Cytochrome c oxidase subunit 1 and 12S ribosomal RNA characterization of Coenurus cerebralis from sheep in Iran.

Taenia multiceps is a widely distributed zoonotic tapeworm of canids. The larval stage of the parasite (Coenurus) occurs in sheep, goat and cattle and has been rarely reported from humans. This study investigated genetic variability of two mitochondrial genes in 102 isolates of T. multiceps. Metacestodes were collected from brains and hearts of sheep in Tehran and Qom provinces of Iran. DNA of each isolate was extracted and used for PCR amplification of cytochrome c oxidase subunit I (CO1) and 12S ribosomal DNA (12S rRNA) genes. All amplicons were sequenced and the sequence data were analyzed using NCBI Blast and BioEdit. Phylogenetic trees and pairwise calculations were obtained by using Mega5 software. In total 7 and 25 representative haplotypes were differentiated for CO1 and 12S rRNA genes, respectively. For CO1 sequences 11 segregation sites within 7 haplotypes were observed. For 12S rRNA sequences a total of 32 segregation sites were observed in 25 haplotypes. CO1 gene displayed lower diversity than 12S rRNA gene with an overall nucleotide variation of 3.0% for CO1 vs. 7.2% for 12S rRNA. Pairwise comparisons among 7 haplotypes in CO1 and 12S rRNA genes showed the level of nucleotide differences 0.3-2.5% and 0.2-4.0%, respectively. A high degree of genetic variation was found in the isolates of T. multiceps in Iran. Additional molecular studies are required on the parasite from other intermediate hosts.