Parenteral and mucosal prime-boost immunization strategies in mice with hepatitis B surface antigen and CpG DNA

Synthetic oligodeoxynucleotides (ODN) containing immunostimulatory CpG motifs (CpG ODN) are potent adjuvants to protein antigens administered by parenteral or mucosal routes to BALB/c mice. To date, there have been no studies using combined parenteral/mucosal approaches with CpG DNA as adjuvant. In this study we evaluated different parenteral prime-mucosal boost and mucosal prime-parenteral boost strategies using hepatitis B surface antigen (HBsAg) alone or with different adjuvants: aluminum hydroxide (alum), cholera toxin (CT), CpG ODN. In addition, since CpG ODN has previously been shown to act synergistically with other adjuvants after parenteral or mucosal delivery, we also evaluated adjuvant combinations: alum+CpG ODN and CT+CpG ODN. The effects of adjuvant and administration strategy on systemic and mucosal humoral responses were measured, as well as cell-mediated immune responses (cytotoxic T lymphocyte activity). These results were compared to parenteral only or mucosal only strategies. Our findings demonstrate that parenteral immunization can prime for mucosal responses even when different lymph nodes were being targeted. HBsAg-specific immune responses (IgG in plasma, cytotoxic T lymphocytes) induced by parenteral prime could all be significantly enhanced by mucosal boosting and despite the fact that intramuscular immunization alone could not induce mucosal IgA, it could prime for a subsequent mucosal boost. In addition, the presence of adjuvant at time of boosting could influence the nature of subsequent immune responses (Th1 vs. Th2). Mice primed intranasally could have their systemic immune responses boosted with a parenteral administration and it was also possible to enhance mucosal responses induced by intranasal prime with an intramuscular boost.     

Adjuvant effect of CIA07, a combination of Escherichia coli DNA fragments and modified lipopolysaccharides, on the immune response to hepatitis B virus surface antigen

CIA07 is an immunostimulatory agent composed of bacterial DNA fragments and modified lipopolysaccharide, which has antitumor activity against bladder cancer in mice. In this study, the adjuvant activity of CIA07 was evaluated using hepatitis B virus surface antigen (HBsAg) as the immunogen. Mice were immunized intramuscularly three times at 1-week intervals with HBsAg alone or in combination with alum, bacterial DNA fragments, modified lipopolysaccharide, CIA07 or CpG1826, and immune responses were assessed. At 1 week after the final injection, the HBsAg-specific total serum IgG antibody titer in CIA07-treated mice was 14 times higher than that in animals administered antigen alone, six times higher than in mice given alum or bacterial DNA fragments and twice as high as those treated with modified lipopolysaccharide or CpG1826, and remained maximal until 8 weeks postimmunization. Animals receiving antigen alone or plus alum displayed barely detectable HBsAg-specific serum IgG2a antibody responses. However, coadministration of CIA07 with antigen led to markedly enhanced serum IgG2a antibody titer and IFN-gamma(+) production in splenocytes, indicating that CIA07 effectively induces Th1-type immune responses. In addition, the number of HBsAg-specific CD8(+) T cells in peripheral blood mononuclear cells was elevated in CIA07-treated mice. These data clearly demonstrate that CIA07 is able to induce both cellular and humoral immune responses to HBsAg, and confirm its potential as an adjuvant in therapeutic vaccines for hepatitis B virus infections.     

CpG Oligodeoxynucleotides with Hepatitis B Surface Antigen (HBsAg) for Vaccination in HBsAg-Transgenic Mice

DNA motifs containing unmethylated CpG dinucleotides within the context of certain flanking sequences enhance both innate and antigen-specific immune responses, due in part to the enhanced production of Th1-type cytokines. Here we explored the ability of CpG-containing oligodeoxynucleotides combined with recombinant hepatitis B surface antigen (HBsAg) to induce Th1 responses in mice that are transgenic for this antigen and that represent a model for asymptomatic hepatitis B virus chronic carriers. This was compared to hepatitis B virus-specific DNA-mediated immunization, which we have previously shown to induce the clearance of the transgene expression product and the down-regulation of hepatitis B virus mRNA in this transgenic mouse lineage. In control nontransgenic C57BL/6 mice, three immunizations with HBsAg and CpG triggered the production of anti-HBs antibodies and of HBs-specific T cells that secrete gamma interferon but do not display any HBsAg-specific cytotoxic activity. In the HBsAg-transgenic mice, immunization with HBsAg and CpG oligodeoxynucleotides, but not with CpG alone, induced the clearance of HBsAg circulating in the sera, with a concomitant appearance of specific antibodies, and was able to regulate the hepatitis B virus mRNA constitutively expressed in the liver. Finally, adoptive transfer experiments with CD8(+) T cells primed in C57BL/6 mice with HBsAg and CpG oligodeoxynucleotide-based immunization show that these cells were able to partially control transgene expression in the liver and to clear the HBsAg from the sera of recipient transgenic mice without an antibody requirement. CpG oligodeoxynucleotides motifs combined with HBsAg could therefore represent a potential therapeutic approach with which to treat chronically infected patients.     

Intranasal immunization of mice with CpG DNA induces strong systemic and mucosal responses that are influenced by other mucosal adjuvants and antigen distribution

BACKGROUND: Synthetic oligodeoxynucleotides (ODN) containing immunostimulatory cytosine-guanine phosphate-linked dinucleotide (CpG) motifs are potent systemic and mucosal adjuvants in mice that have synergistic action with numerous other adjuvants, including alum and cholera toxin (CT). Herein, we evaluate CpG ODN with intranasal (IN) delivery of purified hepatitis B surface antigen (HBsAg), relative to and in combination with CT, Escherichia coli heat labile enterotoxin (LT), the B subunit of CT (CTB), and a nontoxic derivative of LT (LTK63). MATERIALS AND METHODS: BALB/c mice were immunized by IN administration of HBsAg, alone or combined with CT, LT, CTB, or LTK63, and/or CpG ODN, or non-CpG control ODN. In addition, the effect of low-or high-volume administration was assessed, in order to target upper respiratory or entire respiratory tract, respectively. HBsAg-specific systemic (immunoglobulins: IgG, IgG1, IgG2a in plasma) and mucosal (IgA in fecal, lung, vaginal, saliva, and gut samples) humoral responses, as well as cell-mediated immune responses including T-cell proliferation and cytokines (interleukins: IL-4, IL-5; interferon: IFN-gamma) were evaluated. RESULTS: CpG ODN, CT, and LT augmented anti-HBs titers equally, and more so than did CTB or LTK63. CpG ODN acted synergistically with CT and LT, but not CTB or LTK63 to enhance anti-HBs titers. Nevertheless, CpG ODN induced a more Th1-like response for all combinations, compared with the same formulation without CpG. Strength of induced systemic and mucosal immune responses was better with IN delivery of a large volume. A small volume required multiple administrations and higher doses of antigen and adjuvant for equal results. This suggests that delivery of antigen to the lung and/or diges-tive system is superior to delivery to the nasal cavity. CONCLUSIONS: Our results suggest that the synergy between CpG ODN and native toxins (CT, LT) may depend on their enzymatic activity and that the lack of synergy with nontoxic derivatives (LTB, LTK63) arises, since they do not have enzymatic activity. Because both CT and LT are too toxic for use in humans, it is possible that CpG ODN may be combined with bacterial toxin mutants that retain some enzymatic activity to optimize immune augmentation.     

Influence of adjuvants in inducing immune responses to different epitopes included in a multiepitope,multivalent, multistage Plasmodium falciparum candidate vaccine (FALVAC-1) in outbred mice

FALVAC-1, a vaccine against Plasmodium falciparum was developed by joining 21 epitopes from P. falciparum vaccine antigens and an universal T helper epitope from tetanus toxoid. Since adjuvants influence different aspects of immune responses, in this study we investigated the effect of four adjuvants aluminum hydroxide (alum), nonionic copolymer adjuvant P1005 (water-in-oil emulsion), CpG oligodeoxynucleotides (ODN), and QS-21 in eliciting immune responses in outbred mice. QS-21 and copolymer adjuvants were the best formulations in inducing higher and long-lasting antibody titers to the whole vaccine compared to alum and CpG. QS-21 was the only adjuvant to elicit predominantly IgG2a response and antibodies reactive with all epitopes incorporated in the vaccine construct. Vaccine elicited antibodies recognized sporozoites and asexual blood-stage parasites. FALVAC-1 immunized mice induced lymphoproliferative and IFN-gamma response to the vaccine. QS-21 and CpG adjuvants were able to elicit T proliferative responses to 20 of the 22 epitopes in the vaccine. In conclusion, this study demonstrated that with suitable adjuvant such as QS-21, it is possible to elicit immune responses to most of the epitopes included in the FALVAC-1 vaccine.     

Amino acid substitutions at positions 122 and 145 of hepatitis B virus surface antigen (HBsAg) determine the antigenicity and immunogenicity of HBsAg and influence in vivo HBsAg clearance

A variety of amino acid substitutions, such as K122I and G145R, have been identified around or within the a determinant of hepatitis B surface antigen (HBsAg), impair HBsAg secretion and antibody binding, and may be responsible for immune escape in patients. In this study, we examined how different substitutions at amino acid positions 122 and 145 of HBsAg influence HBsAg expression, secretion, and recognition by anti-HBs antibodies. The results showed that the hydrophobicity, the presence of the phenyl group, and the charges in the side chain of the amino acid residues at position 145 reduced HBsAg secretion and impaired reactivity with anti-HBs antibodies. Only the substitution K122I at position 122 affected HBsAg secretion and recognition by anti-HBs antibodies. Genetic immunization in mice demonstrated that the priming of anti-HBs antibody response was strongly impaired by the substitutions K122I, G145R, and others, like G145I, G145W, and G145E. Mice preimmunized with wild-type HBsAg (wtHBsAg) or variant HBsAg (vtHBsAg) were challenged by hydrodynamic injection (HI) with a replication-competent hepatitis B virus (HBV) clone. HBsAg persisted in peripheral blood for at least 3 days after HI in mice preimmunized with vtHBsAg but was undetectable in mice preimmunized with wtHBsAg, indicating that vtHBsAgs fail to induce proper immune responses for efficient HBsAg clearance. In conclusion, the biochemical properties of amino acid residues at positions 122 and 145 of HBsAg have a major effect on antigenicity and immunogenicity. In addition, the presence of proper anti-HBs antibodies is indispensable for the neutralization and clearance of HBsAg during HBV infection.     

Neonatal DNA immunization with a plasmid encoding an internal viral protein is effective in the presence of maternal antibodies and protects against subsequent viral challenge.

Conventional vaccines are remarkably effective in adults but are much less successful in the very young, who are less able to initiate a mature immune response and who may carry maternal antibodies which inactivate standard vaccines. We set out to determine whether DNA immunization might circumvent these problems. We have previously shown that intramuscular injection of plasmid DNA encoding the nucleoprotein (NP) gene of lymphocytic choriomeningitis virus (LCMV) is capable of inducing immune responses and protecting 50% of adult mice against lethal and sublethal challenge with LCMV. Here we demonstrate that mouse pups injected with the same plasmid hours or days after birth produce major histocompatibility complex-restricted, NP-specific cytotoxic T lymphocytes (CTL) that persist into adulthood; 48% of vaccinated pups responded to subsequent sublethal viral challenge by the accelerated production of anti-NP LCMV-specific CTL, indicating that these animals had been successfully immunized by the plasmid DNA. In addition, these mice showed a >95% reduction in splenic viral titers 4 days postinfection compared to control mice, demonstrating a more rapid control of infection in vivo. Furthermore, pups born of and suckled on LCMV-immune dams (and therefore containing passively acquired anti-LCMV antibodies at the time of DNA inoculation) responded to the DNA vaccine in a similar manner, showing that maternally derived anti-LCMV antibodies do not significantly inhibit the generation of protective immune responses following DNA vaccination. These findings suggest that, at least in this model system, DNA immunization circumvents many of the problems associated with neonatal immunization.     

Oral immunization of mice with Japanese encephalitis virus envelope protein synthesized in Escherichia coli induces anti-viral antibodies

In order to evaluate the possibility of developing an oral vaccine against Japanese encephalitis virus (JEV), mice were fed with recombinant JEV envelope (E) protein synthesized in Escherichia coli. The protein was administered orally to mice with or without an immunostimulatory cytosine-phosphate-guanosine (CpG) motif containing synthetic oligodeoxynucleotide (ODN) as an adjuvant. The immunized mice made high-titered anti-E and anti-JEV antibodies. Mice immunized with JEV E protein along with the ODN adjuvant produced higher antibody titers and these were predominantly IgG2a type. These antibodies, however, failed to neutralize JEV activity in vitro, and the immunization did not protect the mice against lethal JEV challenge. Splenocytes from the immunized mice secreted large amounts of interferon (IFN)-gamma and showed proliferation in the presence of JEV E protein. Our results indicate that JEV E protein delivered orally to mice together with ODN generated both humoral and cellular immune responses to JEV, and these were of the Th1 type.     

乙型肝炎病毒全S基因疫苗诱导小鼠的特异性免疫应答

乙型肝炎病毒 (ＨＢＶ)感染是我国常见病及多发病。ＨＢＶ难以清除的原因之一就是机体的免疫功能障碍。目前虽然基因重组ＨＢＶ表面抗原 (ＨＢｓＡｇ)疫苗预防ＨＢＶ感染取得了较好的效果 ,但基因重组ＨＢｓＡｇ疫苗主要能诱导特异性体液免疫 ,不能刺激机体的细胞免疫应答。近年来发现基因疫苗可诱导机体产生细胞及体液免疫反应 ,特别是诱导细胞免疫反应的能力优于蛋白、多肽类疫苗 ,更适应于慢性病毒感染的预防与治疗[1,2 ] 。为了探讨应用ＨＢＶ基因疫苗预防ＨＢＶ感染的可能性 ,本文构建了ＨＢＶ全Ｓ基因和ＨＢｓＡｇ基因疫苗 ,观察和比…     

A combination of Flt3 ligand cDNA and CpG oligodeoxynucleotide as nasal adjuvant elicits protective secretory-IgA immunity to Streptococcus pneumoniae in aged mice

Our previous study showed that a combination of a plasmid-expressing Flt3 ligand (pFL) and CpG oligodeoxynucleotides (CpG ODN) as a combined nasal adjuvant elicited mucosal immune responses in aged (2-y-old) mice. In this study, we investigated whether a combination of pFL and CpG ODN as a nasal adjuvant for a pneumococcal surface protein A (PspA) would enhance PspA-specific secretory-IgA Ab responses, which could provide protective mucosal immunity against Streptococcus pneumoniae infection in aged mice. Nasal immunization with PspA plus a combination of pFL and CpG ODN elicited elevated levels of PspA-specific secretory-IgA Ab responses in external secretions and plasma in both young adult and aged mice. Significant levels of PspA-specific CD4(+) T cell proliferative and PspA-induced Th1- and Th2- type cytokine responses were noted in nasopharyngeal-associated lymphoreticular tissue, cervical lymph nodes, and spleen of aged mice, which were equivalent to those in young adult mice. Additionally, increased numbers of mature-type CD8, CD11b-expressing dendritic cells were detected in mucosal inductive and effector lymphoid tissues of aged mice. Importantly, aged mice given PspA plus a combination of pFL and CpG ODN showed protective immunity against nasal S. pneumoniae colonization. These results demonstrate that nasal delivery of a combined DNA adjuvant offers an attractive possibility for protection against S. pneumoniae in the elderly.     

Enhancement of CD8+ T cell immunity in the lung by CpG oligodeoxynucleotides increases protective efficacy of a modified vaccinia Ankara vaccine against lethal poxvirus infection even in a CD4-deficient host

Immunostimulatory CpG oligodeoxynucleotides (ODN) have proven effective as adjuvants for protein-based vaccines, but their impact on immune responses induced by live viral vectors is not known. We found that addition of CpG ODN to modified vaccinia Ankara (MVA) markedly improved the induction of longer-lasting adaptive protective immunity in BALB/c mice against intranasal pathogenic vaccinia virus (Western Reserve; WR). Protection was mediated primarily by CD8(+) T cells in the lung, as determined by CD8-depletion studies, protection in B cell-deficient mice, and greater protection correlating with CD8(+) IFN-gamma-producing cells in the lung but not with those in the spleen. Intranasal immunization was more effective at inducing CD8(+) T cell immunity in the lung, and protection, than i.m. immunization. Addition of CpG ODN increased the CD8(+) response but not the Ab response. Depletion of CD4 T cells before vaccination with MVA significantly diminished protection against pathogenic WR virus. However, CpG ODN delivered with MVA was able to substitute for CD4 help and protected CD4-depleted mice against WR vaccinia challenge. This study demonstrates for the first time a protective adjuvant effect of CpG ODN for a live viral vector vaccine that may overcome CD4 deficiency in the induction of protective CD8(+) T cell-mediated immunity.     

Tailoring Subunit Vaccine Immunity with Adjuvant Combinations and Delivery Routes Using the Middle East Respiratory Coronavirus (MERS-CoV) Receptor-Binding Domain as an Antigen

The development of an effective vaccine is critical for prevention of a Middle East respiratory syndrome coronavirus (MERS-CoV) pandemic. Some studies have indicated the receptor-binding domain (RBD) protein of MERS-CoV spike (S) is a good candidate antigen for a MERS-CoV subunit vaccine. However, highly purified proteins are typically not inherently immunogenic. We hypothesised that humoral and cell-mediated immunity would be improved with a modification of the vaccination regimen. Therefore, the immunogenicity of a novel MERS-CoV RBD-based subunit vaccine was tested in mice using different adjuvant formulations and delivery routes. Different vaccination regimens were compared in BALB/c mice immunized 3 times intramuscularly (i.m.) with a vaccine containing 10 µg of recombinant MERS-CoV RBD in combination with either aluminium hydroxide (alum) alone, alum and polyriboinosinic acid (poly I:C) or alum and cysteine-phosphate-guanine (CpG) oligodeoxynucleotides (ODN). The immune responses of mice vaccinated with RBD, incomplete Freund’s adjuvant (IFA) and CpG ODN by a subcutaneous (s.c.) route were also investigated. We evaluated the induction of RBD-specific humoral immunity (total IgG and neutralizing antibodies) and cellular immunity (ELISpot assay for IFN-γ spot-forming cells and splenocyte cytokine production). Our findings indicated that the combination of alum and CpG ODN optimized the development of RBD-specific humoral and cellular immunity following subunit vaccination. Interestingly, robust RBD-specific antibody and T-cell responses were induced in mice immunized with the rRBD protein in combination with IFA and CpG ODN, but low level of neutralizing antibodies were elicited. Our data suggest that murine immunity following subunit vaccination can be tailored using adjuvant combinations and delivery routes. The vaccination regimen used in this study is promising and could improve the protection offered by the MERS-CoV subunit vaccine by eliciting effective humoral and cellular immune responses.     

Intranasal immunization with CpG oligodeoxynucleotides as an adjuvant dramatically increases IgA and protection against herpes simplex virus-2 in the genital tract

Development of vaccines capable of preventing the transmission or limiting the severity of sexually transmitted viruses, such as HSV and HIV, will likely be dependent on the induction of potent long-lasting mucosal immune responses in the genital tract. Recently, synthetic oligodeoxynucleotides (ODN) containing immunostimulatory CpG motifs were shown to serve as potent adjuvants for the induction of mucosal immune responses. Here, we show that intranasal immunization with CpG ODN, plus recombinant glycoprotein B (rgB) of HSV-1, results in significantly elevated levels of specific anti-gB IgA Abs in vaginal washes that remained high throughout the estrous cycle. Additionally, dramatically elevated numbers of specific IgA Ab-secreting cells were present and persisted in the genital tract in response to intravaginal (IVAG) HSV-2 challenge. HSV-2-specific CTL were observed at moderate levels in the spleens of CpG or non-CpG ODN-immunized mice. In contrast, strong CTL responses were observed locally in the genital tissues of both groups following IVAG HSV-2 challenge. Interestingly, mice immunized intranasally with rgB plus CpG ODN, but not non-CpG ODN, were significantly protected following IVAG HSV-2 challenge. Measurement of virus in protected CpG-immunized mice revealed a log lower level of replication within the first few days after infection. In conclusion, these results indicate that intranasal immunization with CpG ODN plus protein mediates immunity in the female genital tract capable of protecting against a sexually transmitted pathogen.     

Immunostimulatory CpG motifs induce CTL responses to HIV type I oligomeric gp140 envelope protein

In the present study we investigated the immunomodulatory effects of two adjuvants, liposomal lipid A [L(LA)] and CpG-containing oligodeoxynucleotides (CpG ODN), to the HIV-1 ogp140 envelope protein. Administration of each of these adjuvants separately with unencapsulated ogp140 resulted in low antibody titres. Encapsulation of ogp140 in liposomes containing lipid A resulted in a sixfold increase in anti-ogp140 antibodies. The antibody titres were further enhanced threefold by the addition of CpG ODN. Priming and boosting BALB/c mice with unencapsulated ogp140 with L(LA) or encapsulation in liposomes containing lipid A induced a mixed Th1/Th2 type of immune response. In contrast, immunization with L(ogp140 + LA) plus CpG ODN switched the immune response to a Th-1 response with elevated anti-ogp140 IgG2a antibodies and IFN-gamma levels. Both adjuvants induced excellent ogp140-specific proliferative and CTL responses. Therefore, for the induction of high titre antibodies, but not for cellular responses, the antigen and lipid A have to be present in the same liposomes. These results can have significant implications in directing the Th1 or Th2 differentiation of antigen-specific immune responses in the context of vaccine development.     

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.     

Effects of multiple copies of CpG on DNA vaccination

It has previously been demonstrated that a dose-dependent enhancement of immune response is derived from immunization with several copies of the CpG motif. Following that lead, we sought to incorporate a higher copy number of CpG motifs into an expression construct to evaluate the augmentation of immune responses. By multiple insertions, 30 copies of the CpG motif were cloned into the backbone of an expression construct encoding the foot-and-mouth disease virus (FMDV) capsid protein VP1. After intramuscular immunization, an augmented immune response with significantly increased levels of the specific antibody, T-cell proliferation, and IFN-gamma in Balb/c mice was observed. Compared to chemically synthesized CpG ODN, application of such a multicopy of CpG sequences within the expression backbone for DNA vaccination strategy is feasible and warranted.     

Quantitation of Group-specificaAntigen in Hepatitis B Vaccines by Anti-HBs/aMonoclonal Antibody

Balb/c mice were immunized with aluminium hydroxide [alum, Al(OH)₃]-adjuvanted hepatitis B (HB) vaccines of subtypesadr,ayworadw. Spleen cells from the immune animals were fused with SP2/O cells. Eight hybridoma clones producing antibodies specific or HB surface antigen (HBsAg) were selected. Monoclonal antibodies (mAbs) of four clones were specific for group-specific antigen/a, and the other of four clones were specific for subtype antigen/d,y,r, orw. The anti-HBs/amAbs were classified into three non-competitive groups.Quantitation of group-specific determinantaof HBsAg (HBsAg/a) was performed by sandwich enzyme-linked immunosorbent assay (ELISA), in which a solid phase of anti-HBs guinea-pig polyclonal antibodies (pAb), the HBsAg for testing, anti-HBs/amouse mAb and horseradish peroxidase (HRP)-conjugated anti-mouse IgG were used.The unadsorbed HBsAg was used to establish the standard curve HBsAg/a. The lower detection limits were 0·5 to 1 ng/ml of HBsAg. Methods of solubilization of alum were investigated to quantify HBsAg/ain adsorbed HB vaccines. The recovery rate was more than 60% if vaccines were prediluted. The recovery of HBsAg/ain HB vaccines produced by the same manufacturer showed the similar recovery rate, and the contents of HBsAg/ain adsorbed HB vaccines could be estimated by the recovery rate determined for adsorbed HB vaccines.     

Leishmania donovani recombinant iron superoxide dismutase B1 protein in the presence of TLR-based adjuvants induces partial protection of BALB/c mice against Leishmania major infection

In this study, we tested the protective efficacy of recombinant Leishmania donovani iron superoxide dismutase B1 (SODB1) against Leishmania major infection in BALB/c mice. Mice were challenged with L. major 3weeks after the second boost immunization with rSODB1 alone or in the presence of adjuvants. Injection of BALB/c mice with rSODB1 alone elicited both humoral and cellular immune responses. Administration of rSODB1 with CpG ODN or GLA-SE (a synthetic toll-like receptor 4 agonist) adjuvant resulted in the induction of anti-SODB1 IgG1, and more importantly of significantly high levels of IgG2a isotype. Immunization of mice with rSODB1 alone or with adjuvant induced the production of IFN-γ by splenocytes in response to stimulation with L. major soluble leishmanial antigens (SLA). Moreover, immunization protocols involving rSODB1 resulted in a significant decrease in IL-10 as compared to controls. The presence of CpG ODN or GLA-SE adjuvant in the immunization protocols resulted in a relative increase in IFN-γ in response to stimulation with rSODB1 in comparison to immunization with rSODB1 alone. Mice immunized with rSODB1 plus CpG ODN or GLA-SE, were able to partially control their Leishmania infections, as indicated by the reduction in footpad swelling and parasite numbers, compared to controls. These results suggest that immunization with recombinant SODB1 protein together with CpG ODN or GLA-SE can be potential vaccine candidate against leishmaniasis.     

Immunization of Aged Pigs with Attenuated Pseudorabies Virus Vaccine Combined with CpG Oligodeoxynucleotide Restores Defective Th1 Immune Responses

Background and Aims

Attempts to immunize aged subjects often result in the failure to elicit a protective immune response. Murine model studies have shown that oligonucleotides containing CpG motifs (CpG ODN) can stimulate immune system in aged mice as effectively as in young mice. Since many physiological and pathophysiological data of pigs can be transferred to humans, research in pigs is important to confirm murine data. Here we investigated whether immunization of aged pig model with attenuated pseudorabies virus vaccine (PRV vaccine) formulated with CpG ODN could promote a successful development of immune responses that were comparable to those induced in young pigs in a similar manner.

Methodology

Young and aged pigs were immunized IM with PRV vaccine alone, or in combination with CpG ODN respectively. At days 3, 7, 14 post immunization sera were assayed by ELISA for IgG titres, at day 7 for IgG1 and IgG2 subtypes titres. All blood samples collected in evacuated test tubes with K-EDTA at day 7 were analyzed for flow cytometer assay. Blood samples at day 7 collected in evacuated test tubes with heparin were analysed for antigen-specific cytokines production and peripheral blood mononuclear cells (PBMCs) proliferative responses.

Results

CpG ODN could enhance Th1 responses (PRV-specific IgG2/IgG1 ratio, proliferative responses, Th1 cytokines production) when used as an adjuvant for the vaccination of aged pigs, which were correlated with enhanced CD4+ T cells percentage, decreased CD4+CD8+CD45RO+ T cells percentage and improved PRV-specific CD4+ T cells activation.

Conclusions

Our results demonstrate a utility for CpG ODN, as a safe vaccine adjuvant for promoting effective systemic immune responses in aged pig model. This agent could have important clinical uses in overcoming some of age-associated depressions in immune function that occur in response to vaccination.