Innate Factors in Human Breast Milk Inhibit Cell-Free HIV-1 but Not Cell-Associated HIV-1 Infection of CD4+ Cells

From the Departments of *Physiology and daggerMicrobiology and Immunology, Dartmouth Medical School, Lebanon, NH; and double daggerVA Medical Center, White River Junction, VT.

BACKGROUND:: Transmission of HIV from mother to child through breast-feeding remains a global health challenge, particularly in developing countries. Breast milk from an HIV-infected women may contain both cell-free HIV-1 and cell-associated virus; however, the impact of human Breast Milk on HIV infection and replication in CD4 cells remain poorly understood. OBJECTIVES:: In the present study, we evaluated the effects of breast milk in vitro on infection of CD4 cells with cell-free HIV-1, including effects on HIV-1 receptor expression, reverse transcription, integration, and viral transcription. Additionally, we evaluated the ability of breast milk to inhibit cell-associated transmission of HIV-1 from infected CD4 T lymphocytes.

RESULTS:: Our results demonstrate that breast milk potently inhibits infection with cell-free HIV-1 in vitro independently of viral tropism and significantly decreases HIV-1 reverse transcription and integration in CD4 cells. However, the inhibitory effect of breast milk on HIV-1 infection of CD4 cells was lost during extended culture, and direct coculture of HIV-infected CD4 T lymphocytes with susceptible target cells revealed that breast milk was ineffective at blocking cell-associated HIV-1 infection.

CONCLUSIONS:: Our findings suggest that breast milk may provide a protective function against cell-free HIV-1 but may be less effective at blocking infection by cell-associated virus.
J Acquir Immune Defic Syndr. 2009 Apr 2