Evaluation of a new dot blot assay for confirmation of human immunodeficiency virus type 1 and 2 infections using recombinant p24, gp41, gp120 and gp36 antigens

OBJECTIVE: A sensitive and accurate dot blot assay using recombinant p24 (gag), gp41 and gp120 (env) proteins of HIV-1 and also recombinant gp36, the specific HIV-2 antigen was developed to confirm the presence of antibodies in sera reactive in screening enzyme-linked immunosorbent assays.

METHODS: We collected sera from Iranian 125 confirmed HIV positive Iranian samples (seropositive group) from AIDS patients, asymptomatic HIV-infected subjects, HIV-infected intravenous drug users and also hemophilic infected subjects. The samples were obtained from the AIDS Specimen Bank, Pasture Institute, Iran during 2002 to 2003. We also obtained 180 samples (seronegative group) from healthy blood donors. Recombinant antigens were expressed in Escherichia coli. By use of highly purified antigens, the dot blot procedure was developed. Analysis of the results was accomplished by capturing the dot blot images.

RESULTS: We established and interpreted the results using Centers for Disease Control criteria. We defined the positive test result as the presence of antibody against at least 2 different HIV gene products, one of which had to be an env gene product while a negative test result was defined as no antibodies against any of the HIV gene products and an indeterminate result was defined as antibodies reacting with only one HIV env gene product or against gag gene product only.

CONCLUSION: The recombinant HIV dot blotting assay identified seropositive individuals with a high degree of accuracy; none of the HIV-seropositive subjects had a negative test result. Reactivity with these antigens, demonstrated 100% sensitivity and specificity in distinguishing seronegative from seropositive sera. The different sets of Western blot interpretative accepted criteria did not make a difference in interpretation of the seronegative and seropositive samples.