A cDNA encoding the highly immunodominant antigen of Strongyloides stercoralis: gamma-subunit of isocitrate dehydrogenase (NAD+)

A full length cDNA encoding the highly immunodominant 41 kDa antigen of Str ongyloides stercoralis (P5), recognized by 83% of human patients [Siddiqui et al. (1997) Parasitol Res 83:655-658], is obtained. A clone containing a 1371 bp insert was selected following screening of the S. stercoralis cDNA library with antibodies specific to antigen P5. The nucleotide sequence of this insert identified a cDNA coding for the gamma-subunit of isocitrate de hydrogenase (NAD(+)), GenBank Accession Number AF176568. The conceptually t ranslated amino acid sequence of the open reading frame for the gamma-subun it of S. stercoralis isocitrate dehydrogenase (NAD(+)) encodes a 388 amino acid residue protein with an apparent molecular weight of 43 kDa and a pred icted pI of 7.15. The sequence is 71% A/T, reflecting the characteristic A/ T codon bias of S. stercoralis. The amino acid sequence of the S. stercoral is gamma-subunit of isocitrate dehydrogenase (NAD(+)) is compared with thos e of Caenorhabditis elegans, rat and human NAD(+)-ICDH. The diagnostic pote ntial of the S. stercoralis gamma-subunit of isocitrate dehydrogenase (NAD( +)) is also discussed.