Neutralizing antibodies in slowly progressing HIV-1 infection

Ten asymptomatic individuals who had experienced only limited CD4+ cell loss after prolonged infection with HIV-1 were studied. These individuals had a mean CD4+ cell count of 674 x 10(6) cells/L and a mean duration of infection of 8.5 years. Also included were 10 asymptomatic HIV-1-infected individuals who, over a similar period of infection (7.5 years), had experienced a profound loss of CD4+ cells (mean CD4+ cell count, 54 x 10(6) cells/L). Proviral load was determined using a semiquantitative polymerase chain reaction and was significantly lower in the subjects with slowly progressing infection (SPI) than in subjects with rapidly progressing infection (RPI) (4,000 vs. 40,000 proviral copies/10(6) peripheral blood mononuclear cells; p = 0.0089). Isolation of virus was attempted in all individuals but succeeded only in 6 of 10 individuals with SPI versus all 10 individuals with RPI. Four of six virus isolates obtained from individuals with SPI and 6 of 10 obtained from individuals with RPI were of the syncytia-inducing phenotype. We determined the neutralizing activity of serum against HIVMN, HIVIIIB, and the contemporaneous autologous isolate when available. Serum from individuals with SPI generally neutralized the contemporaneous isolate, whereas serum from individuals with RPI did not [geometric mean antibody titer (GMT), 45 vs. 3; p = 0.0047]. There was no difference in neutralizing ability against HIVMN (GMT,2,593 vs. 2,263; p = 0.74) and only a small difference against HIVIIIB (GMT, 115 vs. 50; p = 0.075). Our results indicate that individuals with SPI are characterized by an ability to neutralize their own HIV strain.(ABSTRACT TRUNCATED AT 250 WORDS)