A first insight into the genotypes of Echinococcus granulosus from humans in Mongolia

Abstract

Polymerase chain reaction (PCR)-based single-strand conformation polymorphism (SSCP) and targeted sequencing were employed to genetically classify Echinococcus granulosus cysts from humans from 12 provinces in Mongolia using two DNA loci, designated pcox-1 and pnad-1, within the mitochondrial cytochrome c oxidase subunit 1 (cox-1) and NADH dehydrogenase subunit 1 (nad-1) genes, respectively. SSCP analysis of pcox-1 and pnad-1 amplicons produced from genomic DNA samples from individual E. granulosus cysts (n = 50) from individual humans displayed four distinct electrophoretic profiles for each pcox-1 and pnad-1. The direct sequencing of selected amplicons representing each of these profiles defined four distinct sequence types for each locus, present in four different combinations (designated as haplotypes M1-M4) for all 50 cyst isolates. Phylogenetic analysis of concatenated sequence data for these four haplotypes, including well-defined reference sequences, inferred that 68% of the cyst isolates belonged to the G1-G3 complex of E. granulosus (or E. granulosus sensu stricto), whereas the remaining (32%) were linked to the G6-G10 complex (or Echinococcus canadensis). Humans infected with E. granulosus cysts of the G1-G3 complex originated mainly from the eastern regions of Mongolia, whereas those harbouring cysts of the G6-G10 complex were from the western part of this country. The present study provides a first glimpse of the genetic composition of E. granulosus from humans in Mongolia, and forms a foundation for future studies of the epidemiology and ecology of the parasite(s) in animals and humans in this and surrounding countries.