Suppression of endogenous IL-10 gene expression in dendritic cells enhances antigen presentation for specific Th1 induction: potential for cellular vaccine development

A new paradigm for designing vaccines against certain microbial pathogens, including Chlamydia trachomatis, is based on the induction of local mucosal Th1 response. IL-10 is an anti-inflammatory cytokine that exerts negative immunoregulatory influence on Th1 response. This study investigated whether biochemical modulation of endogenous IL-10 expression at the level of APCs is a practical strategy for enhancing the specific Th1 response against pathogens controlled by Th1 immunity. The results revealed that the high resistance of genetically engineered IL-10-/- (IL-10KO) mice to genital chlamydial infection is a function of the predilection of their APCs to rapidly and preferentially activate a high Th1 response. Thus, in microbiological analysis, IL-10KO mice suffered a shorter duration of infection, less microbial burden, and limited ascending infection than immunocompetent wild-type mice. Also, IL-10KO were resistant to reinfection after 8 wk of the primary infection. Cellular and molecular immunologic evaluation indicated that IL-10KO mice induced greater frequency of chlamydial-specific Th1 response following C. trachomatis infection. Moreover, IL-10KO APCs or antisense IL-10 oligonucleotide-treated wild-type APCs were potent activators of Th1 response from naive or immune T cells. Furthermore, both Ag-pulsed dendritic cells from IL-10KO mice and IL-10 antisense-treated dendritic cells from wild-type mice were efficient cellular vaccines in adoptive immunotherapeutic vaccination against genital chlamydial infection. These findings may furnish a novel immunotherapeutic strategy for boosting the Th1 response against T cell-controlled pathogens and tumors, using IL-10-deficient APCs as vaccine delivery agents.     

Codelivery of CCR7 ligands as molecular adjuvants enhances the protective immune response against herpes simplex virus type 1

Humoral and cellular immunity, associated with long-term protective immunological memory, defines the efficacy of a given vaccine formulation. However, few vaccines achieve this target without the aid of a suitable adjuvant. Molecular adjuvants in vaccination against infectious agents offer a noninvasive means of enhancing the immune response against target antigens. To examine the potency of two beta-chemokines as immunomodulators, plasmid DNA encoding beta-chemokines CCL19 and CCL21 (CCR7L) was codelivered intranasally with plasmid DNA or recombinant vaccinia virus encoding herpes simplex virus (HSV) gB (HSV-gB) in a prime-and-boost vaccination strategy. This vaccination regimen increased serum and vaginal immunoglobulin G (IgG) and IgA, respectively, as well as the numbers of HSV-gB(498-505) peptide-specific gamma interferon-producing CD8(+) T cells. Distinctively, a high number of cytotoxic T lymphocytes was achieved when pCCR7L was applied at both prime and boost as opposed to omission of pCCR7L. A rapid-recall response was induced in the genital tract upon challenge with the HSV McKrae strain, affording a high level of protection and survival of vaccinated mice. Our results demonstrate that high innate immune kinetics and distribution of adaptive response induced in the nasal mucosa appears to be key factors in generating protective memory responses against HSV. Thus CCR7L expressed ectopically may serve as a molecular adjuvant to boost the immune response to a codelivered antigen in mucosal surfaces.     

Baseline levels of influenza-specific CD4 memory T-cells affect T-cell responses to influenza vaccines

Background

Factors affecting immune responses to influenza vaccines have not been studied systematically. We hypothesized that T-cell and antibody responses to the vaccines are functions of pre-existing host immunity against influenza antigens.

Methodology/Principal Findings

During the 2004 and 2005 influenza seasons, we have collected data on cellular and humoral immune reactivity to influenza virus in blood samples collected before and after immunization with inactivated or live attenuated influenza vaccines in healthy children and adults. We first used cross-validated lasso regression on the 2004 dataset to identify a group of candidate baseline correlates with T-cell and antibody responses to vaccines, defined as fold-increase in influenza-specific T-cells and serum HAI titer after vaccination. The following baseline parameters were examined: percentages of influenza-reactive IFN-γ⁺ cells in T and NK cell subsets, percentages of influenza-specific memory B-cells, HAI titer, age, and type of vaccine. The candidate baseline correlates were then tested with the independent 2005 dataset. Baseline percentage of influenza-specific IFN-γ⁺ CD4 T-cells was identified as a significant correlate of CD4 and CD8 T-cell responses, with lower baseline levels associated with larger T-cell responses. Baseline HAI titer and vaccine type were identified as significant correlates for HAI response, with lower baseline levels and the inactivated vaccine associated with larger HAI responses. Previously we reported that baseline levels of CD56^dim NK reactivity against influenza virus inversely correlated with the immediate T-cell response to vaccination, and that NK reactivity induced by influenza virus depended on IL-2 produced by influenza-specific memory T-cells. Taken together these results suggest a novel mechanism for the homeostasis of virus-specific T-cells, which involves interaction between memory helper T-cells, CD56^dim NK and DC.

Significance

These results demonstrate that assessment of baseline biomarkers may predict immunologic outcome of influenza vaccination and may reveal some of the mechanisms responsible for variable immune responses following vaccination and natural infection.     

Live attenuated herpes simplex virus 2 glycoprotein E deletion mutant as a vaccine candidate defective in neuronal spread

A herpes simplex virus 2 (HSV-2) glycoprotein E deletion mutant (gE2-del virus) was evaluated as a replication-competent, attenuated live virus vaccine candidate. The gE2-del virus is defective in epithelial cell-to-axon spread and in anterograde transport from the neuron cell body to the axon terminus. In BALB/c and SCID mice, the gE2-del virus caused no death or disease after vaginal, intravascular, or intramuscular inoculation and was 5 orders of magnitude less virulent than wild-type virus when inoculated directly into the brain. No infectious gE2-del virus was recovered from dorsal root ganglia (DRG) after multiple routes of inoculation; however, gE2-del DNA was detected by PCR in lumbosacral DRG at a low copy number in some mice. Importantly, no recurrent vaginal shedding of gE2-del DNA was detected in immunized guinea pigs. Intramuscular immunization outperformed subcutaneous immunization in all parameters evaluated, although individual differences were not significant, and two intramuscular immunizations were more protective than one. Immunized animals had reduced vaginal disease, vaginal titers, DRG infection, recurrent genital lesions, and recurrent vaginal shedding of HSV-2 DNA; however, protection was incomplete. A combined modality immunization using live virus and HSV-2 glycoprotein C and D subunit antigens in guinea pigs did not totally eliminate recurrent lesions or recurrent vaginal shedding of HSV-2 DNA. The gE2-del virus used as an immunotherapeutic vaccine in previously HSV-2-infected guinea pigs greatly reduced the frequency of recurrent genital lesions. Therefore, the gE2-del virus is safe, other than when injected at high titer into the brain, and is efficacious as a prophylactic and immunotherapeutic vaccine.     

Genital herpes simplex.

Genital herpes is a sexually transmitted disease caused by the herpes simplex virus. Following the initial infection the virus becomes latent in the sacral ganglia. Approximately 80% of patients are then subject to milder but unpredictable recurrences and may shed the virus even when they are asymptomatic. The disorder causes concern because genital herpes in the mother can result in rare but catastrophic neonatal infection and because of a possible association between genital herpes and cancer of the cervix. No effective treatment is as yet available. Weekly monitoring for virus by cervical culture from 32 weeks'' gestation is recommended for women with a history of genital herpes and for those whose sexual partner has such a history.     

Temporal and anatomic relationship between virus replication and cytokine gene expression after vaginal simian immunodeficiency virus infection

The current knowledge about early innate immune responses at mucosal sites of human immunodeficiency virus (HIV) entry is limited but likely to be important in the design of effective HIV vaccines against heterosexual transmission. This study examined the temporal and anatomic relationship between virus replication, lymphocyte depletion, and cytokine gene expression levels in mucosal and lymphoid tissues in a vaginal-transmission model of HIV in rhesus macaques. The results of the study show that the kinetics of cytokine gene expression levels in the acute phase of infection are positively correlated with virus replication in a tissue. Thus, cytokine responses after vaginal simian immunodeficiency virus (SIV) inoculation are earliest and strongest in mucosal tissues of the genital tract and lowest in systemic lymphoid tissues. Importantly, the early cytokine response was dominated by the induction of proinflammatory cytokines, while the induction of cytokines with antiviral activity, alpha/beta interferon, occurred too late to prevent virus replication and dissemination. Thus, the early cytokine response favors immune activation, resulting in the recruitment of potential target cells for SIV. Further, unique cytokine gene expression patterns were observed in distinct anatomic locations with a rapid and persistent inflammatory response in the gut that is consistent with the gut being the major site of early CD4 T-cell depletion in SIV infection.     

Therapeutic immunization with a virion host shutoff-defective, replication-incompetent herpes simplex virus type 1 strain limits recurrent herpetic ocular infection

Immunization of mice with herpes simplex virus type 1 (HSV-1) mutant viruses containing deletions in the gene for virion host shutoff (vhs) protein diminishes primary and recurrent corneal infection with wild-type HSV-1. vhs mutant viruses are severely attenuated in vivo but establish latent infections in sensory neurons. A safer HSV-1 mutant vaccine strain, Delta41Delta29, has combined vhs and replication (ICP8-) deficits and protects BALB/c mice against primary corneal infection equivalent to a vhs- strain (BGS41). Here, we tested the hypothesis that Delta41Delta29 can protect as well as BGS41 in a therapeutic setting. Because immune response induction varies with the mouse and virus strains studied, we first determined the effect of prophylactic Delta41Delta29 vaccination on primary ocular infection of NIH inbred mice with HSV-1 McKrae, a model system used to evaluate therapeutic vaccines. In a dose-dependent fashion, prophylactic Delta41Delta29 vaccination decreased postchallenge tear film virus titers and ocular disease incidence and severity while eliciting high levels of HSV-specific antibodies. Adoptive transfer studies demonstrated a dominant role for immune serum and a lesser role for immune cells in mediating prophylactic protection. Therapeutically, vaccination with Delta41Delta29 effectively reduced the incidence of UV-B-induced recurrent virus shedding in latently infected mice. Therapeutic Delta41Delta29 and BGS41 vaccination decreased corneal opacity and delayed-type hypersensitivity responses while elevating antibody titers, compared to controls. These data indicate that replication is not a prerequisite for generation of therapeutic immunity by live HSV mutant virus vaccines and raise the possibility that genetically tailored replication-defective viruses may make effective and safe therapeutic vaccines.     

Efficacy of DNA and fowlpox virus priming/boosting vaccines for simian/human immunodeficiency virus

Further advances are required in understanding protection from AIDS by T-cell immunity. We analyzed a set of multigenic simian/human immunodeficiency virus (SHIV) DNA and fowlpox virus priming and boosting vaccines for immunogenicity and protective efficacy in outbred pigtail macaques. The number of vaccinations required, the effect of DNA vaccination alone, and the effect of cytokine (gamma interferon) coexpression by the fowlpox virus boost was also studied. A coordinated induction of high levels of broadly reactive CD4 and CD8 T-cell immune responses was induced by sequential DNA and fowlpox virus vaccination. The immunogenicity of regimens utilizing fowlpox virus coexpressing gamma interferon, a single DNA priming vaccination, or DNA vaccines alone was inferior. Significant control of a virulent SHIV challenge was observed despite a loss of SHIV-specific proliferating T cells. The outcome of challenge with virulent SHIV(mn229) correlated with vaccine immunogenicity except that DNA vaccination alone primed for protection almost as effectively as the DNA/fowlpox virus regimen despite negligible immunogenicity by standard assays. These studies suggest that priming of immunity with DNA and fowlpox virus vaccines could delay AIDS in humans.     

A live-attenuated HSV-2 ICP0 virus elicits 10 to 100 times greater protection against genital herpes than a glycoprotein D subunit vaccine

Glycoprotein D (gD-2) is the entry receptor of herpes simplex virus 2 (HSV-2), and is the immunogen in the pharmaceutical industry''s lead HSV-2 vaccine candidate. Efforts to prevent genital herpes using gD-2 subunit vaccines have been ongoing for 20 years at a cost in excess of $100 million. To date, gD-2 vaccines have yielded equivocal protection in clinical trials. Therefore, using a small animal model, we sought to determine if a live-attenuated HSV-2 ICP0 ⁻ virus would elicit better protection against genital herpes than a gD-2 subunit vaccine. Mice immunized with gD-2 and a potent adjuvant (alum+monophosphoryl lipid A) produced high titers of gD-2 antibody. While gD-2-immunized mice possessed significant resistance to HSV-2, only 3 of 45 gD-2-immunized mice survived an overwhelming challenge of the vagina or eyes with wild-type HSV-2 (MS strain). In contrast, 114 of 115 mice immunized with a live HSV-2 ICP0 ⁻ virus, 0ΔNLS, survived the same HSV-2 MS challenges. Likewise, 0ΔNLS-immunized mice shed an average 125-fold less HSV-2 MS challenge virus per vagina relative to gD-2-immunized mice. In vivo imaging demonstrated that a luciferase-expressing HSV-2 challenge virus failed to establish a detectable infection in 0ΔNLS-immunized mice, whereas the same virus readily infected naïve and gD-2-immunized mice. Collectively, these results suggest that a HSV-2 vaccine might be more likely to prevent genital herpes if it contained a live-attenuated HSV-2 virus rather than a single HSV-2 protein.     

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.     

The influence of homologous vs. heterologous challenge virus strains on the serological test results of rabies virus neutralizing assays

The effect that the relatedness of the viral seed strain used to produce rabies vaccines has to the strain of challenge virus used to measure rabies virus neutralizing antibodies after vaccination was evaluated. Serum samples from 173 subjects vaccinated with either purified Vero cell rabies vaccine (PVRV), produced from the Pittman Moore (PM) seed strain of rabies virus, or purified chick embryo cell rabies vaccine (PCECV), produced from the Flury low egg passage (Flury-LEP) seed strain of rabies virus, were tested in parallel assays by RFFIT using a homologous and a heterologous testing system. In the homologous system, CVS-11 was used as the challenge virus in the assay to evaluate the humoral immune response in subjects vaccinated with PVRV and Flury-LEP was used for subjects vaccinated with PCECV. In the heterologous system, CVS-11 was used as the challenge virus in the assay to evaluate subjects vaccinated with PCECV and Flury-LEP was used for subjects vaccinated with PVRV. Although the difference in G protein homology between the CVS-11 and Flury-LEP rabies virus strains has been reported to be only 5.8%, the use of a homologous testing system resulted in approximately 30% higher titers for nearly two-thirds of the samples from both vaccine groups compared to a heterologous testing system. The evaluation of equivalence of the immune response after vaccination with the two different vaccines was dependent upon the type of testing system, homologous or heterologous, used to evaluate the level of rabies virus neutralizing antibodies. Equivalence between the vaccines was achieved when a homologous testing system was used but not when a heterologous testing system was used. The results of this study indicate that the strain of virus used in the biological assays to measure the level of rabies virus neutralizing antibodies after vaccination could profoundly influence the evaluation of rabies vaccines.     

Vaccination alters the balance between protective immunity, exhaustion, escape, and death in chronic infections

While T cell-based vaccines have the potential to provide protection against chronic virus infections, they also have the potential to generate immunopathology following subsequent virus infection. We develop a mathematical model to investigate the conditions under which T cells lead to protection versus adverse pathology. The model illustrates how the balance between virus clearance and immune exhaustion may be disrupted when vaccination generates intermediate numbers of specific CD8 T cells. Surprisingly, our model suggests that this adverse effect of vaccination is largely unaffected by the generation of mutant viruses that evade T cell recognition and cannot be avoided by simply increasing the quality (affinity) or diversity of the T cell response. These findings should be taken into account when developing vaccines against persistent infections.     

Intranasal Vaccination Promotes Detrimental Th17-Mediated Immunity against Influenza Infection

Influenza disease is a global health issue that causes significant morbidity and mortality through seasonal epidemics. Currently, inactivated influenza virus vaccines given intramuscularly or live attenuated influenza virus vaccines administered intranasally are the only approved options for vaccination against influenza virus in humans. We evaluated the efficacy of a synthetic toll-like receptor 4 agonist CRX-601 as an adjuvant for enhancing vaccine-induced protection against influenza infection. Intranasal administration of CRX-601 adjuvant combined with detergent split-influenza antigen (A/Uruguay/716/2007 (H3N2)) generated strong local and systemic immunity against co-administered influenza antigens while exhibiting high efficacy against two heterotypic influenza challenges. Intranasal vaccination with CRX-601 adjuvanted vaccines promoted antigen-specific IgG and IgA antibody responses and the generation of polyfunctional antigen-specific Th17 cells (CD4⁺IL-17A⁺TNFα⁺). Following challenge with influenza virus, vaccinated mice transiently exhibited increased weight loss and morbidity during early stages of disease but eventually controlled infection. This disease exacerbation following influenza infection in vaccinated mice was dependent on both the route of vaccination and the addition of the adjuvant. Neutralization of IL-17A confirmed a detrimental role for this cytokine during influenza infection. The expansion of vaccine-primed Th17 cells during influenza infection was also accompanied by an augmented lung neutrophilic response, which was partially responsible for mediating the increased morbidity. This discovery is of significance in the field of vaccinology, as it highlights the importance of both route of vaccination and adjuvant selection in vaccine development     

Enhancement of protective humoral immune responses against Herpes simplex virus-2 in DNA-immunized guinea-pigs using protein boosting

Genital Herpes is a common sexually transmitted disease that is caused mostly by Herpes simplex virus type 2 (HSV-2). Its prevalence has increased in developing countries in spite of the availability of valuable antiviral drug therapy. Considering the importance of HSV-2 infections, effective vaccines remain the most likely hope for controlling the spread of HSV diseases. In the present study, the complete HSV-2 glycoprotein D gene was isolated and cloned into different plasmid vectors to construct a DNA vaccine and prepare recombinant subunit vaccines using a baculovirus expression system. The vaccines were tested alone or in combination to evaluate their ability to induce protective immunity in guinea-pigs against genital HSV infections. Immunization elicited humoral responses as measured by neutralization tests and enzyme-linked immunosorbent assay, and immunized animals had less severe genital skin disease as well as reduced replication of the challenging virus in the genital tract during experimental infection. Our results further demonstrate that DNA priming-protein boosting induced a neutralizing antibody titer higher than that obtained with DNA-DNA vaccination. The massive increase of antibody titer following DNA priming-protein boosting might be attributed to a recall of B cell memory.     

Role of immunostimulatory molecules in poultry vaccines

Immunization by vaccination is the most suitable and safest method for preventing infectious diseases in the poultry worldwide. Vaccines alone cannot effectively protect birds from variety of pathogens under field conditions. The combined use of potent immunostimulants in vaccines is an alternative to increase the efficacy of vaccines that can be achieved by the development of better adjuvant. One such adjuvant is cytokine; cytokines have been used extensively as adjuvant in vaccines and are responsible for the type and extent of an immune response following vaccination. Although the innate immune system in birds is not fully characterized but their immune system is very much similar to that of mammals, and moreover with the recent discovery of a number of avian cytokine genes it is now possible to study their effectiveness in enhancing the immune response during vaccination. This review focuses on the recent studies and developments involving the role of immunomodulating agents especially cytokines of avian origin in poultry vaccines.     

Towards a new generation of vaccines: the cytokine IL-12 as an adjuvant to enhance cellular immune responses to pathogens during prime-booster vaccination regimens

A main goal of the industrialized world is the development of effective vaccines to control infectious diseases with major health and socio-economic impact. Current understanding of the immune response triggered during infection with pathogens causing malaria, hepatitis C and AIDS emphasizes the importance of cytotoxic T lymphocytes (CTLs) in combating these infections. This has led to the development of new vaccination strategies, some of which are in phase I/II clinical trials. Promising strategies of vaccination are based on highly attenuated viral vectors, such as Vaccinia virus (VV) in combination with heterologous like vectors naked DNA, referred to as priming/booster vaccination. While these immunization schedules increased the production of specific CTLs, there is a need to further expand the CD8+T cell population to control an infection. Among molecules that play a significant role in the modulation of the CTL response is the cytokine IL-12. Immunoregulation by IL-12 is of central importance in cell-mediated immunity (CMI) against those pathogens and tumors that are controlled by cell-mediated mechanisms, supported by Thl cells. The use of this cytokine in combination with highly immunogenic VV-derived vectors is a promising system for development of future vaccination schedules. In this review, we summarize recent data on the use of IL-12 in vaccination procedures, as well as undesired side-effects of the cytokine that can be overcome by accurate use of dose, route and time-window administration of IL-12 encoding vectors. Results described here indicate that VV IL-12-mediated enhancement of the specific CMI response against a model antigen HIV-1 env was time- and dose-dependent and that the antigen and the cytokine could be expresed from two different rVVs modulating the doses of the vectors and allowing for enhancement of a specific CMI response. Moreover, the use of IL-12 during DNA prime/VV boost regimens enhanced the specific anti-HIV-1 env cellular response 20 times compared to that generated after a single rVVenv inoculation. Variables such as: a) dose of the cytokine applied, b) time of its administration and c) routes of inoculation play a critical role in the final outcome of the response. The findings presented here can be extended to other antigens, suggesting that immunomodulatory cytokines can be useful in the development of the future vaccines against numerous infectious diseases and tumors.     

Adjuvant activity of type I interferons

Type I interferons (IFNs) produced primarily by plasmacytoid dendritic cells (pDCs) as part of the innate immune response to infectious agents induce the maturation of myeloid DCs and enhance antigen presentation. Type I IFNs also enhance apoptosis of virus-infected cells, stimulate cross priming and enhanced presentation of viral peptides. Type I IFNs are powerful polyclonal B-cell activators that induce a strong primary humoral immune response characterized by isotype switching and protection against virus challenge. Type I IFNs stimulate an IgG2a antibody response characteristic of Th1 immunity when ad-mixed with influenza virus vaccine and injected intramuscurarly (i.m.) or administered intranasally. The adjuvant activity of type I IFNs has been shown to involve direct effects of IFN on B-cells, effects on T-cells, as well as effects on antigen presentation. Oromucosal administration of type I IFNs concomitantly with i.m. injection of vaccine alone can also enhance the antibody response to influenza vaccination by enhancing trafficking of antigen-presenting cells towards the site of vaccination. Recombinant IFNs are potent adjuvants that may find application in both parenterally and mucosally administered vaccines.     

Cytokines as potential vaccine adjuvants

There is a compelling clinical need for adjuvants suitable for human use to enhance the efficacy of vaccines in the prevention of life-threatening infection. Candidate populations for such vaccine-adjuvant strategies include normal individuals at the two extremes of life, as well as the ever increasing population of immunocompromised individuals. In addition, adjuvants that would increase the efficiency of vaccination with such vaccines as those directed against hepatitis B andStreptococcus pneumoniae would have an even greater general use. Cytokines, as natural peptides intimately involved in the normal immune response, have great appeal as potential adjuvants. An increasing body of work utilizing recombinant versions of interleukin-1, -2, -3, -6, -12, gamma-interferon, tumor necrosis factor, and granulocyte-monocyte-colony stimulating factor has shown that cytokines do have vaccine adjuvant activity. However, in order to optimize adjuvant effect and minimize systemic toxicity, strategies in which the cytokine is fused to the antigen, or the cytokine is presented within liposomes or microspheres appear to be necessary to make this a practical approach suitable for human use. There is much promise in this approach, but there is much work to be accomplished in order to optimize the pharmacokinetics of cytokine administration as well as its side effect profile.Abbreviations IL interleukin - TNF tumor necrosis factor - NK natural killer - pIL-1 interleukin-1 peptide - LPS lipopolysaccharide - r recombinant - HSV-2 herpes simplex virus 2 - gamma     

Systemic and mucosal immunity induced by oral somatic transgene vaccination against glycoprotein B of pseudorabies virus using live attenuated Salmonella typhimurium

Glycoprotein B mediates the absorption and penetration of the pseudorabies virus in the form of an immunodominant Ag, and represents a major target for the development of new vaccines. This study evaluated the efficiency of live attenuated Salmonella typhimurium SL7207 for the oral delivery of DNA vaccine encoding the pseudorabies virus glycoprotein B (pCI-PrVgB) in vivo, leading to the generation of both systemic and mucosal immunity against the pseudorabies virus Ag. An oral transgene vaccination of pCI-PrVgB using a Salmonella carrier produced a broad spectrum of immunity at both the systemic and mucosal sites, whereas the intramuscular administration of a naked DNA vaccine elicited no mucosal immunoglobulin (Ig)A response. Interestingly, the Salmonella-mediated oral transgene vaccination of the pseudorabies virus glycoprotein B biased the immune responses to the Th2-type, as determined by the IgG2a/IgG1 ratio and the cytokine production profile. However, oral vaccination mediated by Salmonella harbouring pCI-PrVgB showed inferior protection to systemic immunization against virulent pseudorabies virus infection. The expression of transgene delivered by Salmonella bacteria in antigen-presenting cells of both the systemic and mucosal-associated lymphoid tissues was further demonstrated. These results highlight the potential use of live attenuated S. typhimurium for an oral transgene pseudorabies virus glycoprotein B vaccination to induce broad immune responses.