Short communication: effect of short-course antenatal zidovudine and single-dose nevirapine on the BED capture enzyme immunoassay levels in HIV type 1 subtype C infection.

Cross-sectional prevalence studies based on immunoassays that discriminate between recent and long-term infections, such as the BED assay, have been widely used to estimate HIV incidence. However, individuals receiving highly active antiretroviral therapy tend to have lower BED levels and are associated with a higher risk for being mistakenly classified as recent infections. To assess the effect of short-term antenatal zidovudine (ZDV) and single-dose nevirapine (sdNVP) on the BED levels in HIV-1C infection, we measured longitudinal BED normalized optical density (OD-n) levels using stored plasma samples collected prenatally and postnatally from 159 pregnant HIV-infected women in Botswana who participated in the randomized clinical Mother-to-Child-Prevention study, the Mashi study. All women received ZDV from 34 weeks gestation through delivery and were randomized to receive either sdNVP or placebo during labor. Among 159 subjects, the OD-n levels decreased from baseline to delivery in 93 subjects (p=0.039), suggesting that short-course ZDV may decrease OD-n levels. sdNVP at delivery did not affect longitudinal BED OD-n levels postdelivery. However, sdNVP appeared to modify the association between CD4 count at delivery and OD-n levels postdelivery. When estimating HIV incidence with the BED assay, special care may be required regarding women who received short-term ZDV for prevention of mother-to-child transmission.