Recombinant fowlpox virus vector-based vaccines: expression kinetics, dissemination and safety profile following intranasal delivery.

We have previously established that mucosal uptake of recombinant fowlpox virus (rFPV) vaccines is far superior to other vector-based vaccines. Specifically, intranasal priming with rFPV vaccines can recruit unique antigen-presenting cells, which induce excellent mucosal and systemic HIV-specific CD8+ T-cell immunity. In this study, we have for the first time investigated the in vivo dissemination, safety and expression kinetics of rFPV post intranasal delivery using recombinant viruses expressing green fluorescent protein or mCherry. Both confocal microscopy of tissue sections using green fluorescent protein and in vivo Imaging System (IVIS) spectrum live animal and whole organ imaging studies using mCherry revealed that (i) the peak antigen expression occurs 12 to 24 h post vaccination and no active viral gene expression is detected 96 h post vaccination. (ii) The virus only infects the initial vaccination site (lung and nasal cavity) and does not disseminate to distal sites such as the spleen or gut. (iii) More importantly, rFPV does not cross the olfactory receptor neuron pathway. Collectively, our findings indicate that rFPV vector-based vaccines have all the hallmarks of a safe and effective mucosal delivery vector, suitable for clinical evaluation.

A phase 1/2 comparative vaccine trial of the safety and immunogenicity of a CRF01_AE (subtype E) candidate vaccine: ALVAC-HIV (vCP1521) prime with oligomeric gp160 (92TH023/LAI-DID) or bivalent gp120 (CM235/SF2) boost.

BACKGROUND: The development of an effective HIV-1 vaccine is critical to control the pandemic. A prime-boost HIV-1 vaccine trial assessing safety and immunogenicity was conducted in Thailand as part of an evaluation of candidate regimens for a phase 3 efficacy trial. METHODS: ALVAC-HIV (vCP1521), expressing circulating recombinant form 01_AE (CRF01_AE) gp120/subtype B LAI and subtype B Gag/Protease boosted with recombinant envelope oligomeric CRF01_AE gp160 (ogp160) or bivalent CRF01_AE/subtype B gp120 CM235/SF2, was evaluated in a phase 1/II trial of 130 HIV-negative Thai adults. RESULTS: One hundred forty volunteers were enrolled, and 130 completed all safety and immunogenicity visits. Reactogenicity was common but generally mild, and there was no significant difference in the adverse event rate between vaccine and placebo recipients (P = 0.26). There were 7 serious adverse events during the follow-up period, none of which were vaccine related. Cumulative HIV-specific, CD8-mediated, cytotoxic T-lymphocyte responses were observed in 11 (25%) of 44 subjects who received ALVAC boosted by bivalent gp120 and in 5 (11%) of 45 subjects who received ALVAC boosted by ogp160, but these differences were not statistically significant compared with those in placebo recipients (P = 0.62 and P = 0.37, respectively). HIV-specific lymphoproliferative responses were detected in 84% of subunit-boosted vaccine recipients and in 10% of placebo recipients. Neutralizing antibody responses to CRF01_AE and subtype B laboratory strains were seen in 95% of ogp160-boosted and 100% of gp120 B/E-boosted vaccinees, respectively. CONCLUSIONS: These 2 different prime-boost regimens seem to be safe and displayed cell-mediated immune responses consistent with those in other trials of canarypox vectors.

Preclinical and clinical studies on immunogenicity and safety of the HIV-1 p17-based synthetic peptide AIDS vaccine--HGP-30-KLH.

Immunization with a synthetic HIV-1 p17 peptide analog (HGP-30; aa 85-115 of HIV p17), coupled to a carrier protein (KLH, keyhole limpet hemocyanin) given with alum as the adjuvant induces antibodies which cross-react with both HGP-30 and HIV p17 and clones of cytotoxic and helper T-cells which recognize HGP-30 and HIV p17. Proliferation of lymphocytes in response to HGP-30 has been observed in mice, in HIV-infected individuals and in healthy HIV-seronegative volunteers vaccinated with the p17-based synthetic peptide construct. Cytotoxic T-cell responses against EBV transformed, recombinant p17 pulsed targets were observed using antigen-expanded PBLs from HGP-30-KLH immunized individuals. These results are consistent with predictions that the HGP-30 domain of HIV p17 contains both T- and B-cell epitopes that are recognized by animals and humans. In preclinical toxicology studies in animals and in initial clinical trials in humans the synthetic peptide construct (HGP-30-KLH/alum) has been shown to be safe. This paper summarizes the preclinical immunogenicity and safety data for HGP-30-KLH and presents the initial results from the first Phase 1 clinical trial.