Advances in basic science understanding of mother-to-child HIV-1 transmission.
OBJECTIVE
The present review summarizes and discusses studies on the mechanisms underlying mother-to-child HIV transmission published in 2006-2007.


RESULTS
Many studies have focused on the pathogenesis of breast milk transmission. Recent analyses comparing cell-free and cell-associated virus in milk suggest that cell-associated virus may play a greater role in transmission than previously appreciated. Transmitted HIV variants appear to be resistant to neutralizing maternal antibodies and have enhanced replicative capacity suggesting greater fitness. Several adaptive and innate immune factors were identified that enhanced or impeded transmission.


CONCLUSIONS
Advances have been made in delineating the risk and protective factors mediating mother-to-child transmission. Many questions, however, still remain unanswered. Understanding the immune mechanisms that prevent most children from becoming infected with HIV and the properties of viruses that 'pass through the gauntlet' are central to prevention efforts.
Walter
Jan
J
aChildren's Hospital Los Angeles, University of Southern California, Los Angeles, California, USA bGertrude H. Sergievsky Center, and Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA.
Kuhn
Louise
L
Aldrovandi
Grace M
GM