Genetic Variation Among The Isolates Of Echinococcus Multilocularis From Western China

Objective: Alveolar echinococcosis(AE) is a life-threatening human disease caused by Echinococcus multilocularis transmitted between rodent hosts and dogs/foxes. The parasite distributes throughout the Northern Hemisphere with more than 30 species of rodents as intermediate hosts, which should cause large genetic variations.Method: In the present study, we identified three fragments of mitochondrial genes(Cob, Nad2 and Cox1) of the parasite collected from AE patients(n=44) and rodents in western China. Using PCR method to get the sequence, after the success of the sequencing, and through the Bio Edit, the comparison of multiple sequences, using Meg Align to calculate the genetic distance. MEGA6.0 software was used to cluster analysis of the obtained sequence, as well as the production of phylogenetic tree, through the production of NETWORK4.6.1.3 haploid network.Results: Relatively low genetic variation was found in those isolates. Sequences from rodents showed two haplotypes. The Cob sequences from AE patients showed two haplotypes, while Nad2 had 4 haplotypes. Combined with the sequences published in the Gen Bank database, we clustered 44, 41 and 62 sequences of Cob, Nad2 and Cox1 fragments respectively, which showed 5 genotypes including three Asian genotypes, one from Europe and one from Northern America.Conclusion: These haplotypes were distributed in both Qinghai and Xinjiang provinces. Most AE patients harbor the Asian genotype I which may be an indication of its relative frequency in definitive hosts and the environment or of its pathogenicity to humans, which calls for further research.