NEUTRALIZATION SUSCEPTIBILITY OF B-SUBTYPE VARIANT B''-PRIMARY HIV-1 ISOLATES

Susceptibility to autologous and heterologous neutralization of primar y human immunodeficiency virus (HIV)-1 isolates belonging to subtype B , to the B''-variant of subtype B or to subtype F from infected indivi duals residing in Rio de Janeiro was assayed. A lower infectivity of t he B''- and F isolates when compared to the classical B-subtype HIV-1 isolates was observed. Comparisons of neutralization susceptibilities were carried out for 19 B-subtype, 11 B''-variant and two F-subtype HI V-1 isolates with plasma from autologous and heterologous samples. Fre quency of autologous neutralization was slightly lower for B-subtype i solates in comparison to B''-variant isolates. Heterologous intra-subt ype neutralization was significantly lower for B-subtype than for the B''-variant or the F-subtype isolates. While B-subtype isolates were n eutralized by most anti-F-subtype plasma, F-subtype isolates, although most susceptible to F-subtype antibodies, were highly susceptible to neutralization by anti-B-subtype antibodies. Cross-neutralization for B''-variant and B-subtype isolates was not as extensive as observed fo r B- and F-subtype isolates. However, the results presented indicate a quite extensive cross-neutralization between Brazilian HIV-1 isolates .