Genetic Variation in Mitochondrial COX1 and Ribosomal ITS2 Genes of Toxocara Canis in Stray Dogs in Zabol, Southeast Iran

Toxocariasis is a zoonotic parasitic disease with worldwide distribution caused by the larval stage of ascaridoid nematodes of dogs (Toxocara canis) and cats (Toxocara cati). The study was accomplished to determine the sequence variation in ITS2 and COX1 genes within isolates of Toxocara canis.

Two hundred Stool samples were collected randomly from dogs in public parks and streets from different regions of Zabol. Thirty samples containing eggs were isolated from the feces using Formalin ether 10% and centrifugal flotation. Genomic DNA was extracted, and COX1 and ITS2 were amplified by PCR-RFLP and sequenced. Sequence data were aligned using the BioEdit software and BLAST program and compared with published sequences in GenBank. The phylogenetic relationship between isolates of T. canis from Zabol city with other regions based on sequences obtained from COX1 and ITS2 genes and using MEGA7.0 software was investigated.

For all samples, amplicons of about 388 and 422 base pairs were produced by PCR for ITS2 and COX1, respectively. Drawing the phylogenic tree of ITS2 and COX1 sequences of isolates of T. canis  showed that the identified genotypes are not only different from each other but also from other parts of the world.

Our result showed that genetic variation among isolates of T. canis from Zabol is very low. For a deeper understanding of genetic diversity among populations of Toxocara, it is recommended to analyze more isolates from various geographical areas and variable genetic markers.