A microELISA system for the detection of both anti-HIV-1 and anti-HIV-2 antibodies

Chimeric synthetic peptide as antigen for immunodiagnosis of HIV-1 infection

One chimeric peptide incorporating antigenic sequences from the gp41 transmembrane region (peptide H-18) and the gp120 envelope region (peptide H-15) corresponding to amino acids (587-617) on gp41 and (495-516) on gp120 of human immunodeficiency virus (HIV 1) was synthesized. Both sequences were separated by two glycine residues. This peptide was evaluated as antigen in an ultramicro-enzyme-linked immunosorbent assay (UMELISA) with samples derived from HIV-1 (n = 30) with different titers of antibodies and healthy blood donors (n = 30). The results were compared to plates coated with monomeric peptides and to plates coated with two monomeric peptides together. Results demonstrated that monomeric peptides gp41 (H-18) and gp120 (H-15) were good as antigens with samples that present antibodies to these regions. The chimeric peptide was the most antigenic. Those results may be related to the peptide structure, adsorption to the solid surface, and epitope accessibility to the antibodies. This chimeric peptide would be very useful for HIV-1 diagnostics.

Performance characteristics of recombinant enzyme immunoassay to detect antibodies to human immunodeficiency virus type 1 (HIV-1) and HIV-2 and to measure early antibody responses in seroconverting patients

We investigated the performance of a double-antigen sandwich recombinant enzyme immunoassay (EIA; Abbott Laboratories, North Chicago, Ill.) and compared it with that of a synthetic-peptide-based EIA (Biochem Immunosystems, Montreal, Quebec, Canada) for the detection of human immunodeficiency type 1 (HIV-1) and HIV-2 antibodies in 2,321 clinical serum samples. The results of both EIA methods and Western blot (immunoblot) were in agreement for 1,046 HIV-1 and 10 HIV-2 specimens from a panel of known positives. From a prospective panel of 1,085 specimens, 38 proved to be positive by both EIAs and Western blot, 3 were positive by the recombinant EIA only, and 9 were positive by the peptide EIA only, for calculated specificities of 99.71 and 99.04%, respectively. Of 180 specimens from a seroconversion panel collected from 77 patients, the results for 170 were in agreement by all antibody testing methods and 10 were found to be repeat reactive for HIV antibodies by the recombinant EIA only. All 10 were initial specimens of seroconverting patients; 7 were also reactive for HIV p24 antigen. An examination of four of these sera by radioimmunoprecipitation assay showed gp120 and gp160 bands in each. Analysis of the anti-Env antibody class in three of these samples showed that one consisted of immunoglobulin M (IgM) only and two contained both IgG and IgM antibodies. Although both EIA procedures were sensitive and specific in the detection of antibodies to HIV-1 and HIV-2 and both were capable of detecting early antibodies, the recombinant assay was more sensitive for antibody detection during early seroconversion.

Two-colour combination enzyme-linked immunosorbent assay for the simultaneous detection of HBV and HIV infection

To reduce the cost, time and waste in screening for HIV and HBV infections a combined assay for HIV-1 and -2 antibodies and HBsAg has been developed. Monoclonal anti-HBs antibodies were co-immobilized with synthetic peptides representing immunodominant regions of HIV-1 and -2. The presence of anti-HIV antibodies in the samples was detected with alkaline phosphatase-labelled anti-human IgG and of HBsAg with horseradish peroxidase-labelled monoclonal anti-HBs antibodies by a sequential substrate reaction. In this assay, HBsAg was detectable in a concentration range between 0.25 and 0.30 U/ml and the results were available within 3 h. The specificity, tested on 5000 serum samples from blood donors after confirmation, was 99.8% for HBsAg and 99.5% for anti-HIV antibody detection. All serum samples taken from 600 HIV-1- and 115 HIV-2-infected individuals were correctly classified as reactive. The two-colour HBsAg-anti-HIV-1/-2 combination ELISA meets all the requirements of single parameter assays with regard to precision, stability and robustness.