Characteristics and clinical significance of a stabilization assay to detect specific antibodies to reverse transcriptase of human immunodeficiency virus.

Antibodies against reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) have been detected in seropositive subjects by immunoprecipitation, Western immunoblotting, and neutralization assay. Recently, we noticed that the antibodies against RT stabilized RT upon heat inactivation, and we have developed a stabilization assay of RT antibody. Briefly, the RT of HIV-1 is completely inactivated by incubation at 56 degrees C for 20 min, but this inactivation is inhibited in the presence of a specific antibody directed against this molecule. We examined the specificity and clinical significance of this stabilization assay. HIV-1 antibody-positive sera stabilized HIV-1 RT but not HIV-2 RT, whereas half of these sera cross-neutralized HIV-2 RT. Antibody titers against RT determined by the neutralization assay and the stabilization assay were compared with clinical characteristics. Antibodies against HIV-1 RT were much more frequently detected by the stabilization assay than by the neutralization assay. Statistically significant associations were found between stabilizing antibody titer and CD4+ cell number in peripheral blood of patients and also between antibody titer and CD4+/CD8+ ratios. These results indicate that our new stabilization assay to detect specific antibodies against RT of HIV-1 is useful as a clinical marker of infection and progress of the disease.