Influence of IFNγ Co-Expression on the Safety and Antiviral Efficacy of Recombinant Fowlpox Virus HIV Therapeutic Vaccines Following Interruption of Antiretroviral Therapy
Volume 3, Issue 6
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Pages 260 - 267
Authors: S. Emery, A.D. Kelleher, C. Workman, R.L. Puls, M. Bloch, D. Baker, J. Anderson, J. Hoy, S. Ip, K. Nalliah, L.D. Ward, M.G. Law and D.A. Cooper View affiliations
Therapeutic immunization to stimulate host immune responses and control human immunodeficiency virus (HIV-1) replication is being investigated as a supplimentary treatment for the management of HIV infection.
On completion of an earlier study involving three vaccinations while taking combination antiretroviral therapy (CART), twenty-five subjects with plasma viral load (pVL) <50 copies/mL received a booster vaccination with either placebo (n=7); fowl pox vaccine (rFPV) expressing HIV-1 Gag/Pol; (partial construct- PC (n=8)) or rFPV co-expressing HIV-1 Gag/Pol and human interferon-γ (full construct FC (n=10)). One week after the booster vaccination, participants stopped ART and were monitored for safety, pVL and immunological parameters for < 20 weeks.
The time weighted mean change (SD) from baseline plasma HIV RNA was 1.80 (0.72), 1.78 (0.91) and 0.96 (0.91) log10 copies/mL for placebo, PC and FC recipients respectively (p=0.06; mean differences between placebo and FC). Laboratory evaluations did not reveal differences in anti-HIV specific immune responses between study arms. No difference between treatment arms for host genetic factors known to affect pVL was demonstrated.
In conclusion, vaccination with FC was associated with a trend toward lower rates of HIV replication following cessation of ART relative to placebo or PC. The promising antiretrovirological effect supports further study of FC in a larger trial with a broader population of patients with HIV disease.
Received: May 5, 2007; Accepted: June 25, 2007