Safety and immunogenicity of a modified pox vector-based HIV/AIDS vaccine candidate expressing Env, Gag, Pot and Nef proteins of HIV-1 subtype B (MVA-B) in healthy HIV-1-uninfected volunteers: A phase I clinical trial (RISVAC02)

Background: To investigate the safety and immunogenicity of a modified vaccinia virus Ankara vector expressing HIV-1 antigens from clade B (MVA-B), a phase-I, doubled-blind placebo-controlled trial was performed. Methods: 30 HIV-uninfected volunteers at low risk of HIV-1 infection were randomly allocated to receive 3 intramuscular injections (1 x 10(8) pfu/dose) of MVA-B (n = 24) or placebo (n = 6) at weeks 0,4 and 16. All volunteers were followed 48 weeks. Primary end-points were adverse events and immunogenicity. Results: A total of 169 adverse events were reported, 164 of grade 1-2, and 5 of grade 3 (none related to vaccination). Overall 75% of the volunteers showed positive ELISPOT responses at any time point. The magnitude (median) of the total responses induced was 288 SFC/10(6) PBMC at week 18. Antibody responses against Env were observed in 95% and 72% of vaccinees at week 18 and 48, respectively. HIV-1 neutralizing antibodies were detected in 33% of volunteers. Conclusions: MVA-B was safe, well tolerated and elicited strong and durable T-cell and antibody responses in 75% and 95% of volunteers, respectively. These data support further exploration of MVA-B as an HIV-1 vaccine candidate. Clinical Trials.gov identifier: NCT00679497. (C) 2011 Elsevier Ltd. All rights reserved.