Immunization with envelope MN rgp120 vaccine in human immunodeficiency virus-infected pregnant women

Twenty-six human immunodeficiency virus (HIV)-infected pregnant women parti cipated in a placebo-controlled study of immunogenicity and safety of multi ple doses of MN rgp120 vaccine over the last half of pregnancy. The women h ad CD4 lymphocyte counts >400/mm(3), no AIDS-defining illness and normal pr egnancies. Vaccination was well tolerated, with no significant local or sys temic reactions in the women and no adverse outcomes in the infants attribu table to the vaccine. Vaccination did not alter plasma RNA reverse transcri ptase-polymerase chain reaction copy number; moreover, immunization was not associated with changes in CD4 counts or HIV binding and neutralization an tibody titers, Infants were followed up until 18 months of age. Five of 26 infants (19%) were HIV infected, with infection occurring in children of bo th vaccinated and placebo women. Analysis of factors that influence transmi ssion did not disclose associations with immunization status, viral load, C D4 count, or maternal viral neutralization titers.