QUANTIFICATION OF LOW-LEVELS OF HUMAN-IMMUNODEFICIENCY-VIRUS (HIV) TYPE-1 RNA IN P24 ANTIGEN-NEGATIVE, ASYMPTOMATIC, HIV-POSITIVE PATIENTS BY PCR

A nested PCR was used to quantify small numbers of human immunodeficie ncy virus (HIV) type 1 (HIV-1) RNA particles in the serum specimens of 26 p24 antigen-negative, asymptomatic, HIV-positive patients undergoi ng antiretroviral therapy. Fifteen patients received zidovudine (ZDV) and alpha interferon, and 11 patients received ZDV monotherapy. After PCR, the amounts of RNA were quantified by comparing the endpoint dilu tions of serum samples with a standard curve with known amounts of vir al particles. Before the beginning of the antiviral therapy, HIV-1 RNA was detected in 92% of the patients. After treatment, a fall in the n umber of viral particles was detected in patients receiving combinatio n therapy (mean titers +/- standard errors of the means, 3,617 +/- 756 pretherapy versus 1,800 +/- 845 posttherapy; P < 0.05) and in patient s receiving monotherapy (3,763 +/- 642 pretherapy versus 1,353 +/- 394 posttherapy; P < 0.05). Our results indicate that PCR with nested pri mers may be useful for assessing the changes in viremia in HIV-positiv e patients with low viral load undergoing antiviral therapy.