Frequent Detection of HIV-1-Specific mRNAs in Infected Individuals Suggests Ongoing Active Viral Expression in All Stages of Disease

Abstract

It has been shown that only a small fraction of CD4⁺ T cells are infected with human immunodeficiency virus type 1 (HIV-1) in vivo, particularly early in the course of infection. An even smaller proportion of cells have been shown to be expressing virus. Recent studies suggest that plasma viremia in asymptomatic HIV-infected individuals, representing active viral replication, is more common than was previously believed (range 23–100% of patients). To determine the in vivo state of HIV expression, samples of peripheral blood of 49 HIV-infected individuals at all stages of disease were examined. All subjects were positive for viral DNA by standard polymerase chain reaction (PCR), and a modified PCR was utilized to detect HIV-specific mRNAs (gag, major splice junction, env, and tat/rev). Patient's plasma was also assayed for p24 antigen and viremia.

The results were as follows: Overall, the findings suggest that active viral expression occurs at all stages of HIV infection. In particular, the presence of gag mRNA was determined in only 2 of 14 patients with T4% > 30% but in 20 of 35 patients with T4% ≤ 30% (p < 0.05), demonstrating a direct association between the presence of message for a structural protein, and more advanced immunosuppression. Determination of the expression of certain HIV-specific messages from within a patient's cells adds a new dimension to understanding the pathogenesis of HIV infection. The presence of HIV-specific mRNAs, and in particular gag message, in many healthy seropositives may further argue for early initiation of antiviral therapy.