793b    

Background:  The rationale for using HAART to prevent mother-to-child HIV transmission (MTCT) during breastfeeding depends upon its ability to reduce cell-free HIV-1 RNA, and possibly cell-associated HIV-1 DNA, in breast milk. The ability of HAART to reduce HIV-1 RNA and DNA in breast milk has not been described previously.

Methods:  We performed a nested cohort study among breastfeeding women enrolled in a randomized clinical trial for the prevention of MTCT in Botswana. We compared whole breast milk HIV-1 RNA and DNA levels among 26 women with AIDS who received HAART (nevirapine, lamivudine, and zidovudine) and a similar group of 25 women who did not receive HAART because they participated in the trial before HAART became available in October 2002. Breast milk collection occurred at either 2 or 5 months postpartum. Treated women began HAART in pregnancy or the postpartum period, at least 2 months prior to breast milk collection.

Results:  Twenty-four (92%) of 26 women in the HAART group had plasma HIV-1 RNA < 400 copies/mL within 2 months of breast-milk sampling, compared with 1 (4%) of 25 who did not receive HAART. Women in the HAART group received treatment for a median of 98 days (range 67 to 222 days) at the time of breast-milk sampling; 23 (88%) of 26 had whole breast milk HIV-1 RNA < 50 copies/mL, compared with 9 (36%) of 25 women who did not receive HAART (p = 0.0001). In a multivariate logistic regression model controlling for baseline CD4 cell count and baseline plasma HIV-1 log RNA, the receipt of HAART remained significantly associated with suppression of breast milk HIV-1 RNA to < 50 copies/mL (p = 0.001). Breast milk supernatant results were similar to those for whole milk. In contrast, whole milk HIV-1 DNA was unaffected by HAART. Among women who received HAART, only 13 (50%) of 26 had HIV-1 DNA < 10 copies/mL, compared with 15 (65%) of 23 of those who did not receive HAART (p = 0.28).

Conclusions:  HAART effectively suppressed cell-free HIV-1 RNA in whole breast milk and breast milk supernatant, and may therefore reduce the risk of MTCT during breastfeeding. However, HAART initiated in pregnancy or the early postpartum period had no apparent effect on cell-associated HIV-1 DNA in breast milk. The relative contribution of cell-free and cell-associated HIV-1 to MTCT during breastfeeding requires further study, and clinical trials to determine MTCT rates among breastfeeding women receiving HAART are needed.

Keywords: Breast Milk; MTCT; Transmission