A dose-dependent plasma signature of the safety and immunogenicity of the rVSV-Ebola vaccine in Europe and Africa

The 2014-2015 Ebola epidemic affected several African countries, claiming more than 11,000 lives and leaving thousands with ongoing sequelae. Safe and effective vaccines could prevent or limit future outbreaks. The recombinant vesicular stomatitis virus-vectored Zaire Ebola (rVSV-ZEBOV) vaccine has shown marked immunogenicity and efficacy in humans but is reactogenic at higher doses. To understand its effects, we examined plasma samples from 115 healthy volunteers from Geneva who received low-dose (LD) or high-dose (HD) vaccine or placebo. Fifteen plasma chemokines/cytokines were assessed at baseline and on days 1, 2 to 3, and 7 after injection. Significant increases in monocyte-mediated MCP-1/CCL2, MIP-1β/CCL4, IL-6, TNF-α, IL-1Ra, and IL-10 occurred on day 1. A signature explaining 68% of cytokine/chemokine vaccine-response variability was identified. Its score was higher in HD versus LD vaccinees and was associated positively with vaccine viremia and negatively with cytopenia. It was higher in vaccinees with injection-site pain, fever, myalgia, chills, and headache; higher scores reflected increasing severity. In contrast, HD vaccinees who subsequently developed arthritis had lower day 1 scores than other HD vaccinees. Vaccine dose did not influence the signature despite its influence on specific outcomes. The Geneva-derived signature associated strongly (ρ = 0.97) with that of a cohort of 75 vaccinees from a parallel trial in Lambaréné, Gabon. Its score in Geneva HD vaccinees with subsequent arthritis was significantly lower than that in Lambaréné HD vaccinees, none of whom experienced arthritis. This signature, which reveals monocytes' critical role in rVSV-ZEBOV immunogenicity and safety across doses and continents, should prove useful in assessments of other vaccines.

Nasal Immunization Confers High Avidity Neutralizing Antibody Response and Immunity to Primary and Recurrent Genital Herpes in Guinea Pigs

Genital herpes is one of the most prevalent sexually transmitted infections in both the developing and developed world. Following infection, individuals experience life-long latency associated with sporadic ulcerative outbreaks. Despite many efforts, no vaccine has yet been licensed for human use. Herein, we demonstrated that nasal immunization with an adjuvanted HSV-2 gD envelope protein mounts significant protection to primary infection as well as the establishment of latency and recurrent genital herpes in guinea pigs. Nasal immunization was shown to elicit specific T cell proliferative and IFN-γ responses as well as systemic and vaginal gD-specific IgG antibody (Ab) responses. Furthermore, systemic IgG Abs displayed potent HSV-2 neutralizing properties and high avidity. By employing a competitive surface plasmon resonance (SPR) analysis combined with a battery of known gD-specific neutralizing monoclonal Abs (MAbs), we showed that nasal immunization generated IgG Abs directed to two major discontinuous neutralizing epitopes of gD. These results highlight the potential of nasal immunization with an adjuvanted HSV-2 envelope protein for induction of protective immunity to primary and recurrent genital herpes.

Comparative Systems Analyses Reveal Molecular Signatures of Clinically tested Vaccine Adjuvants

A better understanding of the mechanisms of action of human adjuvants could inform a rational development of next generation vaccines for human use. Here, we exploited a genome wide transcriptomics analysis combined with a systems biology approach to determine the molecular signatures induced by four clinically tested vaccine adjuvants, namely CAF01, IC31, GLA-SE and Alum in mice. We report signature molecules, pathways, gene modules and networks, which are shared by or otherwise exclusive to these clinical-grade adjuvants in whole blood and draining lymph nodes of mice. Intriguingly, co-expression analysis revealed blood gene modules highly enriched for molecules with documented roles in T follicular helper (TFH) and germinal center (GC) responses. We could show that all adjuvants enhanced, although with different magnitude and kinetics, TFH and GC B cell responses in draining lymph nodes. These results represent, to our knowledge, the first comparative systems analysis of clinically tested vaccine adjuvants that may provide new insights into the mechanisms of action of human adjuvants.

Ebola vaccine R&D: Filling the knowledge gaps

With an emphasis on systems analyses, the VSV-EBOVAC project harnesses state-of-the-art technologies that illuminate mechanisms behind the observed immunogenicity and reactogenicity of the rVSV-ZEBOV vaccine and ensures that such information is shared among stakeholders.

Intradermal immunisation using the TLR3-ligand Poly (I:C) as adjuvant induces mucosal antibody responses and protects against genital HSV-2 infection

Development of vaccines able to induce mucosal immunity in the genital and gastrointestinal tracts is a major challenge to counter sexually transmitted pathogens such as HIV-1 and HSV-2. Herein, we showed that intradermal (ID) immunisation with sub-unit vaccine antigens (i.e., HIV-1 gp140 and HSV-2 gD) delivered with Poly(I:C) or CpG1668 as adjuvant induces long-lasting virus-specific immunoglobulin (Ig)-G and IgA antibodies in the vagina and feces. Poly(I:C)-supplemented sub-unit viral vaccines caused minimal skin reactogenicity at variance to those containing CpG1668, promoted a delayed-type hypersensitivity (DTH) to the vaccine and protected mice from genital and neurological symptoms after a lethal vaginal HSV-2 challenge. Interestingly, Poly(I:C_12U) (Ampligen), a Poly(I:C) structural analogue that binds to TLR3 but not MDA-5, promoted robust mucosal and systemic IgG antibodies, a weak skin DTH to the vaccine but not IgA responses and failed to confer protection against HSV-2 infection. Moreover, Poly(I:C) was far superior to Poly(I:C_12U) at inducing prompt and robust upregulation of IFNß transcripts in lymph nodes draining the injection site. These data illustrate that ID vaccination with glycoproteins and Poly(I:C) as adjuvant promotes long-lasting mucosal immunity and protection from genital HSV-2 infection, with an acceptable skin reactogenicity profile. The ID route thus appears to be an unexpected inductive site for mucosal immunity and anti-viral protection suitable for sub-unit vaccines. This works further highlights that TLR3/MDA5 agonists such as Poly(I:C) may be valuable adjuvants for ID vaccination against sexually transmitted diseases.

Different human vaccine adjuvants promote distinct antigen-independent immunological signatures tailored to different pathogens

The majority of vaccine candidates in clinical development are highly purified proteins and peptides relying on adjuvants to enhance and/or direct immune responses. Despite the acknowledged need for novel adjuvants, there are still very few adjuvants in licensed human vaccines. A vast number of adjuvants have been tested pre-clinically using different experimental conditions, rendering it impossible to directly compare their activity. We performed a head-to-head comparison of five different adjuvants Alum, MF59®, GLA-SE, IC31® and CAF01 in mice and combined these with antigens from M. tuberculosis, influenza, and chlamydia to test immune-profiles and efficacy in infection models using standardized protocols. Regardless of antigen, each adjuvant had a unique immunological signature suggesting that the adjuvants have potential for different disease targets. Alum increased antibody titers; MF59® induced strong antibody and IL-5 responses; GLA-SE induced antibodies and Th1; CAF01 showed a mixed Th1/Th17 profile and IC31® induced strong Th1 responses. MF59® and GLA-SE were strong inducers of influenza HI titers while CAF01, GLA-SE and IC31® enhanced protection to TB and chlamydia. Importantly, this is the first extensive attempt to categorize clinical-grade adjuvants based on their immune profiles and protective efficacy to inform a rational development of next generation vaccines for human use.

Molecular signatures of vaccine adjuvants

Mass vaccination has saved millions of human lives and improved the quality of life in both developing and developed countries. The emergence of new pathogens and inadequate protection conferred by some of the existing vaccines such as vaccines for tuberculosis, influenza and pertussis especially in certain age groups have resulted in a move from empirically developed vaccines toward more pathogen tailored and rationally engineered vaccines. A deeper understanding of the interaction of innate and adaptive immunity at molecular level enables the development of vaccines that selectively target certain type of immune responses without excessive reactogenicity. Adjuvants constitute an imperative element of modern vaccines. Although a variety of candidate adjuvants have been evaluated in the past few decades, only a limited number of vaccine adjuvants are currently available for human use. A better understanding of the mode of action of adjuvants is pivotal to harness the potential of existing and new adjuvants in shaping a desired immune response. Recent advancement in systems biology powered by the emerging cutting edge omics technology has led to the identification of molecular signatures rapidly induced after vaccination in the blood that correlate and predict a later protective immune response or vaccine safety. This can pave ways to prospectively determine the potency and safety of vaccines and adjuvants. This review is intended to highlight the importance of big data analysis in advancing our understanding of the mechanisms of actions of adjuvants to inform rational development of future human vaccines.

Plant-based vaccines: novel and low-cost possible route for Mediterranean innovative vaccination strategies

A plant bioreactor has enormous capability as a system that supports many biological activities, that is, production of plant bodies, virus-like particles (VLPs), and vaccines. Foreign gene expression is an efficient mechanism for getting protein vaccines against different human viral and nonviral diseases. Plants make it easy to deal with safe, inexpensive, and provide trouble-free storage. The broad spectrum of safe gene promoters is being used to avoid risk assessments. Engineered virus-based vectors have no side effect. The process can be manipulated as follows: (a) retrieve and select gene encoding, use an antigenic protein from GenBank and/or from a viral-genome sequence, (b) design and construct hybrid-virus vectors (viral vector with a gene of interest) eventually flanked by plant-specific genetic regulatory elements for constitutive expression for obtaining chimeric virus, (c) gene transformation and/or transfection, for transient expression, into a plant-host model, that is, tobacco, to get protocols processed positively, and then moving into edible host plants, (d) confirmation of protein expression by bioassay, PCR-associated tests (RT-PCR), Northern and Western blotting analysis, and serological assay (ELISA), (e) expression for adjuvant recombinant protein seeking better antigenicity, (f) extraction and purification of expressed protein for identification and dosing, (g) antigenicity capability evaluated using parental or oral delivery in animal models (mice and/or rabbit immunization), and (h) growing of construct-treated edible crops in protective green houses. Some successful cases of heterologous gene-expressed protein, as edible vaccine, are being discussed, that is, hepatitis C virus (HCV). R9 mimotope, also named hypervariable region 1 (HVR1), was derived from the HVR1 of HCV. It was used as a potential neutralizing epitope of HCV. The mimotope was expressed using cucumber mosaic virus coat protein (CP), alfalfa mosaic virus CP P3/RNA3, and tobacco mosaic virus (TMV) CP-tobacco mild green mosaic virus (TMGMV) CP as expression vectors into tobacco plants. Expressed recombinant protein has not only been confirmed as a therapeutic but also as a diagnostic tool. Herpes simplex virus 2 (HSV-2), HSV-2 gD, and HSV-2 VP16 subunits were transfected into tobacco plants, using TMV CP-TMGMV CP expression vectors.

Polyethyleneimine is a potent mucosal adjuvant for viral glycoprotein antigens

Protection against mucosally transmitted infections probably requires immunity at the site of pathogen entry, yet there are no mucosal adjuvant formulations licensed for human use. Polyethyleneimine (PEI) represents a family of organic polycations used as nucleic acid transfection reagents in vitro and DNA vaccine delivery vehicles in vivo. Here we show that diverse PEI forms have potent mucosal adjuvant activity for viral subunit glycoprotein antigens. A single intranasal administration of influenza hemagglutinin or herpes simplex virus type-2 (HSV-2) glycoprotein D with PEI elicited robust antibody-mediated protection from an otherwise lethal infection, and was superior to existing experimental mucosal adjuvants. PEI formed nanoscale complexes with antigen, which were taken up by antigen-presenting cells in vitro and in vivo, promoted dendritic cell trafficking to draining lymph nodes and induced non-proinflammatory cytokine responses. PEI adjuvanticity required release of host double-stranded DNA that triggered Irf3-dependent signaling. PEI therefore merits further investigation as a mucosal adjuvant for human use.

Conference Scene: Recent advancements in immunopotentiators for modern vaccines

Vaccines have proved to be the most successful preventive measure against a variety of infectious diseases. Owing to the potential safety concerns associated with the use of live-attenuated or killed pathogens, there is currently a drive to discover defined subunits of pathogens or recombinant molecules for new vaccines. The development of safe and potent vaccine adjuvants with the ability to enhance and direct broad and durable immune responses to these otherwise poorly immunogenic antigens is hence a top priority. The 4th International Conference on Immunopotentiators in Modern Vaccines, held in Porto, Portugal, 6–8 April 2011, offered an international forum for reviewing the current status of research and development, as well as application of novel immunopotentiators and vaccine adjuvants to vaccines. During the 3-day meeting, a stimulating and diverse mixture of presentations were presented. This report attempts to highlight a selected number of presentations of this meeting.

Mucosal adjuvants

The vast majority of pathogens invade the body through or establish infections in the mucosal tissues. Development of vaccines to combat mucosal infections represents a top priority. Mucosal immunization has recently attracted much interest as a means of generating protective immunity against mucosal pathogens. Conversely, only very few mucosal vaccines are presently approved for human use. The development of a broad range of mucosal vaccines will necessitate the development of safe and effective mucosal adjuvants and delivery systems. Over the past decade, a number of immunomodulatory agents, including toxin based adjuvants, Toll like receptor (TLR) mimetics and non TLR-targeting immunostimulators as well as delivery systems have shown promise for mucosal administration in experimental animals. However, their possible use in humans remains to be established. This paper attempts to provide a brief overview of the mucosal immunization and adjuvants with an emphasis on mucosal adjuvants in or close to clinic.

Local cytokine and inflammatory responses to candidate vaginal adjuvants in mice

The current study was undertaken to explore the correlation of adjuvanticity and local inflammatory response elicited in the murine vagina and the draining lymph nodes following local administration of two candidate vaginal adjuvants, Toll like receptor (TLR) 9 agonist CpG ODN, and a non-TLR targeting molecule alpha-galactosylceramide (alpha-GalCer). Using real-time PCR array analysis, we could show that a group of 13 common cytokine genes are activated in the vagina within 24h after vaginal administration of these adjuvants, including Ccl2, Ccl7, Ccl12, Ccl19, Ccl20, Ccl22, Cxcl1, Cxcl5, Il10 and the Th1-inducing molecules Ifng, Cxcl9, Cxcl10 and Cxcl11. A high degree of inflammation in and damage to the epithelium was exclusively observed in the vagina of the CpG ODN treated mice, which was reversed within 48h. These results indicate that there is a group of common genes that correlate with the adjuvanticity of CpG ODN and alpha-GalCer in the vagina, and that alpha-GalCer induces less of local inflammatory reactions in the murine vagina compared to CpG ODN.

Induction of protective immunity by vaccination against Chlamydia trachomatis using the major outer membrane protein adjuvanted with CpG oligodeoxynucleotide coupled to the nontoxic B subunit of cholera toxin

The present study was undertaken to test the efficacy of immunization with the native major outer membrane protein (nMOMP) of Chlamydia trachomatis mouse pneumonitis (MoPn) serovar in combination with a novel immunostimulatory adjuvant consisting of CpG oligodeoxynucleotide (ODN) linked to the nontoxic B subunit of cholera toxin (CTB-CpG) to elicit a protective immune response to C. trachomatis. High levels of Chlamydia-specific IgG antibodies were detected in the sera from BALB/c mice immunized intramuscularly and subcutaneously (i.m.+s.c.) with the nMOMP/CTB-CpG vaccine or with nMOMP adjuvanted with a mixture of CT and CpG ODN (CT+CpG). Further, these immunization schemes gave rise to significant T-cell-mediated Chlamydia-specific immune responses. No Chlamydia-specific humoral or cell-mediated immune responses were detected in the control mice vaccinated with ovalbumin together with either CTB-CpG or CT+CpG. Following an intranasal challenge with C. trachomatis the groups of mice immunized with nMOMP plus CTB-CpG, CT+CpG or live C. trachomatis were found to be protected based on their change in body weight and lung weight as well as number of inclusion forming unit recovered from the lungs, as compared with control groups immunized with ovalbumin plus either adjuvants. Interestingly, IFN-gamma-producing CD4(+), but not CD8(+), T-cells showed a significant correlation with the outcomes of the challenge. In conclusion, nMOMP in combination with the novel adjuvant CTB-CpG elicited a significant antigen-specific antibody and cell-mediated immune responses as well as protection against a pulmonary challenge with C. trachomatis.

Vaccine adjuvants: scientific challenges and strategic initiatives

The majority of vaccine antigens currently under investigation represent recombinant molecules or subunits of pathogens with little or no inherent immunostimulatory property. The development of safe and potent immunologic adjuvants that can increase and direct vaccine-specific immunity is, therefore, required urgently. At the same time, the discovery of Toll-like receptors and other innate immune receptors with the ability to bridge innate immune responses and adaptive immunity is offering unprecedented opportunities for the development of novel adjuvants. However, research on vaccine adjuvants has so far received little attention as an independent scientific priority from most of the main research-funding agencies and policy makers. Further, adjuvant research and development is currently spread over a wide number of highly diverse organizations, including large commercial companies, small biotech enterprises as well as publicly funded research organizations and academia. More efforts are, therefore, needed to highlight the importance of vaccine adjuvants on the global research agenda and to encourage collaboration and flow of information between different stakeholders. This article attempts to underline scientific challenges and strategic priorities in the development of vaccine adjuvants for human use.

4th International Workshop in Vaccine Adjuvants and Parasitic Vaccines (adjuvant 2008)

The 4th International Workshop in Vaccine Adjuvants and Parasitic Vaccines (Adjuvant 2008), hosted by the Cuban Society for Immunology, attracted approximately 70 scientists from 22 countries. The meeting goal was mainly to share recent progress and discuss future challenges regarding vaccine adjuvants for the development of mucosal vaccines, as well as antiparasitic vaccines. Five keynote addresses, 21 oral presentations and 28 posters were presented, and the meeting was ended with a 'hot-topic' session discussing future challenges. This article highlights the most important issues discussed.

Suppression of HIV replication in vitro by CpG and CpG conjugated to the non toxic B subunit of cholera toxin

Administration of oligodeoxynucleotides (ODNs) containing CpG motifs generates a rapid and potent response of CC-chemokines, known as ligands of the HIV-1 co-receptor CCR5, in the murine female genital tract. The present study explored the potential HIV inhibitory activities of different human CpG prototypes either alone or conjugated to the non-toxic subunit of cholera toxin (CTB). Results showed that in vitro replication of both HIV-1 and HIV-2 can be suppressed by different human CpG prototypes. Importantly, the conjugation of CpG ODN to CTB (CTB-CpG) enhanced the antiviral activity of CpG against primary HIV-1 isolates of both R5 and X4 phenotypes in peripheral blood mononuclear cells (PBMC) as well as U87.CD4 co-receptor indicator cells. CTB-CpGs triggered higher amounts of MIP-1alpha, and MIP-1beta in PBMC than the corresponding CpG ODNs, which may explain the superior antiviral effect of CTB-CpG against R5 virus in PBMC. Incubation of PBMC with CpG ODN and CTB-CpG did not alter surface expression of HIV-1 receptors indicating that the observed anti-HIV-1 effect is not mediated through down regulation of HIV-1 receptors on target cells. Further, the enhanced antiviral effect of CTB-CpG was dependent on the presence of phosphorothioate backbone in the ODN, whereas the presence of CpG motif in ODNs was dispensable. These results have implications for the development of novel intervention strategies to prevent HIV infection.

Immunity against HIV/AIDS, malaria, and tuberculosis during co-infections with neglected infectious diseases: recommendations for the European Union research priorities

Infectious diseases remain a major health and socioeconomic problem in many low-income countries, particularly in sub-Saharan Africa. For many years, the three most devastating diseases, HIV/AIDS, malaria, and tuberculosis (TB) have received most of the world's attention. However, in rural and impoverished urban areas, a number of infectious diseases remain neglected and cause massive suffering. It has been calculated that a group of 13 neglected infectious diseases affects over one billion people, corresponding to a sixth of the world's population. These diseases include infections with different types of worms and parasites, cholera, and sleeping sickness, and can cause significant mortality and severe disabilities in low-income countries. For most of these diseases, vaccines are either not available, poorly effective, or too expensive. Moreover, these neglected diseases often occur in individuals who are also affected by HIV/AIDS, malaria, or TB, making the problem even more serious and indicating that co-infections are the rule rather than the exception in many geographical areas. To address the importance of combating co-infections, scientists from 14 different countries in Africa and Europe met in Addis Ababa, Ethiopia, on September 9–11, 2007. The message coming from these scientists is that the only possibility for winning the fight against infections in low-income countries is by studying, in the most global way possible, the complex interaction between different infections and conditions of malnourishment. The new scientific and technical tools of the post-genomic era can allow us to reach this goal. However, a concomitant effort in improving education and social conditions will be needed to make the scientific findings effective.

The adjuvant effect of CpG oligodeoxynucleotide linked to the non-toxic B subunit of cholera toxin for induction of immunity against H. pylori in mice

The present study was carried out to test the immunostimulatory and adjuvant effects of the non-toxic B subunit of cholera toxin (CTB), CpG oligodeoxynucleotide (ODN) and CpG ODN linked to CTB (CTB-CpG) for generation of immunity against H. pylori in mice. Herein, we showed that CTB-CpG induces more potent proinflammatory cytokine and chemokine responses in the cervical and the mesenteric lymph nodes (CLN and MLN, respectively) cells in vitro compared with those of CTB and CpG ODN. The adjuvant effects of these agents were examined following intranasal immunization of C57Bl/6 mice with H. pylori lysate in combination with CpG ODN, CTB or CTB-CpG. All three immunization regimes resulted in high H. pylori-specific IgG antibody responses; however, only the CTB-CpG and, to some extent, the CpG ODN immunized mice mounted a sustainable IgG2c antibody response. Importantly, mice immunized with H. pylori antigen and CTB-CpG or CpG ODN, but not CTB, developed strong H. pylori-specific proliferative and IFN-gamma responses in their MLN CD4+ T cells upon recall antigen stimulation in vitro. These mice also had significantly lower bacterial load compared with the control-infected mice. Furthermore, the CTB-CpG and the CpG ODN immunized mice developed increased specific IgA antibody responses in their gastrointestinal tracts following H. pylori challenge. These results imply that CTB-CpG and CpG ODN, but not CTB, could serve as nasal adjuvants for induction of a H. pylori-specific Th1 type immunity in MLN and also a specific mucosal IgA antibody response in the gastrointestinal tract upon H. pylori challenge.

Importance of myeloid differentiation factor 88 in innate and acquired immune protection against genital herpes infection in mice

Toll-like receptors (TLRs) play an important role as pattern-recognition receptors to sense and respond to pathogens. Our laboratory and others have shown recently that activation of TLR/MyD88 signaling through vaginal administration of CpG oligodeoxynucleotides, either singly or in combination with recombinant glycoprotein from herpes simplex virus type 2 (HSV-2), confers immunity against genital herpes infection. In this study, we have investigated the importance of the myeloid differentiation factor 88 (MyD88), a critical adaptor protein shared by all TLRs, in innate and acquired immunity against genital HSV-2 infection in mice. We demonstrate that MyD88 is essential for innate immune resistance against HSV-2. Thus, MyD88 deficient (MyD88(-/-)) mice show more vaginal HSV-2 titers, more rapid disease progression and earlier death compared to C57Bl/6 mice following a vaginal challenge with high (9 x 10(4) PFU) or low (9 x 10(3) PFU) virus dose. In contrast, use of MyD88 appears dispensable for induction of HSV-specific serum IgG antibody as well as local and systemic cell-mediated immune responses elicited by vaginal immunization with live attenuated thymidine kinase-deficient HSV-2 (HSV-2 TK(-)). Importantly, and similar to immunized C57Bl/6 mice, immunized MyD88(-/-) mice were completely protected against subsequent vaginal challenge with a lethal dose of virulent strain of HSV-2. These results provide evidence that the adaptor protein MyD88 is important for innate early control of genital HSV-2 infection, and that use of MyD88 is not required for induction of acquired immunity following vaginal immunization with HSV-2 TK(-).

Mucosal administration of CpG oligodeoxynucleotide elicits strong CC and CXC chemokine responses in the vagina and serves as a potent Th1-tilting adjuvant for recombinant gD2 protein vaccination against genital herpes

Although sexually transmitted pathogens are capable of inducing pathogen-specific immune responses, vaginal administration of nonreplicating antigens elicits only weak, nondisseminating immune responses. The present study was undertaken to examine the potential of CpG-containing oligodeoxynucleotide (CpG ODN) for induction of chemokine responses in the genital tract mucosa and also as a vaginal adjuvant in combination with glycoprotein D of herpes simplex virus type 2 (HSV-2) for induction of antigen-specific immune responses. We found that a single intravaginal administration of CpG ODN in mice stimulates a rapid and potent response of CC chemokines macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, and RANTES as well as of CXC chemokines MIP-2 and IP-10 in the vagina and/or the genital lymph nodes. Importantly, intravaginal vaccination with recombinant gD2 in combination with CpG ODN gave rise to a strong antigen-specific Th1-like immune response in the genital lymph nodes as well as the spleens of the vaccinated mice. Further, such an immunization scheme conferred both systemic and mucosal immunoglobulin G antibody responses as well as protection against an otherwise lethal vaginal challenge with HSV-2. These results illustrate the potential of CpG ODN for induction of potent chemokine responses in the genital tract and also as a vaginal adjuvant for generation of Th1-type mucosal and systemic immune responses towards a nonreplicating antigen derived from a sexually transmitted pathogen. These data have implications for the development of a mucosal vaccine against genital herpes and possibly other sexually transmitted diseases.

CpG oligodeoxynucleotides and mobilization of innate mucosal immunity: tasks and tactics

The recent discovery of pathogen-associated molecular patterns (PAMPs) as potential ligands for the evolutionary conserved innate immune receptors termed Toll-like receptors has enabled a modern era of immunotherapy using synthetic mimics of pathogen molecules. Among the PAMPs, bacterial DNA or synthetic oligodeoxynucleotides (ODNs) that contain unmethylated CpG motif shows promising effect on activation of systemic innate immune response. We could document that CpG ODN is capable of mobilizing a potent innate immunity in the mucosal tissues. Thus, intravaginal, intrarrectal, or intragastric delivery of mice with CpG ODN elicits potent innate chemokine responses in the respective mucosal tissues. Interestingly, we could show that the immunostimulatory effect of CpG DNA is much improved when chemically conjugated to the non-toxic B subunit of cholera toxin.