Characteristics of genetic differentiation of Echinococcus multilocularis and E.shiquicus in Qinghai region
Objective To analyze the genetic differentiation characteristics of Echinococcus multilocularis and E.shiquicus in Qinghai region to provide theoretical support for the prevention and control of echinococcosis in Qing-hai Province.Methods Small mammals were captured in the main natural endemic areas of Echinococcus spp.in Yushu,Guoluo,and Huangnan Tibetan Autonomous Prefecture and were dissected to collect cysts.The genomic DNA from cysts tissue was extracted and the cytochrome oxidase 1(cox1)gene was amplified using PCR and sequenced.DnaSP v6,Iqtree,BEAST v2.7.4 and other software were used for haplotype analysis,nucleotide polymorphism analy-sis,construction of a phylogenetic tree,and estimation of the divergence time of the Echinococcus genus.Results A total of 55 hydatid cysts were obtained from 2 864 small mammals.All 55 cyst samples were amplified for coxl bands with a length of approximately 800 bp,of which 37 were E.multilocularis,and 18 were E.shiquicus,the preva-lence of E.multilocularis in Neodon fuscus was 1.96％(37/1884).The prevalence of E.shiquicus in Ochotona curzoniae was 1.84％(18/980).In the 37 coxl sequences of E.multilocularis,there were 5 haplotypes in the 37 coxl sequences of E.multilocularis with EmH3 being the predominant one(33/37),the haplotype diversity index was 0.207,the nucleo-tide diversity index was 0.033 55,and there were 156 variable sites.In the 18 coxl sequences of E.shiquicus,There were 8 haplotypes,with the EsH2 haplotype being the predominant one(8/18),the haplotype diversity index was 0.778,the nucleotide diversity index was 0.060 52,and there were 14 variable sites.Thirteen haplotypes of E.multilocularis and E.shiquensis were uploaded to GenBank.The accession numbers of haplotypes EmHl-EmH5 are OR821706,OR821707,OR830343,OR830344,OR826123,respectively.The accession numbers of haplotypes ESH1-ESH8 are OR835156,OR835157,OR830376,OR830378,OR831110,OR875250,OR835161,OR841080.The phylogenetic tree shows that the 5 haplotypes of E.multilocularis were clustered together with the Asian strain of E.multilocularis,and the 8 haplotypes of E.shiquicus were clustered with E.shiquicus in the GenBank.The divergence time based on the coxl gene showed that the common ancestor of E.granulosus,E.multilocularis,E.shiquicus,E.oligarthrus and E.vo-geli existed approximately 5.67 million years ago(Mya)(95％CI:4.72-6.66 Mya),and the average divergence time for E.granulosus,E.shiquicus and E.multilocularis was approximately 2.02 Mya(95％CI:1.51-2.49 Mya).Conclusion E.multilocularis and E.shiquicus in Qinghai region have high genetic diversity,with EmH3 haplotype dominating E.multilocularis and EsH2 haplotype dominating E.shiquicus.
Echinococcus multilocularisEchinococcus shiquicusHaplotypecox1 genePhylogenetic analysisDivergence time
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