Effects of genital tract inflammation on human immunodeficiency virus type 1 V3 populations in blood and semen

Abstract

We have examined cell-free viral populations in the blood plasma and seminal plasma compartments of men infected with subtype C human immunodeficiency virus type 1 (HIV-1) using the V3-specific heteroduplex tracking assay (V3-HTA). We studied two cohorts of subjects who had visited either a sexually transmitted disease (STD) clinic for genital tract inflammation in the form of urethritis (n = 43) or a dermatology clinic (controls, n = 14) in Malawi. We have previously shown that the presence of urethritis is associated with an eightfold increase in virus load in the seminal plasma compartment (M. S. Cohen et al., Lancet 349:1868-1873, 1997). The purpose of this study was to determine whether genital tract inflammation and its treatment caused genetic instability in cell-free HIV-1 populations. In a cross-sectional analysis at study entry, three-fourths of the STD and control subjects had multiple V3 populations in their blood while 60% of the STD subjects and 79% of the control subjects had multiple V3 populations in their semen. Overall, one-fourth of all of the subjects showed discordance between results with blood and semen specimens when samples were compared for the presence and absence of subpopulations. When differences in the relative levels of abundance of bands were also taken into account, two-fifths of all of the subjects showed discordance between the compartments. Among the subset of subjects in whom multiple virus populations could be detected, half showed discordance between the compartments. There were no differences between STD and control cohorts for these comparisons of the compartments in this cross-sectional analysis at study entry. Longitudinal analysis of the viral populations from two separate clinic visits over 1 to 4 weeks showed that the complexity of each V3 population as measured by Shannon entropy was different in blood and semen at the two time points, indicating that the blood and semen constitute different compartments for HIV-1. The seminal plasma compartment was more dynamic than the blood plasma compartment for the STD subjects who were treated for urethritis, with changes being noted in the presence or absence of V3-HTA bands in the semen of 29% of these subjects but in the blood of only 9% of these subjects. However, the changes were generally small. Overall, our results suggest that 40% of male subjects show discordance between seminal and blood viral populations and that the complexity of each V3 population was different between the two compartments. Both of these results point to the partial independence of the seminal compartment as a viral niche within the body.

FIG. 1

(A) Comparison of the probes used for V3-HTA. The subtype C probe was cloned from subject C128 as described previously (20), while the subtype B probe was derived from the JR-FL molecular clone (15). (B) Examples of V3-HTA patterns for two subjects that showed different numbers of bands with the subtype C and subtype B probes. Only the bottom portions of the gels are shown. The arrow indicates the position of the probe homoduplex. Lanes are labeled by sample type at the first visit (blood [1B] or semen [1S]).

FIG. 2

Examples of the V3-HTA patterns of subjects with the same bands in blood and semen (A), subjects with different bands in blood and semen (B), and subjects with different relative levels of abundance of the same bands in blood and semen (C). The lanes are labeled as in Fig. 1, and the arrow indicates the position of the probe homoduplex. The V3-HTA patterns with the subtype C probe are shown for subjects S099 and C034; the V3-HTA patterns with the subtype B probe are shown for the other four subjects.

FIG. 3

Examples of V3-HTA patterns for subjects from whom specimens were collected at two time points for each compartment. Lanes are labeled by visit number (1 or 2) as well as sample type (blood [B] or semen [S]). The subtype C probe was used for subject S094, and the subtype B probe was used for subjects S029 and S036. The arrow indicates the position of the probe homoduplex.