Whole recombinant Hansenula polymorpha expressing hepatitis B virus surface antigen (yeast-HBsAg) induces potent HBsAg-specific Th1 and Th2 immune responses

Recent studies have suggested that yeast cell wall components possess adjuvant activities. In the present study, heat-killed whole recombinant Hansenula polymorpha yeast expressing hepatitis B surface antigen (yeast-HBsAg) was generated, and the immune responses elicited by yeast-HBsAg were investigated in mice. The studies showed that yeast-HBsAg as well as yeast greatly promotes the accumulation of immune cells in mouse spleen and contributes to the maturation of dendritic cells (DCs). Yeast-HBsAg not only induces significantly higher antibody responses (including IgG, IgG1 and IgG2a), but also increases the IgG2a/IgG1 ratio, while alum combined with HBsAg (HBsAg + alum) only enhances antibody responses, but not the IgG2a/IgG1 ratio compared to HBsAg alone. Analysis of HBsAg-specific cytokines revealed that yeast-HBsAg is associated with production of both IFN-γ and IL-4, but neither IFN-γ nor IL-4 was detected in the HBsAg + alum-immunized group. Moreover, yeast-HBsAg induces potent HBsAg-specific lymphocyte proliferation and Cytotoxic T lymphocyte (CTL) responses. In conclusion, yeast-HBsAg enhances both HBsAg-specific Th1 and Th2 immune responses, while alum only enhances Th2 immune responses, suggesting that yeast-HBsAg may be an ideal candidate for an effective vaccine for the control of chronic hepatitis B virus (HBV) infection.     

Protective immunity induced by a DNA vaccine expressing eIF4A of Toxoplasma gondii against acute toxoplasmosis in mice

Toxoplasma gondii is an obligate intracellular protozoan parasite infecting humans, mammals and birds. Eukaryotic translation initiation factor (eIF4A) is a newly identified protein associated with tachyzoite virulence. To evaluate the protective efficacy of T. gondii eIF4A, a DNA vaccine (pVAX-eIF4A) encoding T. gondii eIF4A (Tg-eIF4A) gene was constructed. The expression ability of this recombinant DNA plasmid was examined in Marc145 cells by IFA. Then, Kunming mice were intramuscularly immunized with pVAX-eIF4A and followed by challenge infection with the highly virulent T. gondii RH strain. The results showed that vaccination with pVAX-eIF4A elicited specific humoral responses, with high IgG antibody titers and specific lymphocyte proliferative responses. The cellular immune response was associated with significant production of IFN-γ, IL-2 in Kunming mice, and a mixed IgG1/IgG2a response with predominance of IgG2a production, indicating that a Th1 type response was elicited after immunization with pVAX-eIF4A. In addition, the increase of the percentage of CD8+ T cells in lymphoid in mice suggested the activation of MHC class I restricted antigen presentation pathways. After lethal challenge, the mice vaccinated with the pVAX-eIF4A showed a significantly prolonged survival time (23.0 ± 5.5 days) compared with control mice which died within 7 days of challenge (P < 0.05). These results demonstrate that pVAX-eIF4A could elicit strong humoral, Th1-type cellular immune responses and increase survival time of immunized mice, suggesting that eIF4A is a promising vaccine candidate against acute T. gondii infection in mice.     

Immunization with inflammatory proteome of Brugia malayi adult worm induces a Th1/Th2-immune response and confers protection against the filarial infection

Mastomys coucha and jirds (Meriones unguiculatus) were immunized with four cytokine-stimulating SDS-PAGE resolved fractions F5 (68–84 kDa), F6 (54–68 kDa), F10 (38–42 kDa) and F14 (20–28 kDa) of Brugia malayi adult worm to determine which of these fractions has the potential to influence the establishment of subsequently introduced B. malayi infection in the animals. The proteins in the fractions were analyzed by 2DE and MALDI-TOF. Immunization with F6 suppressed the establishment of third stage larva (L₃) initiated infection in M. coucha (64%; P < 0.01) and jird (42%; P < 0.01). Survival of intraperitoneally implanted adult worms in M. coucha was lowered by F6 (72%; P < 0.01) and F14 (66%; P < 0.05) but not by F5 and F10. Immunization with F6 intensely upregulated both Th1 (IFN-γ, TNF-α, IL-1β, IL-2, IL-6, IgG1, IgG2a and lymphoproliferation) and Th2 (IgG2b and IL-10) responses and NO release. Immunostimulatory proteins HSP60, intermediate filament protein, and translation elongation factor EF-2 were identified in F6 fraction by 2DE and MALDI. The findings suggest that F6 protects the host from the parasite via Th1/Th2 type responses and thus holds promise for development as a vaccine.     

Induction of protective Th1 immune responses in mice by vaccination with recombinant Toxoplasma gondii nucleoside triphosphate hydrolase-II

The Toxoplasma gondii nucleoside triphosphate hydrolase (TgNTPase) has apyrase activity, degrading ATP to the di- and mono-phosphate forms and may be used by the parasite to salvage purines from the host cell for survival and replication. To study the immune-protective value of TgNTPase-II, BALB/c mice were immunized with a recombinant form of the antigen rTgNTPase-II combined with alum. All immunized mice produced specific anti-rTgNTPase-II immunoglobulins, with high IgG antibody titers and a mixed IgG1/IgG2a response, with predominance of IgG2a production. The cellular immune response was associated with the production of IFN-γ and IL-2 cytokines and the increase of the percentage of CD8+ T cells. Vaccinated mice displayed significant protection against acute infection with the virulent RH strain (P < 0.05 in survival rate) and also chronic infection with PRU cyst (62.9% and 57.6% reduction in brain parasite load for rTgNTPase-II + alum and rTgNTPase-II alone vaccinated groups) compared to the non-vaccinated control group. In conclusion, rTgNTPase-II elicits a strong specific Th1 immune response providing partial protection against both T. gondii acute and chronic infection.     

The virulence-related rhoptry protein 5 (ROP5) of Toxoplasma Gondii is a novel vaccine candidate against toxoplasmosis in mice

Infections with the intracellular protozoan parasite Toxoplasma gondii pose a serious public health problem and are of great economic importance worldwide. The parasite rhoptry protein 5 (ROP5) has been implicated as a major virulence factor that reduces the accumulation of immunity-related GTPases (IRG) in parasitophorous vacuole membrane (PVM), which maintains PVM integrity and evades IFNγ-mediated killing by intracellular parasites. To study the immunoprotective value of ROP5, BALB/c mice were immunized with a recombinant form of the protein administered alone or in combination with another promising vaccine antigen, rSAG1. All mice vaccinated with the recombinant antigens developed a high level of specific antibody responses against soluble tachyzoite antigens (STAg), a statistically significant increase of the splenocyte proliferation response, and significant levels of IFN-γ and IL-2 production. In contrast to rSAG1, which only stimulated the release of IFN-γ and IL-2, rROP5 induced the specific production of IL-10, the Th2-type cytokine, in addition to IFN-γ and IL-2. These results demonstrated that rROP5 could induce significant cellular and humoral (Th1/Th2) immune responses. Moreover, mice immunized with rROP5 displayed a prolonged survival time against a lethal challenge with the T. gondii RH strain. Additionally, vaccination with the mixture of rROP5 + rSAG1 resulted in higher levels of T. gondii-specific IgG antibodies and lymphocyte proliferative responses and conferred more efficient protection against T. gondii challenge compared to immunization with rROP5 or rSAG1 alone. Our studies show that recombinant ROP5 antigen may be a promising vaccine candidate against toxoplasmosis. To our knowledge, this is the first report to evaluate the immunoprotective value of ROP5.     

Protective effect against toxoplasmosis in mice induced by DNA immunization with gene encoding Toxoplasma gondii ROP18

Toxoplasma gondii is an obligate intracellular protozoan parasite infecting mammals and birds including humans. Rhoptry protein 18 has been implicated as an important virulence factor. In this study, we constructed a DNA vaccine expressing rhoptry protein 18 (ROP18) of T. gondii, and evaluated the immune response and protective immunity in Kunming mice. The gene sequence encoding ROP18 was inserted into the eukaryotic expression vector pVAX I. Intramuscular immunization of mice with pVAX-ROP18 elicited specific humoral responses and stimulated lymphoproliferation (P < 0.05). The cellular immune response was associated with the production of IFN-γ, indicating that a Th1 type response was elicited, which was confirmed by the production of large amounts of IgG2a (P < 0.05). By the expression of the CD69, an activation marker of CD4+ and CD8+ T cells, we found that pVAX-ROP18 enhanced the activation of CD4+ and CD8+ T cells in lymphoid in mice. After lethal challenge, the mice immunized with the pVAX-ROP18 showed a significantly increased survival time (27.9 ± 15.1 days) compared with control mice which died within 7 days of challenge (P < 0.05). Our results show for the first time, that a ROP18 vaccine construct can enhance the T. gondii-specific CTL. Th1 responses and increased survival suggested that ROP18 is a promising vaccine candidate against infection with T. gondii.     

Cationic lipid DC-Chol induces an improved and balanced immunity able to overcome the unresponsiveness to the hepatitis B vaccine.

Th1 and Th2 immune responses against antigens can be modulated by the use of adjuvants. Since antibody isotypes (IgG1 and IgG2a) and cytokines induced may reflect the Th differentiation taking place during the immune response, the humoral and cellular immune responses induced in mice against hepatitis B virus surface antigen (HBsAg) were examined when the antigen was either adsorbed to aluminum hydroxyde or administered with a new adjuvant the cationic lipid 3beta-[N-(N',N'-dimethylaminoethane)carbamoyl]cholesterol (DC-Chol). The use of DC-Chol increased antibody responses in responding BALB/c mice, induced more consistent IgG1 and IgG2a antibody responses in OF1 mice and overcame the nonresponse to HBsAg in B10.M mice. Furthermore, DC-Chol was able to induce cellular immune responses to HBsAg. The DC-Chol induced a balanced Th1/Th2 response, which enabled mice to overcome the inherited unresponsiveness to HBsAg encountered with aluminum-adjuvanted vaccine. Thus, the DC-Chol provides a signal to switch on both Th1 and Th2 responses, which may have important implications for vaccination against hepatitis B virus, as well as for enhancing weak immunogenicity of other recombinant purified antigens in a nonresponder population.     

The immune enhancement of a novel soy lecithin/β-glucans based adjuvant on native Neospora caninum tachyzoite extract vaccine in mice

Efficient, cost-effective and safe Th1-immunity-inducing vaccine formulations are paramount for achieving protection against Neospora caninum. In this study, a new adjuvant (Providean-AVEC^®) was used in the development of a N. caninum vaccine and evaluated in a mouse model. Soluble N. caninum tachyzoite native protein extract (sNcAg) was selected as vaccine antigen based on its capacity to activate production of pro-inflammatory cytokines on dendritic cells. Vaccines containing 4 and 0.4 μg of sNcAg, and Providean-AVEC^®, ISCOM-Matrix or aluminum hydroxide (Alum) were tested in BALB/c mice. While mice vaccinated with 4 μg of sNcAg + Providean-AVEC^® developed specific antibodies shortly after the first dose, the rest of the high antigen payload formulations only induced seroconversion after the booster. Mice immunized with the high payload ISCOM vaccine (4 μg sNcAg) or with either low or high payload Providean-AVEC^® formulations (0.4 μg and 4 μg sNcAg, respectively) elicited higher IgG2a than IgG1 serum levels, and IFN-γ anamnestic responses with a Th1-cytokine biased profile. These animals had no histological signs of cerebral lesions and parasite burden assessed by quantitative real-time PCR was not detected. Vaccine preparations including Providean-AVEC^® as adjuvant limited N. canimum multiplication even with only a tenth of antigen payload compared to vaccines containing other adjuvants. Using adjuvants to specifically activate dendritic cells, combined with a careful antigen selection can enhance cellular responses to inert N. caninum vaccines.     

Immunogenicity of highly conserved recombinant VacJ outer membrane lipoprotein of Pasteurella multocida

Bacterial lipoproteins are emerging targets for inducing protective immunity against many infectious diseases. VacJ is a highly conserved and widely distributed outer membrane lipoprotein of Pasteurella multocida strains, which are known to affect a wide range of domestic as well as wild animals and birds. In the present study, the gene encoding for mature VacJ outer membrane lipoprotein of P. multocida serogroup B:2 strain P52 was cloned and over-expressed in Escherichia coli as a fusion protein. The purified recombinant VacJ protein (∼44 kDa) was used for immunizing mice (6/group) along with adjuvants (FCA and alum) in two experiments. Immunization of mice with rVacJ (30 μg and 75 μg/mice) elicited humoral immune response with significant (P < 0.01) rise in antigen-specific titers of IgG and its subtypes (IgG1 and IgG2a). No protection was noticed in mice immunized with rVacJ (30 μg) along with FCA followed by challenge with 100 LD₅₀ of the homologous strain. On the contrary, higher rVacJ dose (75 μg) along with FCA and alum provided 66.7% and 50% protection respectively, at reduced challenge dose (8 LD₅₀). The study indicated that a lipidated recombinant VacJ lipoprotein with suitable adjuvants could potentially act as candidate antigen for vaccine development against pasteurellosis in livestock.     

RLJ-NE-299A: a new plant based vaccine adjuvant

Alum has been in use since long as an adjuvant for vaccines. However, its use as a vaccine adjuvant offers limitation in supporting cell mediated response. Therefore, a new plant based product RLJ-NE-299A from Picrorhiza kurroa reported for its immunostimulatory activity, has been explored for its potential as an alternative adjuvant. In order to compare the adjuvant activity with alum, antigen-specific immune responses were evaluated following immunization with a formulation containing hepatitis B surface antigen (HBsAg) adjuvanted with RLJ-NE-299A and alum in mice. The adjuvant RLJ-NE-299A up-regulated remarkably the expression of Th1 cytokines IL-2, IL-12, IFN-gamma, TNF alpha and Th2 cytokine IL-4 in lymph node cell cultures after 2 weeks of primary immunization with HBsAg. Further, the levels of both immunoglobulins IgG2a (Th1) and IgG1 (Th2) subtypes increased profoundly in blood sera of mice immunized with HBsAg/RLJ-NE-299A. The results indicated that RLJ-NE-299A has strong potential to increase both cell mediated and humoral immune responses and is capable of sustaining the total antigen-specific antibody response. Besides, the RLJ-NE-299A provides a signal to gear up both CD4 helper cells (Th1 and Th2) and CD8 cells populations, which may have important implications for vaccination against hepatitis B virus. Variable doses of RLJ-NE-299A (0.312-40 microg) containing vaccine antigen (HBsAg) were well tolerated with optimum T cell response at 2.5 microg/ml. Not only this, the adjuvant was also able to induce cellular immune responses to HBsAg as evidenced by Th1 and Th2 cytokines upregulation, which enabled mice to overcome the unresponsiveness to antigen HBsAg encountered with alum-adjuvanted vaccine in otherwise non-responding mice population. The study presents evidence that the HPLC standardized fraction RLJ-NE-299A, is an adjuvant of choice over alum in improving and maintaining the improved immune status against HBsAg, and may also prove useful adjuvant candidate with other vaccine antigens, too.     

An IL-15 adjuvant enhances the efficacy of a combined DNA vaccine against Brucella by increasing the CD8 cytotoxic T cell response

We investigated whether a combined DNA vaccine delivered together with the IL-15 gene (DNA-IL-15(+)) enhanced the immune response against Brucella abortus in mice. Mice vaccinated with DNA-IL-15(+) developed a robust humoral response; Brucella-specific antibodies exhibited a dominance of immunoglobulin G2a (IgG2a) over IgG1. Splenocytes from DNA-IL-15(+)-vaccinated mice induced significantly higher levels of IFN-γ (P < 0.01) and CD8⁺ T cell response (P < 0.01), suggesting induction of a T-helper-1-dominated immune response. In a specific cytotoxic-T-lymphocyte activity assay, DNA-IL-15(+) immunization elicited mainly CD8⁺ T cells, which mediate cytotoxicity, but also CD4⁺ T cells. In vivo depletion of T cell subsets showed that the DNA-IL-15(+)-induced protection against Brucella infection is mediated predominantly by CD8⁺ T cells, although CD4⁺ T cells also contribute. These data indicate that plasmid-delivered IL-15 increases the efficacy of the Brucella DNA vaccine.     

Immunogenicity and protective efficacy of ApxIA and ApxIIA DNA vaccine against Actinobacillus pleuropneumoniae lethal challenge in murine model

Actinobacillus pleuropneumoniae is the major etiological agent of swine pleuropneumonia that causes critical economic losses in swine industry. The use of DNA vaccines encoding Apx exotoxin structural proteins is a promising novel approach for immunization against A. pleuropneumoniae. The goal of this study was to design DNA vaccines which encode the gene of ApxIA or ApxIIA, and to evaluate the elicited immune responses and protective efficacy in mice. Significant humoral immune responses were induced by these DNA vaccines through intramuscular immunization. The IgG subclass (IgG1 and IgG2a) analysis indicates that divalent DNA vaccine induces both Th1 and Th2 immune responses. The protective efficacy was evaluated by the survival against lethal challenge with A. pleuropneumoniae serotype 1. The groups of vaccination with pcDNA-apxIA or divalent (pcDNA-apxIA and pcDNA-apxIIA) DNA vaccine provided protective efficacy significantly higher than that of the negative control groups (P < 0.05). However, pcDNA-apxIIA vaccine conferred protection was limited and not significant than that of the negative control groups (P > 0.05). These results show that the divalent DNA vaccine could confer the best protection. This finding indicates that DNA immunization should facilitate the development of a ‘third-generation’ of vaccines and provide a novel strategy against A. pleuropneumoniae infection.     

Enhancement of the immune responses to vaccination against foot-and-mouth disease in mice by oral administration of an extract made from Rhizoma Atractylodis Macrocephalae (RAM)

This study was designed to evaluate the effects of oral administration of a water extract made from the Rhizoma Atractylodis Macrocephalae (RAM) on the immune responses in mice immunized with FMDV type O vaccine. Thirty-five ICR mice were randomly divided into five groups with seven animals in each group, and orally administered daily for 4 days at a dose equivalent to 0, 0.0625, 0.125, 0.25 or 0.5 g of dried RAM, respectively. After that, the animals were subcutaneously immunized twice with FMDV vaccine at 2-week intervals. Blood samples were collected 3 weeks after boosting for measurement of FMDV-specific IgG titers and the IgG subclasses, lymphocyte proliferation as well as production IL-5 and IFN-γ. Results indicated that serum FMDV-specific IgG titers and the IgG subclass responses were significantly enhanced in mice orally administered RAM at the dose of 0.25 or 0.5 g when compared with the control group (P < 0.05). Splenocyte proliferation in response to Con A and LPS and production of IL-5 and IFN-γ by splenocytes were also significantly enhanced (P < 0.05). Considering the immunomodulatory effect and safety of RAM demonstrated in this study, this herb deserves further investigation to evaluate its potential improvement of FMD vaccination in other animals such as pigs, goats and cattle.     

Toll-like receptors and cytokines/cytokine receptors polymorphisms associate with non-response to hepatitis B vaccine

It is well documented that 5-10% hepatitis B adult vaccinees are non- and hypo-responders and probably are not adequately protected against hepatitis B virus (HBV) infection. The sequence variations of genes involved in processes such as pathogen recognition, antigen processing and presentation, and differentiation/maturation of lymphocytes may affect the duration and intensity of protective humoral immune response to the hepatitis B vaccine. In this study, frequencies of 53 known SNPs within 21 candidate genes were analyzed among 46 responders and 24 non-responders. Four SNPs (rs2243248, rs1805015, rs1295686 and rs3804100) in IL-4, IL-4RA, IL-13 and TLR2 genes were found significantly associated with the vaccinees’ status of serum anti-HBV response triggered by the vaccine (P < 0.05). Two SNPs (rs1295686 and rs1805015) also showed significant association with the vaccine-induced immune response when analyzed together with risk factors such as age and gender, by multivariable logistic regression analysis (P < 0.05). Further, haplotype analysis showed that the AG haplotype defined by SNPs rs1143633 (IL-1B; intron) and rs1143627 (IL-1B; intron) was present more frequently in non-responders than in responders (P = 0.035). Thus, specific SNPs in genes of cytokines/cytokine receptors and TLR2 were associated with status of the hepatitis B vaccine-induced protective humoral immune response.     

Amplified immune response by ginsenoside-based nanoparticles (ginsomes)

We describe here a novel adjuvant of ginsenoside-based nanoparticles (ginsomes) and its activity for up-regulation of immune response in mice. Ginsomes were assembled during removal of the detergent by dialysis in presence of ginseng saponins extracted from the root of Panax ginseng C.A. Meyer, cholesterol and phosphatidyl choline. The nanoparticles were spherical with diameters ranging from 70 to 107 nm, and contained ginsenosides Rb2, Rc, Rb1 and Rd. When co-administered with a model antigen ovalbumin (OVA) in ICR mice, ginsomes at a dose range from 10 to 250 μg promoted significantly higher IgG responses than OVA alone. Co-administration of ginsomes with OVA also significantly increased the levels of specific IgG1, IgG2a, IgG2b and IgG3, as well as T and B lymphocyte proliferation in response to Con A, LPS and OVA than when OVA was used alone. The enhanced IgG titer and subclass levels paralleled the increased production of IFN-γ (Th1 cytokine) and IL-5 (Th2 cytokine). Therefore, ginsomes as an adjuvant have up-regulated both Th1 and Th2 immune responses.     

OVA-bound nanoparticles induce OVA-specific IgG1, IgG2a,and IgG2b responses with low IgE synthesis

There is an urgent requirement for a novel vaccine that can stimulate immune responses without unwanted toxicity, including IgE elevation. We examined whether antigen ovalbumin (OVA) conjugated to the surface of nanoparticles (NPs) (OVA-NPs) with average diameter of 110 nm would serve as an immune adjuvant. When BALB/c mice were immunized with OVA-NPs, they developed sufficient levels of OVA-specific IgG1 antibody responses with low levels of IgE synthesis, representing helper T (Th)2-mediated humoral immunity. OVA-specific IgG2a and IgG2b responses (i.e., Th1-mediated immunity) were also induced by secondary immunization with OVA-NPs. As expected, immunization with OVA in alum (OVA-alum) stimulated humoral immune responses, including IgG1 and IgE antibodies, with only low levels of IgG2a/IgG2b antibodies. CD4-positive T cells from mice primed with OVA-NPs produced substantial levels of IL-21 and IL-4, comparable to those from OVA-alum group. The irradiated mice receiving OVA-NPs-primed B cells together with OVA-alum-primed T cells exhibited enhanced anti-OVA IgG2b responses relative to OVA-alum-primed B cells and T cells following stimulation with OVA-NPs. Moreover, when OVA-NPs-primed, but not OVA-alum-primed, B cells were cultured in the presence of anti-CD40 monoclonal antibody, IL-4, and IL-21, or LPS plus TGF-β in vitro, OVA-specific IgG1 or IgG2b antibody responses were elicited, suggesting that immunization with OVA-NPs modulates B cells to generate IgG1 and IgG2b responses. Thus, OVA-NPs might exert their adjuvant action on B cells, and they represent a promising potential vaccine for generating both IgG1 and IgG2a/IgG2b antibody responses with low IgE synthesis.     

Poly(lactide-co-glycolide) microspheres: A potent oral delivery system to elicit systemic immune response against inactivated rabies virus

Rabies is an endemic, fatal zoonotic disease in the developing countries. Oral vaccination strategies are suitable for rabies control in developing countries. Studies were performed to investigate the suitability of poly(lactide-co-glycolide) (PLG) microspheres as an oral delivery system for β-propiolactone inactivated concentrated rabies virus (CRV). Immune responses induced by encapsulated (PLG + CRV) and un-encapsulated inactivated rabies virus after oral and intraperitoneal route administrations were compared. The anti-rabies virus IgG antibody titer, virus neutralizing antibody (VNA) titers obtained by mouse neutralization test (MNT) and IgG2a and IgG1 titers of mice group immunized orally with PLG + CRV showed significantly (p < 0.001) higher response than the group immunized orally with un-encapsulated CRV. There was no significant difference (p > 0.05) between groups inoculated by intraperitoneal route. The stimulation index (SI) obtained by lymphoproliferation assay of PLG + CRV oral group also showed significantly (p < 0.001) higher response than the group immunized orally with un-encapsulated CRV, suggesting that oral immunization activates Th1-mediated cellular immunity. Immunized mice of all experimental groups were challenged intracerebrally with a lethal dose of virulent rabies virus Challenge Virus Standard (CVS). The survival rates of mice immunized orally with PLG + CRV and CRV alone were 75% and 50%, respectively, whereas intraperitoneally immunized groups showed 100% protection. The overall results of humoral, cellular immune response and survival rates of mice immunized orally with PLG + CRV were significantly (p < 0.001) higher than those of mice immunized orally with CRV alone. These data suggest that the PLG encapsulated inactivated rabies virus can be used for oral immunization against rabies.     

Prototype Alzheimer's disease epitope vaccine induced strong Th2-type anti-Abeta antibody response with Alum to Quil A adjuvant switch

Beta-amyloid (Abeta) peptide has been proposed to be a causal factor in Alzheimer's disease (AD). Currently being investigated, active and passive Abeta-immunotherapy significantly reduce Abeta plaque deposition, neuritic dystrophy, and astrogliosis in the brains of APP transgenic (APP/Tg) mice. Immunization with Abeta42 formulated in the Th1-type adjuvant QS21 was beneficial for AD patients with significant titers of anti-Abeta antibodies, however, 6% of participants developed meningoencephalitis, likely due to anti-Abeta-specific autoimmune Th1 cells. Thus, successful Abeta vaccination requires the development of strong antibody responses without Th1-type cellular immunity. In this study, we compared the induction of humoral immune responses with Th1-type (Quil A) and Th2-type (Alum) adjuvants singly and in combination, using our novel epitope vaccine composed of self B cell epitope Abeta(1-15) and foreign T cell epitope PADRE (PADRE-Abeta(1-15)-MAP). Formulated in Quil A, this vaccine resulted in significantly higher anti-Abeta antibody responses in both BALB/c (H-2d) and C57BL/6 (H-2b) mice, compared with Alum. Anti-Abeta antibodies induced by Alum were predominantly IgG1 type accompanied by lower levels of IgG2a and IgG2b. Quil A induced robust and almost equal titers of anti-Abeta antibodies of IgG1 and IgG2a isotypes and slightly lower levels of IgG2b. Switching adjuvants from Alum to Quil A induced higher concentrations of antibodies than injections with Alum only, however slightly lower than Quil A only. Switching both adjuvants did not change the profile of antibody responses generated by the initial adjuvant injected. These results suggest that switching from Alum to Quil A would be beneficial for AD patients because anti-Abeta antibody production was enhanced without changing the initially generated and likely beneficial Th2-type humoral response.