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A combination AIDS vaccine approach consisting of priming with adenovirus-HIV-1MN gp160 recombinants followed by boosting with HIV-1SF2 gp120 was evaluated in chimpanzees. Long-lasting protection, requiring only three immunizations, was achieved against a low-dose challenge with the SF2 strain of HIV-1 and a subsequent high-dose SF2 challenge administered 1 year later without an intervening boost. Notably, neutralizing antibody responses against both clinical and laboratory isolates developed in three chimpanzees and persisted until the time of high-dose challenge. The possibility that cytotoxic T-lymphocytes contribute to low-dose protection of a chimpanzee lacking neutralizing antibodies is suggested. Our results validate the live vector priming/subunit booster approach and should stimulate interest in assessing this combination vaccine approach in humans.

BackgroundDNA vaccines are a promising approach to vaccination since they circumvent the problem of vector-induced immunity. DNA plasmid cytokine adjuvants have been shown to augment immune responses in small animals and in macaques.Methodology/Principal FindingsWe performed two first in human HIV vaccine trials in the US, Brazil and Thailand of an RNA-optimized truncated HIV-1 gag gene (p37) DNA derived from strain HXB2 administered either alone or in combination with dose-escalation of IL-12 or IL-15 plasmid cytokine adjuvants. Vaccinations with both the HIV immunogen and cytokine adjuvant were generally well-tolerated and no significant vaccine-related adverse events were identified. A small number of subjects developed asymptomatic low titer antibodies to IL-12 or IL-15. Cellular immunogenicity following 3 and 4 vaccinations was poor, with response rates to gag of 4.9%/8.7% among vaccinees receiving gag DNA alone, 0%/11.5% among those receiving gag DNA+IL-15, and no responders among those receiving DNA+high dose (1500 ug) IL-12 DNA. However, after three doses, 44.4% (4/9) of vaccinees receiving gag DNA and intermediate dose (500 ug) of IL-12 DNA demonstrated a detectable cellular immune response.Conclusions/SignificanceThis combination of HIV gag DNA with plasmid cytokine adjuvants was well tolerated. There were minimal responses to HIV gag DNA alone, and no apparent augmentation with either IL-12 or IL-15 plasmid cytokine adjuvants. Despite the promise of DNA vaccines, newer formulations or methods of delivery will be required to increase their immunogenicity.Trial RegistrationClinicaltrials.gov NCT00115960 NCT00111605

Inoculation of human subjects with mouse monoclonal antibody results in the production of anti-idiotype antibody that reacts with the binding site of the monoclonal antibody. This reaction is hapten-inhibited, suggesting that an internal image of the antigen is produced by the anti-idiotype response. The anti-idiotype antibody isolated from sera of three patients showed significant crossreactivity. Patients who developed the anti-idiotype antibody improved clinically and had long remission from their disease. The possible presence of the internal image of cancer antigen on the human immunoglobulin molecule may change the conditions under which the immune system reacts to the tumor antigen and may open new approaches to the control of tumor growth.

Macrophages isolated from tumor-bearing patients as well as cultured human monocytes express Fc receptors that cross-react strongly with murine immunoglobulins of the G2a but only slightly or not at all with the G1, G2b, or G3 subclasses. Such macrophages in the presence of murine immunoglobulin G2a monoclonal antibodies to tumors mediated the killing of tumor cells in vitro. These data suggest that monoclonal antibodies of the G2a subclass may be useful in the immunotherapy of human cancer.

As a major cause of acute and chronic liver disease as well as hepatocellular carcinoma, hepatitis B virus (HBV) continues to pose significant health problems worldwide. Recombinant hepatitis B vaccines based on adenovirus vectors have been developed to address global needs for effective control of hepatitits B infection. Although considerable progress has been made in the construction ofrecombinant adenoviruses that express large amounts of HBV gene products, preclinical immunogenicity and efficacy testing of candidate vaccines has remained difficult due to the lack of a suitable animal model. We demonstrate here that chimpanzees are susceptible to enteric infection by human adenoviruses type 7 (Ad7) and type 4 (Ad4) following oral admiistrtion of live virus. Moreover, after sequential oral immunization with Ad7-and Ad4-vectored vaccines containing the hepatitis B surface antigen (HBsAg) gene, significant antibody responses to HBsAg (anti-HBs) were induced in two chimpanzees. After challenge with heterologous HBV, one chimpanzee was protected from acute hepatitis and the other chimpanzee experienced modified HBV-induced disease. These data demonstrate the feasibility of using orally administered recombinant adenoviruses as a general approach to vaccination.

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Recombinant adenoviruses carrying the hepatitis B virus surface antigen coding sequence in the adenovirus E3 region were constructed using DNA from either adenovirus type 5 or an adenovirus type 5 E3-region deletion mutant. Both of these recombinant adenoviruses replicated as efficiently as wild-type adenovirus in all human cells tested, including the human diploid cell strain WI-38. This indicates that insertion of the hepatitis B virus surface antigen gene into the E3 region does not significantly affect viral replication. Human cells infected with these recombinant adenoviruses secreted immunoreactive hepatitis B virus surface antigen. Since a practical small animal model for human adenoviruses was lacking, a hamster model was developed to evaluate the immunogenic potential of these recombinant adenoviruses. Upon intranasal inoculation, both wildtype adenovirus and the adenovirus E3-region deletion mutant replicated in the lungs of these animals and induced an antibody response against adenovirus. Hamsters similarly immunized with the live recombinant adenoviruses produced antibody against both adenovirus and hepatitis B virus surface antigen. (7,8). They give rise to asymptomatic intestinal adenovirus infections in humans that induce immunity against adenovirus respiratory disease. These characteristics have prompted us to develop recombinant adenoviruses that direct infected cells to produce HBsAg and thus confer immunity against both adenovirus and HBV. Vaccinia virus recombinants that direct production of HBsAg in animals (9, 10) were designed with a similar strategy in mind; however, live recombinant adenovirus vaccines provide the convenience of oral administration. In this study we describe recombinant adenoviruses that carry the HBsAg-coding sequence in the adenovirus E3 region and that direct the production of immunogenic HBsAg. Hepatitis MATERIALS AND METHODSCells and Viruses. Cell line 293 derived from human embryonic kidney (11) was used for calcium phosphate transfection as described (12). Adenovirus type 5 (Ad5) and the recombinant adenoviruses described below were grown and titrated on 293 cells as well as on A549 cells (13) derived from human lung carcinoma. These viruses were also grown on the human diploid cell strain WI-38 (14).Immunological Reagents. HBsAg was assayed using diagnostic RIA kits from Organon Teknika (Irving, TX) and from Abbott (North Chicago, IL). The levels ofantibodies directed against HBsAg were measured using a diagnostic RIA kit (AUSAB) from Abbott. Antibody levels were converted from RIA units to milliinternational units (mIU) based on an equivalence factor of 3.5 RIA units per 1 mIU. Monoclonal antibody A5C11 against HBsAg was obtained from Centocor (Malvern, PA).Metabolic Radiolabeling and Electrophoretic Analysis. A549 cells were metabolically radiolabeled using L-[35 ]cysteine at 260 p.Ci/ml (1 Ci = 37 GBq) during either the early phase (4.5-9 hr after infection) or the late phase (22.5-27 hr after infection) of infection with either AdS E3HS or AdS AE3HS...