BACKGROUND: HIV-infected individuals, women more than men, are more likely to report unprotected sexual behaviour with an HIV positive partner than with an HIV negative partner. Cases of superinfection after the initial HIV infection have been recently published. Here, we studied the pattern of HIV-RNA level progression over time among HIV-infected patients who have repeated sexual exposure to HIV.   

METHODS: The analysis was performed among non-intravenous drug users HIV-infected women enrolled from 1988 to 1996 in the SEROCO ANRS cohort or since 1996 in the PRIMO ANRS cohort. In both cohorts, the same questionnaire was used to collect at each 6-month visit information on sexual partners and condom use since the last visit. Women with available data on their sexual practices while not receiving antiretroviral therapy were selected. Women who reported at least once inconsistent condom use with an HIV positive or of unknown status partner (sexual risk behaviour SRB) were considered at risk for HIV superinfection.

RESULTS: Among the 120 heterosexual women considered in this analysis, 59 reported at least once a SRB over the study period. They tended to have higher baseline CD4+ cell count when compared to the other 61 women (median: 756 versus 641, p= 0.07), but had similar baseline VL. Among the 51 women with baseline viral load (VL) < 4 log copies/ml, the occurrence of SRB (included as a time-dependent covariate in a Cox model) tended to be associated with a more rapid progression to VL > 4 log copies/ml (RR=2.31 (95% CI: 0.96-5.52), p=0.06, adjusted for baseline CD4+ count, age at HIV infection, and symptomatic primary infection). When modelling the progression of HIV-RNA level over time since HIV infection (using a mixed effect model), the occurrence of a SRB (as a time-dependent variable) resulted in an increase in the average rate of HIV-RNA progression (mean increase after SBR, compared with no SBR = +0.01 log copies/ml per month, p=0.02), among women with baseline VL < 4 log copies/ml. Among women with baseline VL > 4 log copies/ml SBR was not related to the rate of HIV-RNA progression.

CONCLUSION: Women with a baseline VL < 4 log copies/ml who reported unprotected sex with an HIV positive or HIV unknown status partner tended to more rapidly increase their HIV-RNA level than other women who did not report such sexual behaviour. Those results are compatible with HIV superinfections, which are currently under investigation.