Correlation of serum HIV antigen and antibody with clinical status in HIV-infected patients.

An enzyme immunoassay (EIA) has been developed which detects antigen(s) (Ag) of the human immunodeficiency virus (HIV) in the serum of patients with the acquired immunodeficiency syndrome (AIDS), AIDS-related complex (ARC), and patients at high risk for HIV infection. The test has a sensitivity of approximately 50 pg/ml of HIV protein. The specificity of the assay was determined with various virus infected cell lines, normal human sera/plasma, and serum from patients not known to be at risk for HIV infection. No false-positive HIV-Ag results were seen. Sera from 69% of patients with AIDS were positive for HIV-Ag as were 46% of patients with ARC and 19% of asymptomatic, HIV-antibody-positive individuals. There were significant associations between the stage of HIV infection--ie, AIDS vs ARC vs asymptomatic--and the detection of HIV-Ag in serum (p less than 0.0001) and the lack of detection of antibody to HIV core Ag (p less than 0.0001). HIV-Ag was also found in the serum of two asymptomatic antibody-negative individuals who were at high risk for AIDS and who later developed HIV antibody. The presence of HIV-Ag in sera was confirmed by an inhibition procedure. Thus, HIV-Ag can be detected in the serum of infected individuals prior to antibody production and correlates with the clinical stage of HIV infection.