Designing of novel antigenic peptide cocktail for the detection of antibodies to HIV-1/2 by ELISA

HIV (human immunodeficiency virus) infection has now become endemic worldwide and AIDS ranks fourth among the world's top killers of mankind. A rapid and accurate HIV testing assay is a pre-requisite for practical applicability of diagnostic tests. The aim of this present study was to design peptide cocktail as an antigen and to develop ELISA test for HIV-1/2 antibody detection, with enhanced sensitivity and specificity. A novel peptide stretch V3-I, covering immunodominant epitope corresponding to V3 hypervariable loop of gp120 antigens of selected Indian isolates, has been studied and incorporated in an antigenic cocktail of gp36, gp41, and rp24 of HIV-1/2. Peptides from these antigens were chemically synthesized and an additional cysteine residue was added at both amino- and carboxyl-terminal sequences of each peptide in order to form inter and intramolecular disulfide bond for the folding of peptides. This generated conformational epitopes with increased oligomericity and stability of peptide sequences; and attachment of antigen to the solid support of ELISA plates. The use of antigenic cocktail of folded peptides and recombinant p24 enhanced sensitivity and specificity of the ELISA test. Evaluation of the test using 1123 serum samples in comparison with Boston Biomedical Incorporation (BBI) panels showed 100% sensitivity and 99.3% specificity with no cross reactivity tribulation. In conclusion, “HIV screen test” detects HIV 1/2 antibodies with a high degree of sensitivity and specificity and could be a promising tool for seroscreening of blood during transfusion, counseling and diagnosis of HIV-1/2.