Molecular Cloning and Sequence Analysis of C Type Lectin (Tc-CTL-1) from Infective Larval Stage of Toxocara canis

Toxocara canis is an important nematode impacting the health of dogs and humans alike. The gene encoding the excretory-secretory antigen of Tc-CTL-1 from larvae of T. canis was cloned and the sequence was analyzed. Total RNA was isolated from T. canis infective larvae and reverse transcription was done with oligo dT primers to obtain complementary DNA (cDNA). Amplification by PCR was performed with cDNA as a template and specific primers of the gene of Tc-CTL-1, yielding an amplicon size of 603 bp. The amplicon was cloned into pTZ57R/T cloning vector and the clone was confirmed by colony PCR and restriction enzyme analysis. The sequence analysis of Tc-CTL-1 Tamil Nadu isolate revealed 99.6% similarity with the previously published sequences of Iran isolate (KU852582), 99.5 and 99.1% homology with the Japan isolate (AB009305) and UK isolate (AF041023), respectively. Phylogenetic relationship showed that the Tamil Nadu isolate of Tc-CTL-1 shared a common ancestor with the isolates of UK, Japan and Iran. Further expression studies are required for producing the recombinant protein for its evaluation in the diagnosis of T. canis infection in humans as well as in dogs.