Lack of protection against HIV-1 infection among women with HIV-2 infection

Objective: To assess whether HIV-2 infection protects against HIV-1 infecti on by comparing the rate of HIV-1 seroconversion among HIV-negative and HIV -2-seropositive women followed in a cohort study in Abidjan, Cote d'lvoire. Design: Prospective cohort study. Methods: HIV seroconversion was assessed in 266 HIV-seronegative, 129 HIV-1 -seropositive, and 127 HIV-2-seropositive women participating in a closed c ohort study of mother-to-child transmission of HIV conducted during 1990-19 94. Participants were seen every 6 months, and blood samples were obtained. AII blood samples were screened for HIV antibodies by enzyme immunoassay ( EIA) and confirmed by line Immunoassay (LIA) and Western blot. Among women who were HIV-seronegative at enrolment, seroconversion was defined as new E IA-reactivity confirmed on LIA and Western blot. Among HIV-1- or HIV-2-sero positive women, seroconversion to dual reactivity was defined as new dual r eactivity on the LIA that was confirmed by reactivity on both HIV-1- and HI V-2-monospecific EIA. Results: Five HIV-seronegative women became HIV-1-seropositive (seroconvers ion rate, 1.1 per 100 person-years; 95% confidence interval (CI), 0.3-2.5), and none became HIV-2-seropositive. No HIV-1-seropositive women became HIV -1/2 dually reactive, whereas six HIV-2-seropositive women acquired HIV-1 s eroreactivity ar-id thus became HIV-1/2 dually reactive (seroconversion rat e 2.9 per 100 person-years; 95% CI, 1.1-6.3). HIV-2-seropositive women were more likely to acquire HIV-1 seroreactivity than were HIV-seronegative wom en (rate ratio, 2.7; 95% CI, 0.7-11.2), but this difference was not statist ically significant (P > 0.15). Conclusion: HIV-2 infection does not appear to protect against HIV-1 infect ion.