Sequencing and phylogenetic analysis of mitochondrial cox1 and nad1 genes in Toxocara canis and Toxascaris leonina isolates from Iran

Abstract

Toxocara canis and Toxascaris leonina are the most important ascaridoid nematodes of the family Toxocaridae. The present study was aimed to characterisation and analysis of genetic variation within and among T. canis and T. leonina isolates obtained from Iran by sequencing partial mitochondrial cytochrome c oxidase subunit 1 (pcox1) and partial NADH dehydrogenase subunit 1 (pnad1) genes. A total number of 134 adult nematodes belonging to Toxocaridae family were collected from stray dogs in Alborz province, Iran during 2015 and 2016. Polymerase chain reaction (PCR) was performed and products were sequenced. Sequences of two mitochondrial cox1 and nad1 genes were compared with other sequences in the GenBank, while multiple sequences alignment analysis was performed using the Bioedit and MEGA6 software and phylogenetic tree was plotted. For all isolates, amplicons of about 450 and 350 base pairs (bp) were successfully produced by PCR for cox1 and nad1, respectively. All sequences of T. canis isolates from present study were 100% homologous across the nad1 gene but not in the cox1 gene. The results indicate that the PCR method based on sequence of cox1 and nad1 genes is a suitable technique for the differentiation of T. canis and T. leonina species and that mtDNA regions could be used as genetic markers for the identification and differentiation of Toxocara species.

Keywords

• cox1
• iran
• mtdna
• nad1
• toxocara canis
• toxascaris leonina