Safety and Immunogenicity of a Randomized Phase 1 Prime-Boost Trial With ALVAC-HIV (vCP205) and Oligomeric Glycoprotein 160 From HIV-1 Strains MN and LAI-2 Adjuvanted in Alum or Polyphosphazene.

BACKGROUND: Prime-boost regimens comprising ALVAC-HIV (prime) and human immunodeficiency virus type 1 (HIV) Env (boost) induce HIV-specific neutralizing antibody and cell-mediated immune responses, but the impact of boost schedule and adjuvant requires further definition. METHODS: A phase 1 trial was conducted. In part A (open label), 19 volunteers received oligomeric glycoprotein 160 from HIV strains MN and LAI-2 (ogp160 MN/LAI-2) with dose escalation (25, 50, 100 µg) and either polyphosphazene (pP) or alum adjuvant. In part B, 72 volunteers received either placebo (n=12) or recombinant canarypox virus expressing HIV antigens (ALVAC-HIV [vCP205]) with different doses and schedules of ogp160 MN/LAI-2 in pP or alum (n = 60). RESULTS: The vaccines were safe and well tolerated, with no vaccine-related serious adverse events. Anti-gp70 V1V2 antibody responses were detected in 17 of 19 part A volunteers (89%) and 10%-100% of part B volunteers. Use of a peripheral blood mononuclear cell-based assay revealed that US-1 primary isolate neutralization was induced in 2 of 19 recipients of ogp160 protein alone (10.5%) and 5 of 49 prime-boost volunteers (10.2%). Among ogp160 recipients, those who received pP were more likely than those who received alum to have serum that neutralized tier 2 viruses (12% vs 0%; P = .015). CONCLUSIONS: Administration of ogp160 with pP induces primary isolate tier 2 neutralizing antibody responses in a small percentage of volunteers, demonstrating proof of concept and underscoring the importance of further optimization of prime-boost strategies for HIV infection prevention. CLINICAL TRIALS REGISTRATION: NCT00004579.

Co-immunization with multimeric scaffolds and DNA rapidly induces potent autologous HIV-1 neutralizing antibodies and CD8+ T cells.

To obtain proof of concept for HIV vaccines, we generated recombinant multimeric particles displaying the HIV-1 Envelope (Env) third hypervariable region (V3) as an N-terminal fusion protein on the E2 subunit of the pyruvate dehydrogenase complex of Geobacillus stearothermophilus. The E2 scaffold self-assembles into a 60-mer core that is 24 nm in diameter, with a molecular weight of 1.5 MDa, similar to a virus like particle with up to 60 copies of a heterologous protein accessible on the surface. Env(V3)-E2 multimers were tested alone and in combination with Env(gp160) DNA in mice and rabbits. Following two or more co-immunizations with Env(V3)-E2 and Env gp160 DNA, all 18 rabbits developed potent autologous neutralizing antibodies specific for V3 in six weeks. These neutralizing antibodies were sustained for 16 weeks without boosting, and comparable responses were obtained when lipopolysaccharide, a contaminant from expression in E. coli, was removed. Co-immunizations of Env(V3)-E2 and DNA expressing gp160 elicited moderate CD8-specific responses and Env-specific antibodies in mice. Co-immunization with DNA and E2 was superior to individual or sequential vaccination with these components in eliciting both neutralizing antibodies in rabbits and CD8(+) T cell responses in mice. Co-immunization with DNA and multimeric E2 scaffolds appears to offer a highly effective means of eliciting rapid, specific, and sustained immune responses that may be a useful approach for other vaccine targets.

Prime-boost vaccination with heterologous live vectors encoding SIV gag and multimeric HIV-1 gp160 protein: efficacy against repeated mucosal R5 clade C SHIV challenges.

We sought to induce primate immunodeficiency virus-specific cellular and neutralizing antibody (nAb) responses in rhesus macaques (RM) through a bimodal vaccine approach. RM were immunized intragastrically (i.g.) with the live-attenuated Listeria monocytogenes (Lm) vector Lmdd-BdopSIVgag encoding SIVmac239 gag. SIV Gag-specific cellular responses were boosted by intranasal and intratracheal administration of replication-competent adenovirus (Ad5hr-SIVgag) encoding the same gag. To broaden antiviral immunity, the RM were immunized with multimeric HIV clade C (HIV-C) gp160 and HIV Tat. SIV Gag-specific cellular immune responses and HIV-1 nAb developed in some RM. The animals were challenged intrarectally with five low doses of R5 SHIV-1157ipEL-p, encoding a heterologous HIV-C Env (22.1% divergent to the Env immunogen). All five controls became viremic. One out of ten vaccinees was completely protected and another had low peak viremia. Sera from the completely and partially protected RM neutralized the challenge virus > 90%; these RM also had strong SIV Gag-specific proliferation of CD8⁺ T cells. Peak and area under the curve of plasma viremia (during acute phase) among vaccinees was lower than for controls, but did not attain significance. The completely protected RM showed persistently low numbers of the α4ß7-expressing CD4⁺ T cells; the latter have been implicated as preferential virus targets in vivo. Thus, vaccine-induced immune responses and relatively lower numbers of potential target cells were associated with protection.

Long-term increase of CD4+ central memory cells in HIV-1-infected individuals by therapeutic HIV-1 rgp160 immunization.

OBJECTIVE: To evaluate functional potential and phenotypic markers in HIV-1-infected patients immunized with HIV-1 rgp160. METHODS: We assessed changes in T-cell phenotype and immune function in 12 HIV-1-infected individuals that were part of a therapeutic vaccine study from 1992 to 1995 [Sandstrom E, Wahren B. Therapeutic immunisation with recombinant gp160 in HIV-1 infection: a randomised double-blind placebo-controlled trial. Nordic VAC-04 Study Group. Lancet 1999;353(9166):1735-42]. The patients received 160 microg HIV-1 rgp160 or placebo i.m. at baseline (day 0), and months 1, 2, 3, 4, 6, and thereafter every 3 months. Frozen peripheral blood mononuclear cells (PBMC) were retrieved from time points 0, 9, 12 and 24 months for phenotypic analysis utilizing flow cytometry. RESULTS: Up-regulation of immune activation markers HLA-DR and CD38 was observed at baseline and throughout the monitoring period on both CD4+ and CD8+ T cells in all patients, reflecting immune activation due to persistent high viral load. Further enhanced expression of activation markers was observed over time in the vaccine group, but not the placebo group. We also observed a consistent long-term increase of the CD4+ central memory population (CD3+CD4+CD45RA-CCR7+) in the vaccinated group. CONCLUSIONS: Administration of eight doses of rgp160 in a year appeared to partially reverse some of the defects exerted by HIV-1 on the immune system. A combination of vaccination with effective antiretroviral therapy (ART) may thus represent an immunotherapeutic intervention for treatment of chronic HIV-1 infection. The improvement of a HIV-1-specific central memory population and HIV-1 antigen-specific CD4+ lymphoproliferative responses may have contributed to the short-term improved survival reported in the vaccinated group.

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.

Liposome-stabilized oil-in-water emulsions as adjuvants: increased emulsion stability promotes induction of cytotoxic T lymphocytes against an HIV envelope antigen.

Protective or therapeutic immunity against HIV infection is currently believed to require both antibody and CTL responses against the envelope protein. In the present study, the adjuvant activity of a unique oil-in-water emulsion, in which liposomes containing lipid A (LA) and encapsulated antigen served as the emulsifying agent, was examined in mice using oligomeric gp140 (ogp140) derived from the HIV-1 envelope as the antigen. Emulsions rendered either highly stable or unstable by altering the ratio of liposomes to oil were used to examine the effect of stability of the emulsion on adjuvant activity. Stable and unstable emulsions had similar potencies for inducing both IgG antibodies to ogp140 and antigen-specific T-lymphocyte proliferation. Stable emulsions, but not unstable emulsions, induced antigen-specific CTL responses, possibly because of the depot effect of the stable emulsions. Furthermore, stable emulsions induced lower IgG2a/IgG1 ratios than the unstable emulsions. We conclude that stable liposomal oil-in-water emulsions provide an effective means of obtaining both antibody and CTL responses against an HIV envelope antigen.

HIV mucosal vaccine: nasal immunization with gp160-encapsulated hemagglutinating virus of Japan-liposome induces antigen-specific CTLs and neutralizing antibody responses.

Nasal immunization of normal mice with HIVgp160-encapsulated hemagglutinating virus of Japan (HVJ)-liposome induced high titers of gp160-specific neutralizing IgG in serum and IgA in nasal wash, saliva, fecal extract, and vaginal wash, along with both Th1- and Th2-type responses. HIVgp160-specific IgG- and IgA-producing cells were also detected in mononuclear cells isolated from spleen, nasal cavity, salivary gland, intestinal lamina propria, and vaginal tissue of nasally immunized mice. In addition, CD8(+) CTLs were induced in mice nasally immunized with gp160-HVJ-liposome. These findings suggest that two layers of effective HIV-specific humoral and cellular immunity, in mucosal and systemic sites, were induced by this nasal vaccine. In immunodeficient mice, nasal immunization with gp160-HVJ-liposome induced Ag-specific immune responses for the systemic and mucosal compartments of both Th1 (IFN-gamma(-/-)) and Th2 (IL-4(-/-)). In vitro Ag-specific serum IgG Ab and vaginal wash samples possessing IgA and IgG Abs that had been induced by nasal immunization with gp160-HVJ-liposome were able to neutralize a clinically isolated strain of HIV-MN strain isolated from Japanese hemophiliac patients. Taken together, these results suggest that, for the prevention and control of AIDS, nasally administered gp160-HVJ-liposome is a powerful immunization tool that induces necessary Ag-specific immune responses at different stages of HIV infection.

Topical application of HIV DNA vaccine with cytokine-expression plasmids induces strong antigen-specific immune responses.

The topical application of DNA vaccine to the skin is a useful method of immunization because of its simplicity, painlessness and economy. But the immune responses that it elicits are relatively low. In this study, we administered human immunodeficiency virus type-1 (HIV-1) DNA vaccine with cytokine-expressing plasmids to the skin of mice by a new topical application technique involving prior elimination of keratinocytes using fast-acting adhesive. Our results revealed that the topical application of HIV-1 DNA vaccine induced high levels of both humoral and cell-mediated immune activity against HIV-1 envelope antigen. Co-administration of the DNA vaccine with cytokine expression plasmids of IL-12 and granulocyte-macrophage colony-stimulating factor (GM-CSF) by this new method raised the levels of both the HIV-specific cytotoxic T lymphocyte (CTL) response and delayed-type hypersensitivity (DTH) and facilitated the induction of substantial immune responses by DNA vaccine. Skin biopsy sections, thus, immunized showed significant increases of S-100 protein-positive dendritic cells (DCs). These results suggest that the topical application method described here is an efficient route of DNA vaccine administration and that the immune response may be induced by DNA plasmids taken in by DCs, Langerhans cells (LCs), or others such as antigen-presenting cells. This new topical application is likely to be of benefit in clinical use.

Vaccine protection against a heterologous, non-syncytium-inducing, primary human immunodeficiency virus.

Vaccine-induced protection of chimpanzees against laboratory-adapted and syncytium-inducing, multiply passaged primary human immunodeficiency virus type 1 (HIV-1) isolates, but not against non-syncytium-inducing, minimally passaged ones, has been demonstrated. Following challenge with such an isolate, HIV-15016, we obtained complete protection in one of three chimpanzees previously protected against low- and high-dose HIV-1SF2 exposures after immunization with an adenovirus-HIV-1MN gp160 priming-HIV-1SF2 gp120 boosting regimen. At challenge, the protected chimpanzee exhibited broad humoral immunity, including neutralizing antibody activity. These results demonstrate the potential of this combination vaccine strategy and suggest that vaccine protection against an HIV isolate relevant to infection of people is feasible.

Long-term evaluation of cellular immunity during antiretroviral therapy and immunization with human immunodeficiency virus type 1 (HIV-1) Env glycoprotein in HIV-1-infected persons.

Cellular immune responses to human immunodeficiency virus type 1 (HIV-1) antigens, microbial recall antigens, and CD3 monoclonal antibody were studied in HIV-1-infected asymptomatic patients in a phase II, double-blind trial of immunization with recombinant HIV-1 gp160 in or not in association with zidovudine. A vigorous and persistent lymphoproliferative response (LPR) to HIV-1 Env antigens was observed in vaccinated patients. Neither Env-specific lymphocyte cytotoxicity nor LPR to recall antigens was significantly influenced by gp160 administration. The induction of LPRs to HIV-1 envelope proteins did not show positive effects on the course of HIV-1 infection. Patients treated with zidovudine alone or in combination with the immunogen showed improvement of T lymphocyte responses and transient reduction of viremia. These results suggest that antiretroviral therapy is more beneficial than immunization with gp160 and should always be considered in association with future vaccination and immunotherapeutic interventions in HIV-1-infected subjects.