Human immunodeficiency virus (HIV) type 1 strain MN neutralizing antibody in HIV-infected children: correlation with clinical status and prognostic value.

Protective immunity to human immunodeficiency virus (HIV) was examined in 228 serial sera from 58 HIV-infected children before and during antiretroviral therapy. Binding antibodies to putative protective V3 epitopes of HIV-1IIIB and HIV-1MN were investigated by a peptide ELISA, and neutralizing antibodies by inhibition of HIV-1MN cell-free viral infection. No difference in binding of total IgG or IgG subclasses was observed between patients with mild (group A) or advanced disease (group B). However, group A patients were more likely to possess neutralizing antibody titers > or = 225 (P = .040 after adjustment for CD4). This threshold titer also predicted clinical outcome in patients with age-adjusted CD4 count > 10% of normal median. Patients with titers < 225 more frequently encountered major clinical events during follow-up than did patients with titers > or = 225 (P = .0028). Epitopes other than the linear V3 loop contribute to this protective immune response. Identification of these epitopes should assist immune therapy of AIDS and HIV vaccine development.