[Study on the molecular phylogeny of Echinococcus multilocularis in Qinghai Province].

OBJECTIVE

To amplify and sequence Coxl and Nadl genes in Echinococcus multilocularis isolates from Qinghai Province, and to create phylogenetic trees and molecular clocks, so as to provide evidence for estimating the evolutionary relationships and origins of E. multilocularis in Qinghai Province.

METHODS

Twenty-two post-surgical specimens of patients with hepatic alveolar echinococcosis were sampled from Qinghai Provincial People's Hospital in 2017. The Coxl and Nadl genes were amplified from E. multilocularis samples and sequenced. Then, the gene sequences were aligned to the Coxl and Nadl genes of Echinococcus species in GenBank database. The intra-species variation was observed, and the phylogenetic tree and molecular clock were created.

RESULTS

All E. multilocularis samples shared more than 99% genetic homology with the sequences of Coxl and Nadl genes from the E. multilocularis Asian strain in the GenBank database. A total of 6 genotypes were identified, including 2 isolates that had no 100% homology with the sequences of known genes in the GenBank database. Phylogenetic tree analysis revealed remarkable clustering of the E. multilocularis samples with the E. multilocularis Asian strain, and the E. multilocularis isolates from Qinghai Province were estimated to date back to 94 000 years ago by the molecular clock.

CONCLUSIONS

The present study characterizes 6 E. multilocularis genotypes in Qinghai Province, including 2 novel genotypes. Asian strain is the predominant strain of E. multilocularis in Qinghai Province, and the E. multilocularis isolates from Qinghai Province date back to 94 000 years ago.