Cloning and sequence analysis of <i>H. contortus<i> HC58cDNA gene

Abstract

The complete coding sequence of Hemonchus contortus HC58cDNA was generated by rapid amplification of cDNA ends and polymerase chain reaction using primers based on the 5\' and 3\' ends of the parasite mRNA, accession no. AF305964. The HC58cDNA gene was 851bp long, with open reading frame of 717bp, precursors to 239 amino acids coding for approximately 27kDa protein. Analysis of amino acid sequence revealed conserved residues of cysteine, histidine, asparagine, occluding loop pattern, hemoglobinase motif and glutamine of the oxyanion hole characteristic of cathepsin B like proteases (CBL). Comparison of the predicted amino acid sequences showed the protein shared 33.5% to 58.7% identity to cathepsin B homologues in the papain clan CA family (family C1). Phylogenetic analysis revealed close evolutionary proximity of the protein sequence to counterpart sequences in the cathepsin B like proteases, suggesting that HC58cDNA was a member of the papain family.

Keywords:Haemonchus contortus, HC58cDNA, cathepsin B like protease, papain family

Kenya Veterinarian Vol. 31 (2) 2007: pp. 45-53