Journal Article

An Ad5-Vectored HIV-1 Vaccine Elicits Cell-mediated Immunity but does not Affect Disease Progression in HIV-1–infected Male Subjects: Results From a Randomized Placebo-Controlled Trial (The Step Study)

D. W. Fitzgerald, H. Janes, M. Robertson, R. Coombs, I. Frank, P. Gilbert, M. Loufty, D. Mehrotra and A. Duerr

in The Journal of Infectious Diseases

Published on behalf of Infectious Diseases Society of America

Volume 203, issue 6, pages 765-772
Published in print March 2011 | ISSN: 0022-1899
Published online March 2011 | e-ISSN: 1537-6613 | DOI:

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(See the editorial commentary by Altfeld and Goulder, on pages 753–5.)

Background. The Step study was a randomized trial to determine whether an adenovirus type 5 (Ad5) vector vaccine, which elicits T cell immunity, can lead to control of human immunodeficiency virus (HIV) replication in participants who became HIV-infected after vaccination.

Methods. We evaluated the effect of the vaccine on trends in HIV viral load, CD4+ T cell counts, time to initiation of antiretroviral therapy (ART), and AIDS-free survival in 87 male participants who became infected with HIV during the Step study and who had a median of 24 months of post-infection follow-up.

Results. There was no overall effect of vaccine on mean log10 viral load (estimated difference between groups, -0.11; P = .47). In a subset of subjects with protective HLA types (B27, B57, B58), mean HIV-1 RNA level over time was lower among vaccine recipients. There was no significant difference in CD4+ T cell counts, time to ART initiation, or in AIDS-free survival between HIV-1–infected subjects who received vaccine versus those who received placebo.

Conclusions. HIV RNA levels, CD4+ T cell counts, time to initiation of ART, and AIDS-free survival were similar in vaccine and placebo recipients. There may have been a favorable effect of vaccine on HIV-1 RNA levels in participants with HLA types associated with better control of HIV-1.

Journal Article.  4608 words.  Illustrated.

Subjects: Infectious Diseases ; Immunology ; Public Health and Epidemiology ; Microbiology