Variable relationship between proviral DNA load and infectious virus titre in the peripheral blood mononuclear cells of HIV-1-infected individuals

Abstract

Objectives To determine the relationship between infectious virus titre and proviral copy number in peripheral blood mononuclear cells (PBMC) of infected subjects and to ascertain which, if either, is most closely related to CD4+ cell loss and disease progression. Design and methods Cellular HIV-1 viraemia was quantified in 45 infected subjects who had not received antiretroviral therapy using limiting dilution tissue culture infective dose (PBMC TCID) and quantitative polymerase chain reaction (PCR) techniques. Results Proviral DNA was detected in 44 (98%) and infectious virus in 38 (82%) of the 45 subjects. Viraemia as measured by both culture and PCR was inversely correlated with patient CD4 + cell count and associated with disease status. Measurement using both techniques correlated with each other (Spearman's rank correlation rho = 0.52; P = 0.0006). The ratio of proviral copies to PBMC TCID ranged from 1:1 to > 1000:1. Conclusions The ratio of provirus:PBMC TCID was highest when the PBMC TCID was low, and approached unity when PBMC TCID was high. This ratio could be influenced by a variety of factors but did not correlate significantly with patient disease status or CD4+ cell count.