Antibody Titers in Infants Born to HIV-Positive Women

HIV-negative infants of HIV-positive women are vulnerable to infectious illnesses, with high rates of pneumonia, meningitis, and death during the first year of life. To develop new strategies for protecting these infants, we need to understand how maternal HIV infection influences infant immune responses. Toward that end, investigators studied antibody titers to vaccine-preventable diseases in women and infants seen at a community health center in South Africa. In 2009, 32% of women attending prenatal clinics in that region were HIV positive, and the HIV vertical transmission rate was 3.3%.

Serum samples for antibody testing were collected from infants and their mothers ≤24 hours after delivery; follow-up samples were collected from the infants at 16 weeks. Infants born to HIV-positive mothers had HIV polymerase chain reaction performed at 4 and 16 weeks; only those who tested negative were included in the analysis.

Antibody titers against Haemophilus influenzae type B (Hib), Bordetella pertussis, Streptococcus pneumoniae, and tetanus toxoid were significantly lower in the 46 infants born to HIV-positive mothers than in the 54 born to HIV-negative mothers. The HIV-positive mothers had reduced antibody levels to Hib and S. pneumoniae but not to B. pertussis or tetanus toxoid; however, an analysis of infant:maternal antibody-level ratios showed a significant reduction in placental transfer of all four of these specific antibodies. The HIV-exposed infants did have robust antibody responses after immunization with the four corresponding vaccines.