Innate IL-10 promotes the induction of Th2 responses with plasmid DNA expressing HIV gp120

Like most DNA vaccines, intramuscular immunization with plasmid DNA coding for influenza virus haemagglutinin (HApDNA) induced Th1 responses and IgG2a antibodies in mice. However, plasmid DNA coding for HIV gp120 (gp120pDNA) induced Th2-biased responses and predominantly IgG1 antibodies. Responses to gp120pDNA switched to a Th1-type in IL-10-defective mice and to exclusively IgG2a antibodies in IL-4-defective mice. Conversely, antigen-specific IFN-gamma production induced by gp120pDNA or HApDNA was reduced in IL-12-defective mice, whereas addition of plasmid DNA coding for IL-12 enhanced Th1 responses. Plasmid DNA stimulated IL-10 and IL-12 production by macrophages and dendritic cells (DCs) in vitro and anti-IL-10 antibodies enhanced IL-12 production and DC maturation in response to gp120pDNA. Our findings suggest that T cell responses induced by DNA vaccines is influenced by the nature of the antigen, and that the induction of Th2-biased responses with gp120pDNA is mediated in part through the stimulation of innate IL-10, which inhibits activation of DCs that direct the induction of Th1 cells.     

Synthetic nanoparticle vaccines produced by layer-by-layer assembly of artificial biofilms induce potent protective T-cell and antibody responses in vivo

Nanoparticle vaccines induce potent immune responses in the absence of conventional adjuvant due to the recognition by immune cells of the particle structures, which mimic natural pathogens such as viruses and bacteria. Nanoparticle vaccines were fabricated by constructing artificial biofilms using layer-by-layer (LbL) deposition of oppositely charged polypeptides and target designed peptides on CaCO₃ cores. LbL nanoparticles were efficiently internalized by dendritic cells in vitro by a mechanism that was at least partially phagocytic, and induced DC maturation without triggering secretion of inflammatory cytokines. LbL nanoparticle delivery of designed peptides to DC resulted in potent cross-presentation to CD8+ T-cells and more efficient presentation to CD4+ T-cells compared to presentation of soluble peptide. A single immunization of mice with LbL nanoparticles containing designed peptide induced vigorous T-cell responses characterized by a balanced effector (IFNγ) and Th2 (IL-4) ELISPOT profile and in vivo CTL activity. Mice immunized with LbL nanoparticles bearing ovalbumin-derived designed peptides were protected from challenge with Listeria monocytogenes ectopically expressing ovalbumin, confirming the relevance of the CTL/effector T-cell responses. LbL nanoparticles also elicited antibody responses to the target epitope but not to the matrix components of the nanoparticle, avoiding the vector or carrier affect that hampers utility of other vaccine platforms. The potency and efficacy of LbL nanoparticles administered in aqueous suspension without adjuvant or other formulation additive, and the absence of immune responses to the matrix components, suggest that this strategy may be useful in producing novel vaccines against multiple diseases.     

Immunogenicity and efficacy of recombinant RSV-F vaccine in a mouse model

RSV vaccine development has constraints due to safety issues encountered by formalin-inactivated FI-RSV vaccines. A desirable vaccine should induce Th(1) responses and a strong mucosal immunity to provide complete protection from RSV infection. In the present paper, we developed and evaluated a mucosal vaccine against RSV in a mouse model. The antigenic regions corresponding to residues 412-524 of RSV-F protein were amplified by RT-PCR and cloned into a vector containing the ctxA(2)B gene of the cholera toxin. The recombinant protein was expressed in E. coli and properties of the recombinant protein were analyzed by SDS-PAGE, Western blot and G(M1)-ELISA. The purified recombinant protein (rRF-412) was used to immunize BALB/c mice intranasally. The results from our studies show that the rRF-412 immunogen induced mucosal (IgA) and systemic antibody (IgG, IgG1, IgG2a, and IgG2b) responses which neutralized RSV. The IgG1/IgG2a ratios indicated a Th(1)-biased antibody response. The Th(1) (TNF-alpha, IL-12p70, IFN-gamma, IL-2) and Th(2) (IL-10, IL-4 and IL-5) cytokine profiles were analyzed after stimulation of spleen cells from mice immunized with purified RF-412 protein. Similar to the antibody response, we observed that the rRF-412 immunogen induced a mixed Th(1)/Th(2) cytokine immune response with a Th(1)-bias response. Serum antibodies were capable of neutralizing RSV and mice immunized with rRF-412 were significantly protected from live RSV challenge. Our data provides evidence that the rRF-412 immunogen may be a potential mucosal vaccine candidate against RSV.     

Modulation of the infant immune responses by the first pertussis vaccine administrations

Many efforts are currently made to prepare combined vaccines against most infectious pathogens, that may be administered early in life to protect infants against infectious diseases as early as possible. However, little is known about the general immune modulation induced by early vaccination. Here, we have analyzed the cytokine secretion profiles of two groups of 6-month-old infants having received as primary immunization either a whole-cell (Pw) or an acellular (Pa) pertussis vaccine in a tetravalent formulation of pertussis-tetanus-diphtheria-poliomyelitis vaccines. Both groups of infants secreted IFN-gamma in response to the Bordetella pertussis antigens filamentous haemagglutinin and pertussis toxin, and this response was correlated with antigen-specific IL-12p70 secretion, indicating that both pertussis vaccines induced Th1 cytokines. However, Pa recipients also developed a strong Th2-type cytokine response to the B. pertussis antigens, as noted previously. In addition, they induced Th2-type cytokines to the co-administrated antigen tetanus toxo?d, as well as to the food antigen beta-lactoglobulin. Furthermore, the general cytokine profile of the Pa recipients was strongly Th2-skewed at 6 months, as indicated by the cytokines induced by the mitogen phytohaemagglutinin. These data demonstrate that the cytokine profile of 6-month-old infants is influenced by the type of formulation of the pertussis vaccine they received at 2, 3 and 4 months of life. Large prospective studies would be warranted to evaluate the possible long-term consequences of this early modulation of the cytokine responses in infants.     

Using bicistronic IL-4 reporter mice to identify IL-4 expressing cells following immunisation with aluminium adjuvant

The Th2 dominated immune response induced by aluminium adjuvants remains a major limitation to their application to modern vaccines. Previous studies have shown that while these adjuvants can initiate Th2 responses in mice with disrupted IL-4 production or IL-4 signalling, a strong Th1 response becomes evident in these situations, suggesting that the main function of IL-4 in the response to aluminium adsorbed antigens is to antagonise Th1 induction. In this study we have employed the recently described, 4get reporter mice, that express GFP as part of a bicistronic IL-4-IRES-GFP mRNA, to identify IL-4 expressing cells in situ during an aluminium adjuvant-induced Th2 responses. These preliminary studies implicate conventional CD4+ T cells as the sole potential producers of IL-4 following immunisation with antigen prepared in aluminium adjuvants. Furthermore, as GFP positive cells are first detected in the lymph node, our studies indicate that these cells may act to block induction of Th1 responses by aluminium adjuvants. We conclude that devising strategies to block the effects of IL-4 production by these cells will facilitate the rational design of vaccine adjuvants that induce Th1 responses.     

Pulmonary CD4+ cytokine responses in mice reveal differences in the relative immunogenicity of cold-adapted influenza A vaccine donor strains

We previously described differences in the 50% protective dose and isotype-specific antibody secreting cell (ASC) responses to US and Russian influenza A cold-adapted (ca) donor strains in the lungs of BALB/c mice [Wareing MD, Watson JM, Brooks MJ, Tannock GA. Immunogenic and isotype-specific responses to Russian and US cold-adapted influenza A vaccine donor strains A/Leningrad/134/17/57, A/Leningrad/134/47/57, and A/Ann Arbor/6/60 (H2N2) in mice. J Med Virol 2001;65(1):171-7]. A/Leningrad/134/17/57(Len/17-ca) was shown to be a superior immunogen to A/Leningrad/134/47/57-ca (Len/47-ca), which, in turn, was superior to A/Ann Arbor/6/60-ca (AA-ca) but no other comparative data exist. In order to extend our findings and determine a means for selecting the most immunogenic ca influenza A vaccine, the intracellular cytokine responses by CD4+ and CD8+ T cells to AA-ca, Len/47-ca and Len/17-ca and their respective wild-type parental viruses were compared in mice. Day 5 after infection with Len/17-ca, when levels of IL-2, -4 and -10 were highest in the mediastinal lymph nodes (MLN) and lungs, was chosen as the optimum time to harvest lymphocytes and 72 h was determined to be the optimum re-stimulation period for lymphocytes by APCs. Under these conditions, the frequency of CD4+ and CD8+ cells expressing cytokines was highest in the lungs compared with the MLN. A dominant IL-6 response was induced, although all virus strains induced a Th1/Th2 cytokine profile. While the CD8+ cytokine response appeared non-specific, the cytokine response elicited in the lungs by CD4+ cells to Len/17-ca-inoculation was greater than that induced by Len/47-ca, or AA/ca. The CD4+ cytokine response in the lungs may be a useful measure of immunogenicity to determine the most effective influenza reassortant for inclusion in vaccines.     

Enhanced humoral and cell-mediated immune responses after immunization with trivalent influenza vaccine adjuvanted with cationic liposomes

The recent pandemic caused by new influenza A (H1N1) has emphasized the need for improved influenza vaccines with enhanced immune responses that ideally include longlived humoral and CMI responses and mediate a broad protection. This study demonstrates that administration of trivalent influenza vaccine (TIV) with the cationic liposome adjuvant system CAF01 enhances the humoral immune response as measured by hemagglutinin inhibition titers and influenza-specific serum antibody titers, and promote a strong Th1 response with augmented levels of IL-1β, IL-2, IL-12, IFN-γ and TNF-α. Furthermore, high levels of IL-17 are detected in agreement with CAF01's ability to promote TH17 responses. Importantly, the Th1/Th17 cytokine profile is still maintained 20 weeks after the last vaccination. The CAF01 adjuvanted influenza vaccine reduces weight loss and temperature decrease and results in complete survival of mice challenged with the drifted H1N1 influenza strain A/PR/8/34. Overall, the results suggest that CAF01 is a potent adjuvant system for future, improved influenza vaccines.     

Cytokine mRNAs in the nasal-associated lymphoid tissue during influenza virus infection and nasal vaccination

Intranasal immunization with a current inactivated influenza vaccine together with an adjuvant (cholera toxin B subunit supplemented with a trace amount of whole toxin, CTB*) was confirmed in BALB/c mice to mimic influenza virus (A/PR/8/34, H1N1) infection with respect to mucosal IgA antibody responses, in which IgA antibody-forming cell responses in the nasal-associated lymphoid tissue (NALT) were involved with a peak around 7 days after infection or vaccination. Next, the expression of various cytokine mRNAs in the NALT was compared in mice either infected with viruses or immunized with CTB*-combined vaccine, to examine Th cell and cytokine regulation of mucosal IgA antibody responses. In infected mice, strong IL-2, weak IL-4, strong IL-6 and strong IFN-gamma mRNA expressions were induced during early days of infection; especially, IFN-gamma mRNA was expressed by both CD4(+) and CD8(+) T cells around 7 days after infection. In mice given CTB*-combined vaccine, weak IL-2, strong IL-4, strong IL-6 and weak IFN-gamma mRNA expressions were induced during early days of vaccination; especially, IL-4 mRNA was expressed by CD4(+) T cells. Thus, IL-6 mRNAs were expressed strongly in both infected and vaccinated mice. The IFN-gamma-rich cytokine mRNA profiles in the infected mice were reflected upon serum IgG2a-rich Ab responses, while the IL-4-rich profiles in the vaccinated mice were reflected upon the IgG1-rich Ab responses. Thus, influenza virus infection and CTB*-combined nasal vaccine induced Th1 dominant and Th2 dominant cytokine profiles, respectively, while the similarity of mucosal IgA antibody responses between infection and vaccination could be explained by the appearance of IL-6 mRNAs.     

A novel influenza subunit vaccine composed of liposome-encapsulated haemagglutinin/neuraminidase and IL-2 or GM-CSF. II. Induction of TH1 and TH2 responses in mice

This study was aimed at analyzing, in parallel, the humoral and cellular immune responses elicited in mice immunized with liposomal influenza A (Shangdong/9/93) subunit vaccines composed of haemagglutinin/neuraminidase (H3N2) and IL-2 or GM-CSF. Recently, we reported that such vaccines evoke a more rapid, stronger and longer-lasting (over 1 year) humoral response, as well as protective immunity against viral infection, following a single administration, as compared with the response induced by the free antigen given alone or together with soluble cytokines. In the present study, BALB/C mice were immunized once, i.p., s.c., i.m. or i.n., with nonliposomal or liposomal vaccines and the humoral (antibody titer and isotypes) and cellular (DTH, cytotoxicity, cytokine production) responses were assessed at various times (2-56 weeks). The main findings were: (a) the combined liposomal vaccines consisting of encapsulated antigen and encapsulated cytokine, but not the free antigen, elicited a high titer of serum IgG1, IgG2a, IgG3 and IgM antibodies; (b) the combined liposomal vaccines were efficient following administration by the various routes, and induced a local (in lung) IgA response in i.n. vaccinated mice; (c) the liposomal vaccines triggered DTH and cytotoxic responses, as well as cytokine (mainly IL-4) production. Together, these and other findings indicate that our cytokine-supported liposomal influenza vaccines efficiently stimulate both Th1 and Th2 responses and that such vaccines may be more potent in high-risk groups than the currently used subunit vaccines.     

J-LEAPS vaccines initiate murine Th1 responses by activating dendritic cells

The Ligand Epitope Antigen Presentation System (LEAPS) converts a peptide containing a T cell epitope as small as 8 amino acids into an immunogen and directs the nature of the subsequent response. Tandem synthesis of the J peptide (a peptide from the beta-2-microglobulin) with peptides of 15 or 30 amino acids from HSV-1 or HIV made them immunogenic and promoted Th1 immune responses. Immunization of A/J or C57BL/6 mice with J-LEAPS heteroconjugates containing an epitope from the HSV-1 glycoprotein D (JgD) or an epitope from the HIV gag protein (JH) emulsified with Seppic ISA51 induced increased levels of IL-12p70 by day 3 and increased levels of interferon gamma (IFN-gamma) on days 10 and 24. Interestingly, levels of IL-10, TNF-alpha, and IL-6 did not change. Neither the H nor the gD peptides alone elicited responses and only weak responses followed immunization with the J peptide. Bone marrow (BM) cells became CD86 and CD11c positive within 48 h of treatment with JgD or JH. JH or JgD treatment promoted IL-12p70 production and expression of CD8 denoting the maturation and activation of a subclass of myeloid DCs. Pure cultures of immature myeloid DCs also responded to JgD treatment, forming clusters, developing dendrites, and producing IL-12p70 within 24 h. The JH or JgD treated bone marrow cells (JgD-DC) were necessary and sufficient to activate splenic T cells to produce IFN-gamma and the JgD-DC provided an antigen specific booster response to T cells from JgD immunized mice. Adoptive transfer of JgD-DC was also sufficient to initiate protective antigen specific immunity from lethal challenge with HSV-1. The J-LEAPS vaccines appear to act as an adjuvant and immunogen on DC precursors in a unique manner to promote activation and maturation into IL-12p70 producing DCs which then can initiate sufficient Th1 immune responses to elicit protection without production of acute phase cytokines.     

Plasmodium falciparum apical membrane antigen 1 vaccine elicits multifunctional CD4 cytokine-producing and memory T cells

The Plasmodium falciparum apical membrane antigen 1 (AMA1) is a leading vaccine candidate and was tested for safety and immunogenicity in human Phase I Clinical Trials. PBMC from vaccine recipients were analyzed by flow cytometric methods to determine the nature of T-cell responses and AMA1-reactive memory T cells. Both CD4 and CD8 T cells produced a number of cytokines following AMA1 re-stimulation, with IL-5-producing cells at the highest frequency, consistent with a Th2 bias. The relative frequency of multifunctional cells synthesizing Th1 cytokines IFN-γ, IL-2 and TNF-α changed after each vaccination. Interestingly, median fluorescence intensity measurements revealed that cells producing more than one cytokine contributed greater quantities of each cytokine than cell populations that produced each of the cytokines alone. AMA1 vaccination also elicited the development of memory cell populations, and both central and effector memory T cells were identified concurrently after the AMA1 vaccination. The detailed profile of multifunctional T-cell responses to AMA1 presented here will advance our ability to assess the immunogenicity of human malarial vaccines.     

Baculovirus vectors expressing F proteins in combination with virus-induced signaling adaptor (VISA) molecules confer protection against respiratory syncytial virus infection

Baculovirus has been exploited for use as a novel vaccine vector. To investigate the feasibility and efficacy of recombinant baculoviruses (rBVs) expressing respiratory syncytial virus (RSV) fusion (F) proteins, four constructs (Bac-tF/64, Bac-CF, Bac-CF/tF64 and Bac-CF/tF64-VISA) were generated. Bac-tF64 displays the F ectodomain (tF) on the envelope of rBVs, whereas Bac-CF expresses full-length F protein in transduced mammalian cells. Bac-CF/tF64 not only displays tF on the envelope but also expresses F in cells. Bac-CF/tF64-VISA comprises Bac-CF/tF64 harboring the virus-induced signaling adaptor (VISA) gene. After administration to BALB/c mice, all four vectors elicited RSV neutralizing antibody (Ab), systemic Ab (IgG, IgG1, and IgG2a), and cytokine responses. Compared with Bac-tF64, mice inoculated with Bac-CF and Bac-CF/tF64 exhibited an increased mixed Th1/Th2 cytokine response, increased ratios of IgG2a/IgG1 antibody responses, and reduced immunopathology upon RSV challenge. Intriguingly, co-expression of VISA reduced Th2 cytokine (IL-4, IL-5, and IL-10) production induced by Bac-CF/tF64, thus relieving lung pathology upon a subsequent RSV challenge. Our results indicated that the Bac-CF/tF64 vector incorporated with the VISA molecule may provide an effective vaccine strategy for protection against RSV.     

Comparison of phage pVIII and KLH as vector in inducing the production of cytokines in C57BL/6J mice

We have demonstrated that phage display Candida albicans (C. albicans) LKVIRK epitope was protective in systemically infected C57BL/6J mice. The different development from precursor Ths, Th1 or Th2, will result in a protective or nonprotective immune response. To compare the types of cytokines induced by biologically and chemically synthesized vectors, C57BL/6J mice were immunized with hybrid phage displaying the epitope of LKVIRK and by synthesized peptide epitope LKVIRKNIVKKMIE conjugated through cysteine to keyhole limpet haemocyanin (KLH). The production of cytokines in spleens of immunized mice and in splenocytes culture supernatants stimulated by homologous immunogen in vitro was studied by RT-PCR and quantitative sandwich ELISA. The results showed that, compared to Tris-EDTA buffer (TE, 1 mM Tris, 0.1 mM EDTA, pH 8.0) injected mice, the expressions of Th1 type cytokine IFN-gamma, IL-2 and IL-12 were increased in hybrid phage, KLH-C, and wild phage immunized mice, and there were no differences between mice immunized with hybrid phage and KLH-C. While the expression of Th2 type cytokine IL-10 was similar in all mice, IL-4 was not detected. We obtained the same results in mRNA and protein level. These findings indicated that as carriers, phage and KLH were similar in inducing the Th1 type cytokines expression. Comparing to peptide synthesis couple with a carrier protein for injection, phage may be an inexpensive and simple route to the production of effective vaccines.     

PLGA-encapsulation of the Pseudomonas aeruginosa PopB vaccine antigen improves Th17 responses and confers protection against experimental acute pneumonia

The Pseudomonas aeruginosa type III secretion system protein PopB and its chaperon protein PcrH, when co-administered with the adjuvant curdlan, elicit Th17 responses after intranasal immunization of mice. These PopB/PcrH-curdlan vaccines protect mice against acute lethal pneumonia in an IL-17-dependent fashion involving CD4 helper T cells secreting IL-17 (Th17 cells). In this study, we tested whether encapsulation of PopB/PcrH in poly-lactic-co-glycolic acid (PLGA) nanoparticles could elicit Th17 responses to PopB. Recombinant PopB/PcrH or PcrH alone was encapsulated into PLGA nanoparticles. Mice (FVB/N) were intranasally immunized with the PLGA-PopB/PcrH nanoparticles, PLGA-PcrH nanoparticles, PLGA alone, or PopB/PcrH alone. The protective efficacy was assessed in an acute lung infection model with a lethal dose of an ExoU-producing version of P. aeruginosa strain PAO1. Th17 responses were assayed by intracellular flow cytometry and by ELISA for IL-17 in supernatants of splenocytes co-cultured with purified PopB/PcrH. PLGA-PopB/PcrH-immunized mice showed 3–4-fold higher Th17 responses both in the lung and in the spleen compared to mice immunized with empty PLGA or PopB/PcrH alone. After challenge with P. aeruginosa, PLGA-PopB/PcrH-immunized mice showed significantly lower bacterial counts in the lungs and improved survival. In conclusion, encapsulation of PopB/PcrH in PLGA nanoparticles can elicit Th17 responses to intranasal vaccination and protect mice against acute lethal P. aeruginosa pneumonia.     

COVID-19 adenovirus vector vaccine induces higher interferon and pro-inflammatory responses than mRNA vaccines in human PBMCs,macrophages and moDCs

BackgroundDuring the COVID-19 pandemic multiple vaccines were rapidly developed and widely used throughout the world. At present there is very little information on COVID-19 vaccine interactions with primary human immune cells such as peripheral blood mononuclear cells (PBMCs), monocyte-derived macrophages and dendritic cells (moDCs).MethodsHuman PBMCs, macrophages and moDCs were stimulated with different COVID-19 vaccines, and the expression of interferon (IFN-λ1, IFN-α1), pro-inflammatory (IL-1β, IL-6, IL-8, IL-18, CXCL-4, CXCL-10, TNF-α) and Th1-type cytokine mRNAs (IL-2, IFN-γ) were analyzed by qPCR. In addition, the expression of vaccine induced spike (S) protein and antiviral molecules were studied in primary immune cells and in A549 lung epithelial cells.ResultsAdenovirus vector (Ad-vector) vaccine AZD1222 induced high levels of IFN-λ1, IFN-α1, CXCL-10, IL-6, and TNF-α mRNAs in PBMCs at early time points of stimulation while the expression of IFN-γ and IL-2 mRNA took place at later times. AZD1222 also induced IFN-λ1, CXCL-10 and IL-6 mRNA expression in monocyte-derived macrophages and DCs in a dose-dependent fashion. AZD1222 also activated the phosphorylation of IRF3 and induced MxA expression. BNT162b2 and mRNA-1273 mRNA vaccines failed to induce or induced very weak cytokine gene expression in all cell models. None of the vaccines enhanced the expression of CXCL-4. AZD1222 and mRNA-1273 vaccines induced high expression of S protein in all studied cells.ConclusionsAd-vector vaccine induces higher IFN and pro-inflammatory responses than the mRNA vaccines in human immune cells. This data shows that AZD1222 readily activates IFN and pro-inflammatory cytokine gene expression in PBMCs, macrophages and DCs, but fails to further enhance CXCL-4 mRNA expression.     

Intramuscular Matrix-M-adjuvanted virosomal H5N1 vaccine induces high frequencies of multifunctional Th1 CD4 cells and strong antibody responses in mice

Ideally, a candidate pandemic influenza vaccine should elicit rapid and strong cell-mediated and humoral immune responses, which are long-lasting and exhibit broad cross-reactivity against drifted strains. The present study investigated the detailed humoral and cellular immune responses in mice vaccinated intranasally or intramuscularly with inactivated influenza H5N1 (NIBRG-14) virosomal vaccine alone or formulated with Matrix-M adjuvant. The intramuscular Matrix-M-adjuvanted vaccine induced a strong immediate and long-term humoral immune response with high cross-reactivity against drifted H5N1 viruses and showed a dose-sparing potential. Additionally, the vaccine induced a balanced Th1/Th2 cytokine profile and most importantly high frequencies of multifunctional Th1 CD4⁺ cells. Our results highlight that Matrix-M adjuvant is a promising parenteral adjuvant for formulating pandemic candidate vaccines.     

Immunization with PCEP microparticles containing pertussis toxoid, CpG ODN and a synthetic innate defense regulator peptide induces protective immunity against pertussis

We investigated the efficacy of a novel microparticle (MP) based vaccine formulation consisting of pertussis toxoid (PTd), polyphosphazene (PCEP), CpG ODN 10101 and synthetic cationic innate defense regulator peptide 1002 (IDR) against Bordetella pertussis in mice. We studied whether encapsulation of these IDR-CpG ODN complexes into polyphosphazene-based microparticles further enhanced their immunomodulatory activity compared to soluble formulations containing PCEP (SOL), or without PCEP (AQ). In vitro stimulation of murine macrophages showed MP induced significantly higher levels of pro-inflammatory cytokines. When assessed in a B. pertussis infection challenge model, a single immunization with MP formulation led to significantly lower bacterial loads compared to other formulations and non-vaccinated animals. ELISPOT of splenocytes showed that MP group mice had significantly higher number of antigen-specific IL-17 secreting cells. The cytokine profile in lung homogenates of MP group mice after challenge showed significantly higher amounts of MCP-1, TNF-α, IFN-γ, IL-12 and IL-17 and significantly lowered IL-10 levels suggesting a strong Th1 shift. Protection was observed against challenge infection with B. pertussis. On the other hand protective immune responses elicited in Quadracel^® immunized mice were Th2 skewed. Hence, we conclude that formulation of PTd, PCEP, CpG ODN and IDR into MP generates a protective immune response in mice against pertussis emphasizing the potential of MP as a delivery vehicle for the potential development of single-shot vaccines.     

The Rb1 fraction of ginseng elicits a balanced Th1 and Th2 immune response

Porcine parvovirus (PPV) vaccines containing different adjuvants were evaluated for inducing Th1 or Th2 type of immunity in mice. Isotypes of antigen specific antibodies and levels of cytokines in serum and in lymphocyte culture supernatants measured by ELISA and the Gyrolab Bioaffy were used to determine the polarisation of the immune response. Enumeration of cytokine secreting cells was carried out by ELISPOT assays. Vaccines containing the ginseng-fraction Rb1 induced serum-detectable amounts of IL-4 and IL-10 as early as 24h after primary injection that was confirmed in sera collected at 24 and 72 h post re-vaccination. Five weeks after booster, immune lymphocytes were still producing large amounts of cytokines including IFN-gamma, IL-2, IL-4, IL-10 and TNF-alpha and the antibody titres were still similar to those titres recorded 1 week post booster. The Rb1 adjuvanted vaccines stimulated similar titres of antigen specific IgG1, IgG(2a) and IgG(2b). Thus, the cytokine and the serological data indicated that the Rb1 fraction of ginseng elicits a balanced Th1 and Th2 immune response.     

An epitope-specific DerG-PG70 LEAPS vaccine modulates T cell responses and suppresses arthritis progression in two related murine models of rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune joint disease maintained by aberrant immune responses involving CD4+ T helper (Th)1 and Th17 cells. In this study, we tested the therapeutic efficacy of Ligand Epitope Antigen Presentation System (LEAPS™) vaccines in two Th1 cell-driven mouse models of RA, cartilage proteoglycan (PG)-induced arthritis (PGIA) and PG G1-domain-induced arthritis (GIA). The immunodominant PG peptide PG70 was attached to a DerG or J immune cell binding peptide, and the DerG-PG70 and J-PG70 LEAPS vaccines were administered to the mice after the onset of PGIA or GIA symptoms. As indicated by significant decreases in visual and histopathological scores of arthritis, the DerG-PG70 vaccine inhibited disease progression in both PGIA and GIA, while the J-PG70 vaccine was ineffective. Splenic CD4+ cells from DerG-PG70-treated mice were diminished in Th1 and Th17 populations but enriched in Th2 and regulatory T (Treg) cells. In vitro spleen cell-secreted and serum cytokines from DerG-PG70-treated mice demonstrated a shift from a pro-inflammatory to an anti-inflammatory/regulatory profile. DerG-PG70 peptide tetramers preferentially bound to CD4+ T-cells of GIA spleen cells. We conclude that the DerG-PG70 vaccine (now designated CEL-4000) exerts its therapeutic effect by interacting with CD4+ cells, which results in an antigen-specific down-modulation of pathogenic T-cell responses in both the PGIA and GIA models of RA. Future studies will need to determine the potential of LEAPS vaccination to provide disease suppression in patients with RA.     

Evaluation of the immunogenicity of pBudCE4.1 plasmids encoding mycolyl-transferase Ag85A and phosphate transport receptor PstS-3 from Mycobacterium tuberculosis

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb), remains a major health problem. The only currently available vaccine, BCG, confers only variable protection and an improved vaccine is urgently needed. Administration of DNA vaccines encoding the secreted mycolyl-transferase Ag85A and the surface-exposed phosphate transport receptor PstS-3 elicit an immune response capable of protecting mice challenged with Mtb. In order to combine the protection against Mtb infection induced by these two DNA vaccines, we have cloned Ag85A and PstS-3 in pBudCE4.1 vector, in which antigenic expression is controlled by two independent promoters. (BALB/cxC57BL/6)F1 mice were vaccinated with this combination vaccine and immune responses were compared to those induced by vaccination with plasmids encoding the single antigens on pBudCE4.1 or pV1J.ns-tPA backbone. Antibody and Th1 type cytokine responses against Ag85A were comparable, whereas responses against PstS-3 were clearly lower in mice vaccinated with the combination plasmid, suggesting antigenic competition with the mycolyl-transferase being the dominant antigen.