INTERCLADE AND INTRACLADE NEUTRALIZATION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 - GENETIC CLADES DO NOT CORRESPOND TO NEUTRALIZATION SEROTYPES BUT PARTIALLY CORRESPOND TO GP120 ANTIGENIC SEROTYPES

We have studied genetic variation among clades A through E of human im munodeficiency virus type 1 (HIV-1) at the levels of antibody binding to gp120 molecules and virus neutralization, We are unable to identify neutralization serotypes that correspond to the genetic clades, Inste ad, we observe that inter- and intraclade neutralization of primary is olates by HIV-1-positive sera is generally weak and sporadic; some ser a show a reasonable degree of neutralization breadth and potency where as others are relatively sensitive to neutralization, but no consisten t pattern was found. However, a few sera were able to neutralize acros s clades with significant potency, an observation which may have impli cations for the feasibility of a broadly effective HIV-1 vaccine invol ving humoral immunity, Serological assays measuring anti-gp120 antibod y binding also failed to identify serotypes that correspond precisely to the genetic clades, but some indications of clade-specific binding were observed, notably with sera from clades B and E, A representative protein for each clade (A through E) was selected on the basis of its specificity, defined as high seroreactivity with sera from individual s infected with virus of that clade and lower reactivity with sera fro m individuals infected with viruses from other clades, The seroreactiv ity patterns against these five proteins could be used to predict the genotype of the infecting virus with moderate success.