Western blot banding patterns of HIV rapid progressors in the U.S. Navy Seropositive Cohort: Implications for vaccine development

Abstract

Although human immunodeficiency virus (HIV) infection is progressive, the rate of decline in CD4 + lymphocyte counts varies. The role of immune system components in limiting HIV infection has yet to be defined, but a previous report on the U.S. Navy HIV Seropositive Cohort reported that strong reactivity in the anti-p55 (core precursor), p24 (core) and p53 (reverse transcriptase) Western blot bands was associated with higher CD4+ lymphocyte counts at the first clinical evaluation for HIV. The previous report examined the cross-sectional association between Western blot banding patterns and initial CD4+ lymphocyte counts. This report examines the association between these banding patterns in individuals who progressed rapidly as compared with patterns of patients who did not, based on their trends in repeated CD4+ lymphocyte counts as a marker of progression. Rapid and slower progressors were identified from a cohort of 3414 Navy and Marine Corps personnel who had a first positive HIV Western blot during 1986–1991. For purposes of this study, rapid progressors were defined as individuals whose CD4+ lymphocyte counts declined to < 500 cells/mm 3 within 1 year of seroconversion. A total of 325 individuals met these criteria. A comparison group of 63 slower progressors also was identified; this group consisted of those whose CD4+ lymphocyte counts remained at ⩾ 500 cells/mm 3 for a minimum of 5 years of follow-up after their first positive Western blot. Rapid processors were slightly younger than slower progressors and were more likely to be never married but did not differ significantly from slower progressors in race or sex. Rapid progressors had weaker reactivity in the anti-p55 core precursor ( P < 0.0001), p15 core ( P < 0.01), gp41 transmembrane ( P < 0.01) and p31 endonuclease ( P < 0.05) bands on the Western blot. The odds ratio for rapid progressor status associated with weak or absent reactivity was 7.8 in the anti-p55 band and ranged from 2.0 to 3.2 in the anti-p31, p15, and gp41 bands. These associations remained significant after adjustment for age, race, and sex. The p55 association persisted in repeated Western blots during routine clinical evaluation during a period of 5 years after the first positive Western blot. It was concluded that several possible explanations may account for the weaker reactivity of rapid progressors: (i) weak anti-p55 reactivity might have been a marker of early immune system damage; (ii) high concentrations of p55 or related proteins in the serum may have bound the available anti-p55 antibodies in rapid progressors, making them difficult to identify on the Western blot; or (iii) lack of anti-p55, p15, gp41, or p31 reactivity might have allowed more rapid progression.