%、0.10%和0.05%;第二中间宿主溪蟹鉴定均为平和华溪蟹,其囊蚴感染率分别为100%、100%、38.09%、55.36%和65.26%。良口、南昆山、大洞、木溪和郭屋平均每只蟹检出囊蚴数量分别为79.4、105.66、9.16、16.18个和15.6个,平均每克蟹含囊蚴数量分别为11.12、7.87、0.58、0.69个及0.85个,囊蚴鉴定均为卫氏并殖吸虫。人工感染家猫、犬体内检获卫氏并殖吸虫成虫与虫卵。良口、南昆山、大洞、木溪和郭屋5处调查点卫氏并殖吸虫成虫样本COI基因序列与GenBank中的AF219379.21、AF540958.1号基因序列同源性分别为99%、99%、99%、98%、99%,ITS2基因序列与DQ836243.1、DQ351845.1、AB354217.1号同种基因同源性分别为98%、99%、98%、98%、98%。结论广东省新发现2处卫氏并殖吸虫超高度疫源地和3处卫氏并殖吸虫高度疫源地,5地虫种间无明显差异。

Objective To investigate the current distribution of Paragonimus westermani in Guangdong Province. Method Snails and crabs collected from mountain streams in regional survey sites were dissected to detect cercarial and metacercarial infec tions of P. westermani. Domestic cats and dogs artificially infected with the collected metacercariae were also dissected to detect adult worms of P. westermani. The COI and ITS2 gene sequences of those adult worms were compared with those of known Paragon imus specimen deposited in the GenBank. Results All of the first intermediate hosts in five survey sites of Liangkou,Nankun, Mountain,Dadong,Muxi,Guowu,were identified as Semisulcospira libertina,whose cercariae infection rates were 0.33%, 0.15%,0.058%,0.10%,and 0.05%,respectively;the second intermediate hosts in above five sites were all identified as Sino potamon denticulatum,whose metacercariae infection rates were 100%,100%,38.09%,55.36%,and 65.26%,respectively. The numbers of metacercariae in the five sites were 79.4,105.66,9.16,16.18,and 15.6 per positive crab,respectively,and 11.12,7.87,0.58,0.69,and 0.85 per gram of crab,respectively. All the metacercariae were identical to those of P. westermani. Adult worms and eggs of P. westermani were found in both reservoir hosts of domestic cats and dogs infected artificially. By comparing the COI genes of five representative samples from each survey site with that of Paragonimus #AF219379.21,AF540958.1 from GenBank,we found out the homology to be 99%,99%,99%,98%,and 99%,respectively. In addition,a comparison of the ITS2 gene sequences between the above five samples and Paragonimus #DQ836243.1,DQ351845.1,AB354217.1 from Gen Bank revealed 98%,99%,98%,98%,and 98% gene homology,respectively. Conclusion Two ultra-high and three high en demic areas of P. westermani are discovered in Guangdong Province. No obvious differences were found among the types of P. wes termani in the above five endemic areas.