CpG Adjuvant Research Articles

Phase 1 Study in Malaria Naïve Adults of BSAM2/Alhydrogel®+CPG 7909, a Blood Stage Vaccine against P. falciparum Malaria

A Phase 1 dose escalating study was conducted in malaria naïve adults to assess the safety, reactogenicity, and immunogenicity of the blood stage malaria vaccine BSAM2/Alhydrogel®+ CPG 7909. BSAM2 is a combination of the FVO and 3D7 alleles of recombinant AMA1 and MSP142, with equal amounts by weight of each of the four proteins mixed, bound to Alhydrogel®, and administered with the adjuvant CPG 7909. Thirty (30) volunteers were enrolled in two dose groups, with 15 volunteers receiving up to three doses of 40 µg total protein at Days 0, 56, and 180, and 15 volunteers receiving up to three doses of 160 µg protein on the same schedule. Most related adverse events were mild or moderate, but 4 volunteers experienced severe systemic reactions and two were withdrawn from vaccinations due to adverse events. Geometric mean antibody levels after two vaccinations with the high dose formulation were 136 µg/ml for AMA1 and 78 µg/ml for MSP142. Antibody responses were not significantly different in the high dose versus low dose groups and did not further increase after third vaccination. In vitro growth inhibition was demonstrated and was closely correlated with anti-AMA1 antibody responses. A Phase 1b trial in malaria-exposed adults is being conducted.Trial RegistrationClinicaltrials.gov NCT00889616

A DNA Nanostructure Platform for Directed Assembly of Synthetic Vaccines

Safe and effective vaccines offer the best intervention for disease control. One strategy to maximize vaccine immunogenicity without compromising safety is to rationally design molecular complexes that mimic the natural structure of immunogenic microbes but without the disease-causing components. Here we use highly programmable DNA nanostructures as platforms to assemble a model antigen and CpG adjuvants together into nanoscale complexes with precise control of the valency and spatial arrangement of each element. Our results from immunized mice show that compared to a mixture of antigen and CpG molecules, the assembled antigen-adjuvant-DNA complexes induce strong and long-lasting antibody responses against the antigen without stimulating a reaction to the DNA nanostructure itself. This result demonstrates the potential of DNA nanostructures to serve as general platforms for the rational design and construction of a variety of vaccines.

Immunization With WT1-derived Peptides by Tattooing Inhibits the Growth of TRAMP-C2 Prostate Tumor in Mice

The expression of the transcription factor encoded by the Wilms tumor gene 1 (WT1) is associated with a variety of human cancers. WT1 protein has been reported to serve as a target antigen for tumor-specific immune responses. We observed that the immunization of mice with peptide vaccines derived from WT1 in a mixture with the CpG adjuvant (ODN 1826) by tattoo administration was superior to subcutaneous delivery of the peptides in combination with CpG formulated with the mineral oil adjuvant or a DNA vaccine or a recombinant vaccinia virus vaccine expressing the truncated WT1 protein. Tattooing with the WT1122-140 and WT1126-134 peptide elicited the response of WT1-specific interferon-γ-producing T cells. Peptide vaccine administered with a tattoo device had an antitumor effect on the growth of the prostate tumor cell line TRAMP-C2, provided that the transforming growth factor-β produced by tumor cells was neutralized by anti-TGFβ monoclonal antibody. The treatment of the tumor-bearing mice with 5-azadeoxycytidine or poly IC did not work in synergy with the peptide vaccine.

Glycoprotein G of Herpes Simplex Virus 2 as a Novel Vaccine Antigen for Immunity to Genital and Neurological Disease

The envelope glycoproteins of herpes simplex virus 1 (HSV-1) and HSV-2, with the exception of glycoprotein G, elicit cross-reactive B- and T-cell responses. Human vaccine trials, using the cross-reactive glycoproteins B and D, have shown no protection against genital HSV-2 infection or disease. In this study, the mature form of glycoprotein G (mgG-2) of HSV-2 was used for immunization of mice, either alone or in combination with adjuvant CpG, followed by an intravaginal challenge with a lethal dose of a fully virulent HSV-2 strain. Mice immunized with mgG-2 plus CpG showed low disease scores and a significantly higher survival rate (73%) than mice immunized with mgG-2 alone (20%) or controls (0%). Accordingly, limited numbers of infectious HSV-2 particles were detected in the spinal cord of mice immunized with mgG-2 plus CpG. The observed protection was associated with a gamma interferon (IFN-γ) response by splenic CD4(+) T cells upon antigen restimulation in vitro and in vaginal washes 1 day postinfection. The majority of sera collected from mice immunized with mgG-2 plus CpG showed macrophage-mediated antibody-dependent cellular cytotoxicity and antibody-dependent complement-mediated cytolysis, while no neutralization activity was observed. In conclusion, we have shown that immunization with the type-specific mgG-2 protein in combination with CpG could elicit protective immunity against an otherwise lethal vaginal HSV-2 challenge. The mgG-2 protein may therefore constitute a promising HSV-2 vaccine antigen to be considered for future human trials.

Risk Factors for Pneumococcal Nasopharyngeal Colonization Before and After Pneumococcal Conjugate Vaccination in Persons with HIV: Brief Report

HIV-infected individuals have excess rates of invasive pneumococcal disease. We investigated risk factors for nasopharyngeal pneumococcal colonization at baseline and after 9 months in 96 HIV patients immunized twice with 7- valent pneumococcal conjugate vaccine ±1mg CPG 7909. In total, 22 patients (23%) were colonized, 11 at baseline only, four at both baseline and 9 months, and seven at 9 months only. Compared to non-colonized patients, more colonized patients were smokers, had lower CD4+ nadir and had an AIDS-diagnosis. Immunization, antiretroviral treatment and the CPG adjuvant had no impact on colonization. These results suggest preventive strategies in addition to pneumococcal immunization.

The Role of MyD88 in the Adjuvant Activity of Neisseria meningitidis PorB (53.5)

Abstract Adjuvants enhance the response to poorly immunogenic antigens in vaccines. Our laboratory has shown by ELISA that Neisseria meningitidis outer membrane protein PorB acts as an adjuvant by eliciting a greater serum concentration of antigen-specific IgG when compared to immunization with antigen alone, with Ovalbumin as the antigen. PorB is a TLR2 ligand and signals through the adaptor protein MyD88. We compared the adjuvant effect of PorB to other adjuvants (Alum, MPL & CpG) in WT & MyD88 KO mice. PorB adjuvant activity was ablated in MyD88 KO mice and consistent with previous investigations: MPL & CpG adjuvant activity was also MyD88-dependent while Alum acted independently of MyD88. In addition, we previously observed PorB had residual adjuvant activity in TLR2 KO mice. One hypothesis was that PorB could stimulate the Nalp3 inflammasome and induce IL-1β production without a second signal e.g. ATP. Therefore, bone marrow-derived macrophages were stimulated with PorB ± ATP. The IL-1β production was analyzed by ELISA and compared to IL-1β production from stimulation with other TLR ligands. We found that PorB required ATP in order to sufficiently produce IL-1β, disproving our hypothesis. Overall, our results show an importance for MyD88 in both the adjuvant pathway of PorB & other TLR ligand-based adjuvants. One future direction for this work is MyD88 deletion in an antigen-presenting cell-specific manner to examine the role of each cell type in the adjuvant activity of PorB.

Chicken anemia virus (CAV) induces thymic lymphoid cell disorders and the improvement of CAV vaccine efficacy by fusing VP1/VP2 proteins with CpG adjuvant

Chicken anemia virus (CAV) induces thymic lymphoid cell disorders and the improvement of CAV vaccine efficacy by fusing VP1/VP2 proteins with CpG adjuvant

TACI Expression is Low Both in Human and Mouse Newborns

To the Editor: We read with high interest the recent article titled ‘Age-matched reference values for B-cell subpopulation and CVID classifications in children’ by Schatorjé and colleagues [1]. The authors studied the expression of TACI and BAFF-R in both newborn and infant age groups starting from cord blood. In this sudy, they reported that while the percentage of BAFF-R+ B cells do not change during the first year of life, TACI+ B cell percentage showed an age-dependent increase. In accordance with these human studies by Schatorjé and colleagues, we found that murine newborn B cells also had low percentage of TACI+ B cells while BAFF-R and BCMA expressing B cell percentages were comparable to those of adult mice [2]. We have analyzed the expression and function of BAFF system molecules in newborn mice because newborns of mice and humans share several aspects of their hematopoietic development and function. For example both human and mice newborns do not respond to T cell-independent type 2 (TI-2) antigens such as bacterial polysaccharide vaccines [3]. In addition to low TACI expression in newborn mice [2], we also showed that low B cell TACI expression correlated with impaired immunoglobulin secretion, plasma cell generation and proliferation of B cells in response to either BAFF or APRIL stimulation in this age group. These results provided a rational explanation for the weak immunogenicity of TI-2 antigens in newborns because we could render the TI-2 antigen NP-Ficoll immunogenic in newborns by using the adjuvant CpG that increases TACI expression [4]. Finally as with CVID patients with TACI mutations, we found that BAFF levels were increased in newborn mice and in TACI knock-out mice, further supporting a role for TACI in modulating BAFF expression. Thus, the demonstration of low TACI expression in human infants reported by Schatorjé and colleagues signifies yet another similarity between mice and human immune system and underscores the relevance of studies on the BAFF system components conducted in mice as organismal models.

Antigen depot is not required for alum adjuvanticity

Alum adjuvants have been in continuous clinical use for more than 80 yr. While the prevailing theory has been that depot formation and the associated slow release of antigen and/or inflammation are responsible for alum enhancement of antigen presentation and subsequent T- and B-cell responses, this has never been formally proven. To examine antigen persistence, we used the chimeric fluorescent protein EαGFP, which allows assessment of antigen presentation in situ, using the Y-Ae antibody. We demonstrate that alum and/or CpG adjuvants induced similar uptake of antigen, and in all cases, GFP signal did not persist beyond 24 h in draining lymph node antigen-presenting cells. Antigen presentation was first detectable on B cells within 6–12 h of antigen administration, followed by conventional dendritic cells (DCs) at 12–24 h, then finally plasmacytoid DCs at 48 h or later. Again, alum and/or CpG adjuvants did not have an effect on the magnitude or sequence of this response; furthermore, they induced similar antigen-specific T-cell activation in vivo. Notably, removal of the injection site and associated alum depot, as early as 2 h after administration, had no appreciable effect on antigen-specific T- and B-cell responses. This study clearly rules out a role for depot formation in alum adjuvant activity.—Hutchison, S., Benson, R. A., Gibson, V. B., Pollock, A. H., Garside, P., Brewer, J. M. Antigen depot is not required for alum adjuvanticity.

Single and Combination Herpes Simplex Virus Type 2 Glycoprotein Vaccines Adjuvanted with CpG Oligodeoxynucleotides or Monophosphoryl Lipid A Exhibit Differential Immunity That Is Not Correlated to Protection in Animal Models

Despite several attempts to develop an effective prophylactic vaccine for HSV-2, all have failed to show efficacy in the clinic. The most recent of these failures was the GlaxoSmithKline (GSK) subunit vaccine based on the glycoprotein gD with the adjuvant monophosphoryl lipid A (MPL). In a phase 3 clinical trial, this vaccine failed to protect from HSV-2 disease, even though good neutralizing antibody responses were elicited. We aimed to develop a superior, novel HSV-2 vaccine containing either gD or gB alone or in combination, together with the potent adjuvant CpG oligodeoxynucleotides (CPG). The immunogenic properties of these vaccines were compared in mice. We show that gB/CPG/alum elicited a neutralizing antibody response similar to that elicited by gD/CPG/alum vaccine but a significantly greater gamma interferon (IFN-γ) T cell response. Furthermore, the combined gB-gD/CPG/alum vaccine elicited significantly greater neutralizing antibody and T cell responses than gD/MPL/alum. The efficacies of these candidate vaccines were compared in the mouse and guinea pig disease models, including a novel male guinea pig genital disease model. These studies demonstrated that increased immune response did not correlate to improved protection. First, despite a lower IFN-γ T cell response, the gD/CPG/alum vaccine was more effective than gB/CPG/alum in mice. Furthermore, the gB-gD/CPG/alum vaccine was no more effective than gD/MPL/alum in mice or male guinea pigs. We conclude that difficulties in correlating immune responses to efficacy in animal models will act as a deterrent to researchers attempting to develop effective HSV vaccines.

Murine Polyomavirus Virus-Like Particles Carrying Full-Length Human PSA Protect BALB/c Mice from Outgrowth of a PSA Expressing Tumor

Virus-like particles (VLPs) consist of capsid proteins from viruses and have been shown to be usable as carriers of protein and peptide antigens for immune therapy. In this study, we have produced and assayed murine polyomavirus (MPyV) VLPs carrying the entire human Prostate Specific Antigen (PSA) (PSA-MPyVLPs) for their potential use for immune therapy in a mouse model system. BALB/c mice immunized with PSA-MPyVLPs were only marginally protected against outgrowth of a PSA-expressing tumor. To improve protection, PSA-MPyVLPs were co-injected with adjuvant CpG, either alone or loaded onto murine dendritic cells (DCs). Immunization with PSA-MPyVLPs loaded onto DCs in the presence of CpG was shown to efficiently protect mice from tumor outgrowth. In addition, cellular and humoral immune responses after immunization were examined. PSA-specific CD4+ and CD8+ cells were demonstrated, but no PSA-specific IgG antibodies. Vaccination with DCs loaded with PSA-MPyVLPs induced an eight-fold lower titre of anti-VLP antibodies than vaccination with PSA-MPyVLPs alone. In conclusion, immunization of BALB/c mice with PSA-MPyVLPs, loaded onto DCs and co-injected with CpG, induces an efficient PSA-specific tumor protective immune response, including both CD4+ and CD8+ cells with a low induction of anti-VLP antibodies.

A Neonatal Fc Receptor-Targeted Mucosal Vaccine Strategy Effectively Induces HIV-1 Antigen-Specific Immunity to Genital Infection

Strategies to prevent the sexual transmission of HIV include vaccines that elicit durable, protective mucosal immune responses. A key to effective mucosal immunity is the capacity for antigens administered locally to cross epithelial barriers. Given the role of neonatal Fc receptor (FcRn) in transferring IgG across polarized epithelial cells which line mucosal surfaces, FcRn might be useful for delivering HIV vaccine antigens across mucosal epithelial barriers to the underlying antigen-presenting cells. Chimeric proteins composed of HIV Gag (p24) fused to the Fc region of IgG (Gag-Fc) bind efficiently to airway mucosa and are transported across this epithelial surface. Mice immunized intranasally with Gag-Fc plus CpG adjuvant developed local and systemic immunity, including durable B and T cell memory. Gag-specific immunity was sufficiently potent to protect against an intravaginal challenge with recombinant vaccinia virus expressing the HIV Gag protein. Intranasal administration of a Gag-Fc/CpG vaccine protected at a distal mucosal site. Our data suggest that targeting of FcRn with chimeric immunogens may be an important strategy for mucosal immunization and should be considered a new approach for preventive HIV vaccines.

Nanoparticle conjugation and pulmonary delivery enhance the protective efficacy of Ag85B and CpG against tuberculosis

Vaccines that drive robust T-cell immunity against Mycobacterium tuberculosis ( Mtb) are needed both for prophylactic and therapeutic purposes. We have recently developed a synthetic vaccine delivery platform with Pluronic-stabilized polypropylene sulfide nanoparticles (NPs), which target lymphoid tissues by their small size (∼30 nm) and which activate the complement cascade by their surface chemistry. Here we conjugated the tuberculosis antigen Ag85B to the NPs (NP-Ag85B) and compared their efficacy in eliciting relevant immune responses in mice after intradermal or pulmonary administration. Pulmonary administration of NP-Ag85B with the adjuvant CpG led to enhanced induction of antigen-specific polyfunctional Th1 responses in the spleen, the lung and lung-draining lymph nodes as compared to soluble Ag85B with CpG and to the intradermally-delivered formulations. Mucosal and systemic Th17 responses were also observed with this adjuvanted NP formulation and vaccination route, especially in the lung. We then evaluated protection induced by the adjuvanted NP formulation following a Mtb aerosol challenge and found that vaccination with NP-Ag85B and CpG via the pulmonary route displayed a substantial reduction of the lung bacterial burden, both compared to soluble Ag85B with CpG and to the corresponding intradermally delivered formulations. These findings highlight the potential of administrating NP-based formulations by the pulmonary route for TB vaccination.

DNA VACCINATION OF BISON TO BRUCELLAR ANTIGENS ELICITS ELEVATED ANTIBODY AND IFN-γ RESPONSES

Brucella abortus remains a threat to the health and well-being of livestock in states bordering the Greater Yellowstone Area. During the past several years, cohabitation of infected wildlife with cattle has jeopardized the brucellosis-free status of Idaho, USA; Wyoming, USA; and Montana, USA. Current livestock B. abortus vaccines have not proven to be efficacious in bison (Bison bison) or elk (Cervus elaphus nelsoni). One problem with the lack of vaccine efficacy may stem from the failure to understand wildlife immune responses to vaccines. In an attempt to understand their immune responses, bison were vaccinated with eukaryotic DNA expression vectors encoding the Brucella periplasmic protein, bp26, and the chaperone protein, trigger factor (TF). These DNA vaccines have previously been shown to be protective against Brucella infection in mice. Bison were immunized intramuscularly at weeks 0, 2, and 4 with bp26 and TF DNA vaccines plus CpG adjuvant or empty vector (control) plus CpG. Blood samples were collected before vaccination and at 8, 10, and 12 wk after primary vaccination. The results showed that bison immunized with bp26 and TF DNA vaccines developed enhanced antibody, proliferative T cell, and interferon-gamma (IFN-γ) responses upon in vitro restimulation with purified recombinant bp26 or TF antigens, unlike bison immunized with empty vector. Flow cytometric analysis revealed that the percentages of CD4(+) and CD8(+) T lymphocytes from the DNA-vaccinated groups were significantly greater than they were for those bison given empty vector. These data suggest that DNA vaccination of bison may elicit strong cellular immune responses and serve as an alternative for vaccination of bison for brucellosis.

Antibody against extracellular vaccinia virus (EV) protects mice through complement and Fc receptors.

Protein-based subunit smallpox vaccines have shown their potential as effective alternatives to live virus vaccines in animal model challenge studies. We vaccinated mice with combinations of three different vaccinia virus (VACV) proteins (A33, B5, L1) and examined how the combined antibody responses to these proteins cooperate to effectively neutralize the extracellular virus (EV) infectious form of VACV. Antibodies against these targets were generated in the presence or absence of CpG adjuvant so that Th1-biased antibody responses could be compared to Th2-biased responses to the proteins with aluminum hydroxide alone, specifically with interest in looking at the ability of anti-B5 and anti-A33 polyclonal antibodies (pAb) to utilize complement-mediated neutralization in vitro. We found that neutralization of EV by anti-A33 or anti-B5 pAb can be enhanced in the presence of complement if Th1-biased antibody (IgG2a) is generated. Mechanistic differences found for complement-mediated neutralization showed that anti-A33 antibodies likely result in virolysis, while anti-B5 antibodies with complement can neutralize by opsonization (coating). In vivo studies found that mice lacking the C3 protein of complement were less protected than wild-type mice after passive transfer of anti-B5 pAb or vaccination with B5. Passive transfer of anti-B5 pAb or monoclonal antibody into mice lacking Fc receptors (FcRs) found that FcRs were also important in mediating protection. These results demonstrate that both complement and FcRs are important effector mechanisms for antibody-mediated protection from VACV challenge in mice.

Marked enhancement of the immune response to BioThrax® (Anthrax Vaccine Adsorbed) by the TLR9 agonist CPG 7909 in healthy volunteers

Immunization with BioThrax® (Anthrax Vaccine Adsorbed) is a safe and effective means of preventing anthrax. Animal studies have demonstrated that the addition of CpG DNA adjuvants to BioThrax can markedly increase the immunogenicity of the vaccine, increasing both serum anti-protective antigen (PA) antibody and anthrax toxin-neutralizing antibody (TNA) concentrations. The immune response to CpG-adjuvanted BioThrax in animals was not only stronger, but was also more rapid and led to higher levels of protection in spore challenge models. The B-class CpG DNA adjuvant CPG 7909, a 24-base synthetic, single-strand oligodeoxynucleotide, was evaluated for its safety profile and adjuvant properties in a Phase 1 clinical trial. A double-blind study was performed in which 69 healthy subjects, age 18–45 years, were randomized to receive three doses of either: (1) BioThrax alone, (2) 1mg of CPG 7909 alone or (3) BioThrax plus 1mg of CPG 7909, all given intramuscularly on study days 0, 14 and 28. Subjects were monitored for IgG to PA by ELISA and for TNA titers through study day 56 and for safety through month 6. CPG 7909 increased the antibody response by 6–8-fold at peak, and accelerated the response by 3 weeks compared to the response seen in subjects vaccinated with BioThrax alone. No serious adverse events related to study agents were reported, and the combination was considered to be reasonably well tolerated. The marked acceleration and enhancement of the immune response seen by combining BioThrax and CPG 7909 offers the potential to shorten the course of immunization and reduce the time to protection, and may be particularly useful in the setting of post-exposure prophylaxis.

Induction of protection against vaginal shedding and infertility by a recombinant Chlamydia vaccine

A vaccine formulated with the Chlamydia muridarum recombinant major outer membrane protein, plus the adjuvants CpG and Montanide, was tested for its ability to protect BALB/c mice against a vaginal challenge. Mice were immunized by mucosal [intravaginal (i.vag.) plus colonic (col.), or intranasal (i.n.) plus sublingual (s.l.)], or systemic [intramuscular (i.m.) plus subcutaneous (s.c.)] routes, and a combination of mucosal priming and systemic boosting routes. A negative control group was vaccinated with the Neisseria gonorrhoeae porin B (Ng-rPorB) and a positive control group was inoculated in the nares with live Chlamydia. The strongest Chlamydia-specific humoral and cell-mediated immune responses were observed in the groups immunized by a combination of mucosal and systemic routes. Following the vaginal challenge, groups immunized using mucosal priming followed by systemic immunization had a significant decrease in the number of mice with positive vaginal cultures. For example, of the mice immunized i.n./s.l.+i.m./s.c., 24% had positive cultures during the six weeks of the experiment versus 69% for the negative control group immunized with Ng-rPorB (P<0.05). Similarly, the groups of mice primed by the mucosal routes and boosted by the systemic routes had significantly less IFU in the vaginal cultures when compared to the Ng-rPorB animals (P<0.05). These combination groups were also protected against infertility. The two groups had fertility rates of 100% (i.n./s.l.+i.m./s.c.) and 81% (i.vag./col.+i.m./s.c.) equivalent to the positive-control group immunized with live Chlamydia (100% fertility; P>0.05). These results show the importance of the schedule and routes of vaccination and represent the first study to show protection against infertility by a Chlamydia recombinant subunit vaccine.

Sublingual vaccination with sonicated Salmonella proteins and mucosal adjuvant induces mucosal and systemic immunity and protects mice from lethal enteritis

Salmonella enteritidis is one of the most common pathogens of enteritis. Most experimental vaccines against Salmonella infection have been applied through injections. This is a new trial to explore the effect of sublingual administration of Salmonella vaccines on systemic and mucosal immunity. Adult BALB/c mice were sublingually vaccinated with sonicated Salmonella proteins (SSP) alone, or plus adjuvant CpG DNA (CpG) or cholera toxin (CT). They were boosted 2 weeks later. Saliva specific secretory IgA (SIgA) antibody responses were significantly stimulated in the mice vaccinated with SSP only or together with CpG or CT. Whereas the mice sublingually vaccinated with SSP and CpG had higher spleen cell IFN-γ production and serum specific IgG2a antibody responses, those receiving SSP and CT showed enhanced spleen cell IL-4, IL-5 and IL-6 production, and serum specific IgG1 antibody responses. After oral challenge with live S. enteritidis, the same strain of the source of SSP, immune protection in those sublingually vaccinated with SSP and CpG or CT was found to prevent intestinal necrosis and to render a higher survival rate. In conclusion, sublingual vaccination together with mucosal adjuvant CpG or CT is a simple but effective way against enteric bacterial pathogens.

Efficient mucosal vaccination mediated by the neonatal Fc receptor (155.9)

Abstract Almost all infectious diseases are initiated at mucosal surfaces, yet intramuscular or subcutaneous vaccination usually provides only minimal protection at sites of infection owing to suboptimal activation of the mucosal immune system. The neonatal Fc receptor (FcRn) mediates the transport of IgG across polarized epithelial cells lining mucosal surfaces. We mimicked this process by fusing a model antigen, herpes simplex virus type-2 (HSV-2) glycoprotein gD, to an IgG Fc fragment. Intranasal immunization, together with the adjuvant CpG, completely protected wild-type, but not FcRn knockout, mice after intravaginal challenge with virulent HSV-2 186. This immunization strategy induced efficient mucosal and systemic antibody, B- and T-cell immune responses, with stable protection for at least 6 months after vaccination in most of the immunized animals. The FcRn-IgG transcellular transport pathway may provide a general delivery route for subunit vaccines against many mucosal pathogens.

Efficient In vivo Priming by Vaccination with Recombinant NY-ESO-1 Protein and CpG in Antigen Naïve Prostate Cancer Patients

NY-ESO-1, one of the most immunogenic tumor antigens, is expressed in 15% to 25% of metastatic prostate cancers. The immunological and clinical effects of vaccination with recombinant NY-ESO-1 protein combined with CpG as adjuvant were evaluated. In a phase I clinical study, patients with advanced prostate cancer were vaccinated with recombinant NY-ESO-1 protein (100 μg) mixed with CpG 7909 (2.5 mg) every 3 weeks intradermally for 4 doses. Objectives of the study were the safety of the vaccine and changes of specific humoral and cellular immunological responses to NY-ESO-1 in relation to detectable NY-ESO-1 expression in the individual tumor. All 12 baseline sero-negative patients developed high-titer NY-ESO-1 antibody responses. B-cell epitope mapping identified NY-ESO-1 p91-110 to be recognized most frequently by vaccine-induced antibodies. Two patients developed significant antibody titers against the adjuvant CpG. NY-ESO-1-specific CD4+ and/or CD8+ T-cell responses were induced in 9 patients (69%). Five of these 9 patients did not express NY-ESO-1 in the autologous tumor. Postvaccine CD8+ T-cell clones recognized and lyzed HLA-matched tumor cell lines in an antigen-specific manner. Our data provide clear evidence for the capacity of NY-ESO-1 protein/CpG vaccine to induce integrated antigen-specific immune responses in vivo and to efficiently prime CD8+ T-cell responses in NY-ESO-1 antigen-negative patients. Our results may also support further clinical vaccination protocols with NY-ESO-1 protein not only focused on the treatment of existing cancer, but also to prevent further development of NY-ESO-1 positive cancers in vivo.