Viral variants tend to exhibit significant sequence diversity in their envelope segment, making immunoassays solely dependent on epitopes from this region unreliable. Combining the p24 core antigen with a selected high-impact segment from the envelope would therefore make sense, and our solution is indeed patented technology:
This protein is a 258 amino acid fusion protein, supplied in frozen format and consisting of the Type 1 HIV p24 core polypeptide with a conserved, highly immunoreactive envelope polypeptide sequence derived from HIV-2 envelope inserted at the gene level. The protein has been designed with a similar strategy as that employed to develop the p24-env (Type 1) antigen described above, but now carries a specific, conserved structure from the HIV Type 2 transmembrane protein. The expressed hybrid molecule has been subjected to extensive purification produces a single band on SDS and is soluble in physiological buffer. The HIV Type 2 p24 env recombinant polypeptide contains no non-HIV related sequences. It has proven highly effective in detecting HIV Type 2 antibodies in sera from individuals infected with this virus. This protein requires judicious application of the purification protocol and is typically obtained in somewhat lower yield than its Type 1 counterpart.
(Purchase of the protein carries an implicit license for its use as a diagnostic source ingredient)