High Maternal HIV-1 Viral Load During Pregnancy Is Associated With Reduced Placental Transfer of Measles IgG Antibody

During the past decade the HIV epidemic has resulted in increased infant mortality in sub-Saharan Africa and has reversed gains made in part through childhood immunization programs. Infants born to HIV-1–infected mothers have a ~2- to 3-fold increased risk of death, and HIV-1–exposed, uninfected infants tend to have higher rates of hospitalization, severe pneumonia, and measles.1–4 A Malawian study reported a ~4-fold increased risk of measles among HIV-1–infected infants and a ~2-fold increased risk among HIV-1–exposed uninfected infants compared with infants born to HIV-1–uninfected women.1 Measles also occurs at a younger age among HIV-1–infected infants, with up to one-third of cases reported before 9 months of age, and infection is more likely to result in death with maternal HIV-1 infection regardless of infant HIV-1 status.5–7 Maternal immunosuppression and HIV-1 viremia may influence infectious morbidity among infants by reducing passively acquired humoral immunity against important pathogens, including measles. It has previously been reported that placental transfer of IgG against measles virus is lower among HIV-1–infected than HIV-1–uninfected women8 and that concentrations of measles IgG prior to immunization are reduced among HIV-1–exposed infants compared with infants born to HIV-1–seronegative mothers.9,10 However, determinants of reduced placental transfer among HIV-1–infected women are not well characterized. In this study, we hypothesized that women with advanced HIV-1 infection would have the greatest reductions in transplacental transfer of measles IgG. In a cohort of HIV-1–infected mothers and their infants, we evaluated the relationship between placental IgG transfer, infant measles antibody concentrations, and several modifiable and nonmodifiable factors, including maternal CD4+ T-cell count, HIV-1 viral load, and IgG directed against HIV-1 gp41.