The diagnostic antigen encoded by gene fragment Dv3-14: a major sperm protein of Dictyocaulus viviparus.

The Dv3-14 gene fragment of Dictyocaulus viviparus is 471 bp, of which about 90% is translated. The calculated molecular mass of the translation product is 15.5 kDa. DNA sequence homologies were found with major sperm proteins (MSPs) from Ascaris suum, Caenorhabditis elegans and Onchocerca volvulus. Within a segment of 62 amino acids the predicted amino acid sequence of Dv3-14 shows 84% homology with an A. suum MSP and 84% homology with a C. elegans MSP. Computer analysis of the protein sequence identified three segments of immunodominant antigenic sites as putative candidates for synthetic peptide antigens. Immunoblotting analysis of the translated product showed that it is adult stage specific, water soluble and not membrane bound and can be demonstrated in the supernatant fluids of cultures from adult worms kept in cell culture medium. The results suggest that the protein encoded by Dv3-14 is a MSP of D. viviparus.