[13] Genetic variability of Echinococcus granulosus based on the mitochondrial 16S ribosomal RNA gene

AbstractEchinococcusgranulosusis the etiological agent of cystic echinococcosis, a major zoonotic disease of both humans and animals. In this study, we assessedgeneticvariabilityandgeneticstructure ofE.granulosusin the Tibet plateau, using the completemitochondrial16 SribosomalRNAgenefor the first time. We collected and sequenced 62 isolates ofE.granulosusfrom 3 populations in the Tibet plateau. A BLAST analysis indicated that 61 isolates belonged toE.granulosussensu stricto (genotypes G1-G3), while one isolate belonged toE. canadensis(genotype G6). We detected 16 haplotypes with a haplotype network revealing a star-like expansion, with the most common haplotype occupying the center of the network. Haplotype diversity and nucleotide diversity were low, while negative values were observed for Tajima's D and Fu's Fs. AMOVA results and Fst values revealed that the three geographic populations were not genetically differentiated. Our results suggest that a population bottleneck or population expansion has occurred in the past, and that this explains the lowgeneticvariabilityofE.granulosusin the Tibet Plateau.