AEGiS-15IAC: Breast milk transmission of free and cell-associated HIV in different postpartum periods.

15th International AIDS Conference

Bangkok, Thailand - July 11-16, 2004

Breast milk transmission of free and cell-associated HIV in different postpartum periods.

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. ThOrC1417)

Koulinska IN, Villamor E, Msamanga GI, Fawzi WW, Renjifo B, Essex M
Harvard School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA, United States

BACKGROUND: HIV-1 transmission by breastfeeding is associated with high viral and proviral load in milk. Although cell numbers in milk tend to decrease over time, a constant risk of HIV infection has been reported between 6 weeks and 24 months postpartum. Relative transmission rates of free virus and infected cells might vary in different postpartum periods.

METHODS: A case-control study nested within a vitamin supplementation trial in Tanzania included 63 HIV-positive mothers whose infants tested PCR-positive only after 6 weeks of age. They were matched to 63 breastfeeding non-transmitting mothers on providing a sample within 1 week of the estimated transmission time for the case. Viral and proviral levels in milk were measured by the Roche Amplicor Monitor 1.5 kit and by real-time PCR, respectively. The C2-C5 env region was amplified from HIV RNA and DNA in milk of transmitting mothers and the cloned sequences were phylogenetically compared to those found in infant PBMCs.

RESULTS: After adjustment for vitamin A supplementation, CD4 counts, and disease stage, proviral and free viral levels were similarly associated with HIV transmission by breast milk, OR=2.18 (95% CI 1.15-4.13) and OR=2.45 (95% CI 1.22-4.93). However, transmission occurring before 9 months postpartum was more strongly associated with proviral than free viral load, OR=6.0 (95% CI 1.34-26.80) vs OR=2.8 (95% CI 1.01-7.77). Although both viral RNA and DNA levels were significant predictors of infant infection after 9 months of age, the association tended to be stronger for HIV RNA concentrations, OR=4.67 (95%CI 1.34-16.24) vs OR=3.25 (95%CI 1.06-9.97). Infants harboring viruses that clustered with milk viral RNA tended to be infected after 9 months postpartum (9/14, 63%). No such trend was observed for variants clustering with milk provirus.

CONCLUSIONS: Although infant infection with milk HIV free virus and provirus can occur at any time during breastfeeding, transmission of free virus seems to be facilitated after 9 months postpartum.

Keywords: AEGIS, HIV, HIV Seropositivity, Acquired Immunodeficiency Syndrome, Milk, Human, HIV Infections, HIV-1, Breast Feeding, Viral Load, CD4 Lymphocyte Count, RNA, Viral, Mothers, Virus Diseases, HIV Antibodies, Infant Food, Infant Nutrition, Case-Control Studies, Tanzania, Infant, Humans, transmission, immunology

040711
ThOrC1417