Perinatal HIV-1 transmission: recent advances and therapeutic interventions.

OBJECTIVES: To review recent advances and current understanding of risk factors associated with perinatal HIV-1 transmission, the critical gaps in our knowledge, and current and future approaches to prevention of transmission. FACTORS INFLUENCING MOTHER-TO-CHILD TRANSMISSION: Perinatal HIV transmission is multifactorial and all potential risk factors must be considered in the context of the timing of transmission in utero, at birth or after birth by breastfeeding. Major factors that have been associated with increased transmission include a high maternal virus load, decreased CD4+ count, lack of HIV neutralizing antibody, advanced clinical disease, primary infection, first-born twins, and obstetric factors including chorioamnionitis, mode of delivery and more than 4 h of ruptured membranes. There are still significant gaps in our knowledge to explain the known variables in transmission, including the fact that 70-80% of infants born of HIV-infected mothers escape infection. APPROACHES TO REDUCE PERINATAL HIV-1 INFECTION: One of the major advances in prevention of perinatal transmission was the AIDS Clinical Trials Group 076 trial, which showed that antiretroviral therapy with zidovudine given to the mother during pregnancy and delivery, and to the infant, reduced transmission by 70%. Current approaches to further reduce transmission and provide practical application worldwide are discussed, including combined potent antivirals, local approaches and immune-based therapy given to the mother and/or infant.
CONCLUSIONS: There is reason for optimism for the potential to further reduce perinatal transmission to a level of less than 2%. The challenge will be to increase education and awareness worldwide in order to translate scientific advances into practical approaches that will be applicable in both industrialized and non-industrialized countries.