Comparative Genotyping of Echinococcus granulosus Infecting Livestock in Turkey and Iran

Echinococcus granulosus contains a complex of different strains that represent diversity in the pattern of the life cycle and also their host types. So far 10 genotypes of this parasite have been identified, using molecular methods. The current study aimed to evaluate and compare the genotypic diversity of E. granulosus metacestodes from livestock of Turkey and Iran.

A total of 90 livestock liver and lung organs infected with hydatid cyst from industrial slaughterhouses of Bonab Province in the East Azerbaijan Province in Iran (60 samples, including 30 sheep and 30 cattle) and Van Province in Turkey (30 samples, including 15 sheep and 15 cattle) were collected. DNA was extracted from the protoscolices or germinal layers and polymerase chain reaction (PCR) were utilized, targeting the partial mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase 1 (nad1) genes. PCR products were isolated from the electrophoresis gels and sequenced. The sequences were compared with each other, as well as with those related available sequences in the GenBank, using the BioEdit software and the BLAST algorithm. Finally, the phylogenetic trees were constructed by comparing sequences of cox1 and nad1 fragments, using the MEGA7 software and the maximum likelihood method.

All samples sequenced from Iran corresponded to the genotype G1 (100%). Among the samples from Turkey, 15 samples (78.9%) were identified as G1 while only one sample (5.3%) corresponded to the genotype G3 and 3 isolates (15.8%) were defined as genotypes G1/G3. Five distinct haplotypes were determined within the examined isolates from sheep and cattle in both countries and all isolates clustered in one group. Phylogenetic analysis revealed that the intra-species genetic variations were 0.0-0.6% and 0.0-1.4% for cox1 and nad1, respectively.

The dominant genotype of E. granulosus sensu stricto of livestock in both countries was the G1 (sheep strain) genotype. Our findings indicate that the sheep-dog cycle is the leading cycle of E. granulosus in these two areas. Hence, adopting regional common policies and bilateral cooperation helps to control the disease in livestock as well as in human in these two regions. Further study is required to compare the genetic diversity of human isolates of E. granulosus in these two countries.