Elicitation Of Immune Responses Research Articles

Galectin-8 activates dendritic cells and stimulates antigen-specific immune response elicitation.

Galectin-8 (Gal-8) is a mammalian β-galactoside-binding lectin, endowed with proinflammatory properties. Given its capacity to enhance antigen-specific immune responses in vivo, we investigated whether Gal-8 was also able to promote APC activation to sustain T cell activation after priming. Both endogenous [dendritic cells (DCs)] and bone marrow-derived DCs (BMDCs) treated with exogenous Gal-8 exhibited a mature phenotype characterized by increased MHC class II (MHCII), CD80, and CD86 surface expression. Moreover, Gal-8-treated BMDCs (Gal-8-BMDCs) stimulated antigen-specific T cells more efficiently than immature BMDCs (iBMDCs). Proinflammatory cytokines IL-3, IL-2, IL-6, TNF, MCP-1, and MCP-5, as well as growth factor G-CSF, were augmented in Gal-8-BMDC conditioned media, with IL-6 as the most prominent. Remarkably, BMDCs from Gal-8-deficient mice (Lgals8-/- BMDC) displayed reduced CD86 and IL-6 expression and an impaired ability to promote antigen-specific CD4 T cell activation. To test if Gal-8-induced activation correlates with the elicitation of an effective immune response, soluble Gal-8 was coadministrated with antigen during immunization of BALB/cJ mice in the experimental foot-and-mouth disease virus (FMDV) model. When a single dose of Gal-8 was added to the antigen formulation, an increased specific and neutralizing humoral response was developed, sufficient to enhance animal protection upon viral challenge. IL-6 and IFN-γ, as well as lymphoproliferative responses, were also incremented in Gal-8/antigen-immunized animals only at 48 h after immunization, suggesting that Gal-8 induces the elicitation of an inflammatory response at an early stage. Taking together, these findings argue in favor of the use of Gal-8 as an immune-stimulator molecule to enhance the adaptive immune response.

Sugar or Fat?-Metabolic Requirements for Immunity to Viral Infections.

The realization that an intricate link exists between the metabolic state of immune cells and the nature of the elicited immune responses has brought a dramatic evolution to the field of immunology. We will focus on how metabolic reprogramming through the use of glycolysis and fatty-acid oxidation (sugar or fat) regulates the capacity of immune cells to mount robust and effective immune responses. We will also discuss how fine-tuning sugar and fat metabolism may be exploited as a novel immunotherapeutic strategy to fight viral infections or improve vaccine efficacy.

Colony Stimulating Factor-1 Receptor Expressing Cells Infiltrating the Cornea Control Corneal Nerve Degeneration in Response to HSV-1 Infection.

PurposeHerpes simplex virus type-1 (HSV-1) is a leading cause of neurotrophic keratitis, characterized by decreased or absent corneal sensation due to damage to the sensory corneal innervation. We previously reported the elicited immune response to infection contributes to the mechanism of corneal nerve regression/damage during acute HSV-1 infection. Our aim is to further establish the involvement of infiltrated macrophages in the mechanism of nerve loss upon infection.MethodsMacrophage Fas-Induced Apoptosis (MAFIA) transgenic C57BL/6 mice were systemically treated with AP20187 dimerizer or vehicle (VEH), and their corneas, lymph nodes, and blood were assessed for CD45+CD11b+GFP+ cell depletion by flow cytometry (FC). Mice were ocularly infected with HSV-1 or left uninfected. At 2, 4, and/or 6 days post infection (PI), corneas were assessed for sensitivity and harvested for FC, nerve structure by immunohistochemistry, viral content by plaque assay, soluble factor content by suspension array, and activation of signaling pathways by Western blot analysis. C57BL6 mice were used to compare to the MAFIA mouse model.ResultsMAFIA mice treated with AP20187 had efficient depletion of CD45+CD11b+GFP+ cells in the tissues analyzed. The reduction of CD45+CD11b+GFP+ cells recruited to the infected corneas of AP20187-treated mice correlated with preservation of corneal nerve structure and function, decreased protein concentration of inflammatory cytokines, and decreased STAT3 activation despite no changes in viral content in the cornea compared to VEH-treated animals.ConclusionsOur results suggest infiltrated macrophages are early effectors in the nerve regression following HSV-1 infection. We propose the neurodegeneration mechanism involves macrophages, local up-regulation of IL-6, and activation of STAT3.

The combination of recombinant and non-recombinant Bacillus subtilis spore display technology for presentation of antigen and adjuvant on single spore

BackgroundBacillus subtilis spores can be used for presentation of heterologous proteins. Two main approaches have been developed, the recombinant one, requiring modification of bacterial genome to express a protein of interest as a fusion with spore-coat protein, and non-recombinant, based on the adsorption of a heterologous protein onto the spore. So far only single proteins have been displayed on the spore surface.ResultsWe have used a combined approach to adsorb and display FliD protein of Clostridium difficile on the surface of recombinant IL-2-presenting spores. Such spores presented FliD protein with efficiency comparable to FliD-adsorbed spores produced by wild-type 168 strain and elicited FliD-specific immune response in intranasally immunized mice.ConclusionsOur results indicate that such dual display technology may be useful in creation of spores simultaneously presenting adjuvant and antigen molecules. Regarding the characteristics of elicited immune response it seems plausible that such recombinant IL-2-presenting spores with adsorbed FliD protein might be an interesting candidate for vaccine against infections with Clostridium difficile.

Male genital tract immune response against Chlamydia trachomatis infection.

Chlamydia trachomatis is the most commonly reported agent of sexually transmitted bacterial infections worldwide. This pathogen frequently leads to persistent, long-term, subclinical infections, which in turn may cause severe pathology in susceptible hosts. This is in part due to the strategies that Chlamydia trachomatis uses to survive within epithelial cells and to evade the host immune response, such as subverting intracellular trafficking, interfering signaling pathways and preventing apoptosis. Innate immune receptors such as toll-like receptors expressed on epithelial and immune cells in the genital tract mediate the recognition of chlamydial molecular patterns. After bacterial recognition, a subset of pro-inflammatory cytokines and chemokines are continuously released by epithelial cells. The innate immune response is followed by the initiation of the adaptive response against Chlamydia trachomatis, which in turn may result in T helper 1-mediated protection or in T helper 2-mediated immunopathology. Understanding the molecular mechanisms developed by Chlamydia trachomatis to avoid killing and host immune response would be crucial for designing new therapeutic approaches and developing protective vaccines. In this review, we focus on chlamydial survival strategies and the elicited immune responses in male genital tract infections.

Effective antigen delivery via dual entrapment in erythrocytes and autologous plasma beads

Fibrin-based polymeric systems have now emerged as efficient carriers of drugs, growth factors, genes, and cells. Earlier, we have reported fibrin-based plasma beads (PB), prepared from clotted whole plasma, as an efficient system for the controlled release of entrapped therapeutics. In the present study, we investigate the dual entrapment in erythrocytes and PB, as potential particulate antigen delivery system in rabbit and mice, with yeast invertase as the model antigen. Preparations used for immunisation include- invertase entrapped in erythrocytes, the same further entrapped in PB, and crosslinked with glutaraldehyde. While route of administration of the antigen only moderately affected the antibody titres, strategies slowing its release from PB increased the antibody titres remarkably, especially after a booster. Entrapment of erythrocytes entrapped antigen in the PB and further crosslinking with glutaraldehyde also resulted in significant alterations of IgG1/IgG2a ratio, indicating a shift towards humoral response. The elicited immune response was more marked in rabbits as compared to that in mice. Considering the well-known toxicity of the adjuvant, comparable antibody titres induced by the erythrocyte-plasma bead system was encouraging in the induction of humoral immunity.

ChAdOx1 and MVA based vaccine candidates against MERS-CoV elicit neutralising antibodies and cellular immune responses in mice

The Middle East respiratory syndrome coronavirus (MERS-CoV) has infected more than 1900 humans, since 2012. The syndrome ranges from asymptomatic and mild cases to severe pneumonia and death. The virus is believed to be circulating in dromedary camels without notable symptoms since the 1980s. Therefore, dromedary camels are considered the only animal source of infection. Neither antiviral drugs nor vaccines are approved for veterinary or medical use despite active research on this area. Here, we developed four vaccine candidates against MERS-CoV based on ChAdOx1 and MVA viral vectors, two candidates per vector. All vaccines contained the full-length spike gene of MERS-CoV; ChAdOx1 MERS vaccines were produced with or without the leader sequence of the human tissue plasminogen activator gene (tPA) where MVA MERS vaccines were produced with tPA, but either the mH5 or F11 promoter driving expression of the spike gene. All vaccine candidates were evaluated in a mouse model in prime only or prime-boost regimens. ChAdOx1 MERS with tPA induced higher neutralising antibodies than ChAdOx1 MERS without tPA. A single dose of ChAdOx1 MERS with tPA elicited cellular immune responses as well as neutralising antibodies that were boosted to a significantly higher level by MVA MERS. The humoral immunogenicity of a single dose of ChAdOx1 MERS with tPA was equivalent to two doses of MVA MERS (also with tPA). MVA MERS with mH5 or F11 promoter induced similar antibody levels; however, F11 promoter enhanced the cellular immunogenicity of MVA MERS to significantly higher magnitudes. In conclusion, our study showed that MERS-CoV vaccine candidates could be optimized by utilising different viral vectors, various genetic designs of the vectors, or different regimens to increase immunogenicity. ChAdOx1 and MVA vectored vaccines have been safely evaluated in camels and humans and these MERS vaccine candidates should now be tested in camels and in clinical trials.

Combined HDAC and BET inhibition to enhance cancer vaccine-elicited T-cell responses.

e14632 Background: The combined inhibition of histone deacetylases (HDAC) and the proteins of the bromo and extra terminal (BET) family have recently shown therapeutic efficacy against pancreatic ductal adenocarcinoma, melanoma and lymphoma cancers in murine studies. However, in these studies the role of the immune system in therapeutically controlling these cancers was not explored. Methods: We sought to investigate the effect of the HDAC inhibitor romidepsin (RMD) and the BET inhibitor I-BET151, both singly and in combination, on vaccine elicited immune responses. C57Bl/6 mice were immunized with differing vaccines (Adenoviral, protein) in prime-boost regimens, under treatment with RMD, I-BET151, or RMD+I-BET151. Results: The combination RMD+I-BET151, administered during Adenoviral prime-boost vaccination, resulted in the significant increase in the frequency and number of antigen-specific CD8 T cells. RMD+I-BET151 treatment affected vaccine-elicited secondary T cell responses, significantly increasing the frequency of IFN-γ+ splenic CD8 T cells and maintaining their dual IFN-γ+TNFa+ polyfunctionality. These CD8 T cells maintained their protective ability against Listeria monocytogenes, and protected against B16-OVA challenge. The significant augmentation of vaccine elicited CD8 T cell responses under RMD+I-BET151 treatment was additionally observed following protein (OVA+CpG) prime-boost vaccination, resulting in greater protection against B16-OVA challenge and enhanced survival. T-regulatory cell (FoxP3+CD4+) frequency and total CD4 and CD8 cell numbers remained unaltered following RMD+I-BET151 treatment. Conclusions: Combined HDAC and BET inhibition resulted in greater vaccine-elicited CD8 T cell responses following immunization by multiple vaccine platforms, and enhanced protection against B16-OVA challenges. We are currently assessing immunological mechanisms of action for this combined HDAC and BET inhibition.

The Magnaporthe oryzae nitrooxidative stress response suppresses rice innate immunity during blast disease.

Understanding how microorganisms manipulate plant innate immunity and colonize host cells is a major goal of plant pathology. Here, we report that the fungal nitrooxidative stress response suppresses host defences to facilitate the growth and development of the important rice pathogen Magnaporthe oryzae in leaf cells. Nitronate monooxygenases encoded by NMO genes catalyse the oxidative denitrification of nitroalkanes. We show that the M. oryzae NMO2 gene is required for mitigating damaging lipid nitration under nitrooxidative stress conditions and, consequently, for using nitrate and nitrite as nitrogen sources. On plants, the Δnmo2 mutant strain penetrated host cuticles like wild type, but invasive hyphal growth in rice cells was restricted and elicited plant immune responses that included the formation of cellular deposits and a host reactive oxygen species burst. Development of the M. oryzae effector-secreting biotrophic interfacial complex (BIC) was misregulated in the Δnmo2 mutant. Inhibiting or quenching host reactive oxygen species suppressed rice innate immune responses and allowed the Δnmo2 mutant to grow and develop normally in infected cells. NMO2 is thus essential for mitigating nitrooxidative cellular damage and, in rice cells, maintaining redox balance to avoid triggering plant defences that impact M. oryzae growth and BIC development.

Immunization with Tc52 or its amino terminal domain adjuvanted with c-di-AMP induces Th17+Th1 specific immune responses and confers protection against Trypanosoma cruzi.

The development of new adjuvants enables fine modulation of the elicited immune responses. Ideally, the use of one or more adjuvants should result in the induction of a protective immune response against the specific pathogen. We have evaluated the immune response and protection against Trypanosoma cruzi infection in mice vaccinated with recombinant Tc52 or its N- and C-terminal domains (NTc52 and CTc52) adjuvanted either with the STING (Stimulator of Interferon Genes) agonist cyclic di-AMP (c-di-AMP), a pegylated derivative of α-galactosylceramide (αGC-PEG), or oligodeoxynucleotides containing unmethylated CpG motifs (ODN-CpG). All groups immunized with the recombinant proteins plus adjuvant: Tc52+c-di-AMP, NTc52+c-di-AMP, CTc52+c-di-AMP, NTc52+c-di-AMP+αGC-PEG, NTc52+CpG, developed significantly higher anti-Tc52 IgG titers than controls. Groups immunized with c-di-AMP and Tc52, NTc52 or CTc52 showed the highest Tc52-specific IgA titers in nasal lavages. All groups immunized with the recombinant proteins plus adjuvant developed a strong specific cellular immune response in splenocytes and lymph node cells with significant differences for groups immunized with c-di-AMP and Tc52, NTc52 or CTc52. These groups also showed high levels of Tc52-specific IL-17 and IFN-γ producing cells, while NTc52+CpG group only showed significant difference with control in IFN-γ producing cells. Groups immunized with c-di-AMP and Tc52, NTc52 or CTc52 developed predominantly a Th17 and Th1immune response, whereas for NTc52+CpG it was a dominant Th1 response. It was previously described that αGC-PEG inhibits Th17 differentiation by activating NKT cells. Thus, in this work we have also included a group immunized with both adjuvants (NTc52+c-di-AMP+αGC-PEG) with the aim to modulate the Th17 response induced by c-di-AMP. This group showed a significant reduction in the number of Tc52-specific IL-17 producing splenocytes, as compared to the group NTc52+c-di-AMP, which has in turn correlated with a reduction in protection against infection. These results suggest that the Th17 immune response developed after immunizing with NTc52+c-di-AMP could have a protective role against T. cruzi infection. Groups NTc52+c-di-AMP, Tc52+c-di-AMP and NTc52PB, were the ones that showed better protection against infection with lower parasitemia and weight loss, and higher survival.

A Novel DNA Vaccine Platform Enhances Neo-antigen-like T Cell Responses against WT1 to Break Tolerance and Induce Anti-tumor Immunity

Tumor-associated antigens have emerged as important immunotherapeutic targets in the fight against cancer. Germline tumor antigens, such as WT1, Wilms' tumor gene 1, are overexpressed in many human malignancies but have low expression in somatic tissues. Recent vaccination approaches to target WT1 have been hampered by poor invivo immune potency, likely due to the conserved self-antigen nature of WT1. In this study, we use a novel synthetic micro-consensus SynCon DNA vaccine approach with the goal of breaking tolerance and increasing vaccine immune potency. This approach induced new, neo-antigen-like responses that were superior to those induced by native WT1 DNA immunogens for driving Tcell immunity and breaking tolerance. Non-human primates (NHPs) vaccinated with SynCon WT1 antigens elicited immune responses against native rhesus WT1 peptides. When delivered by electroporation (EP) in mice, SynCon-based WT1 constructs elicited strong CD4 and CD8 Tcell responses (including IFN-γ, CD107a, and TNF-α) to both native and consensus peptides. In addition, SynCon WT1 vaccine-induced antibodies recognized native WT1 invitro. Vaccination with the SynCon WT1 immunogens was capable of slowing tumor growth in therapeutic models invivo. These data support thefurther study of synthetic consensus DNA vaccines for breaking tolerance to important germline antigens.

The effects of CpG-ODNs and Chitosan adjuvants on the elicitation of immune responses induced by the HIV-1-Tat-based candidate vaccines in mice.

HIV1-Tat-based vaccines could elicit broad, durable and neutralizing immune responses and are considered as potential AIDS vaccines. The present study aims to formulate CpG-ODNs adjuvant and Chitosan with Tat protein to enhance the immunogenicity of HIV-1-Tat-based candidate vaccines and to investigate their efficacies in mice. To this end, we added CpG-ODNs, Chitosan and Alum as adjuvants to the Tat-based candidate vaccine formulations. Then, we compared frequency and magnitude of both humoral and cellular immune responses from mice immunized with the adjuvant-formulated Tat candidate vaccines against those obtained from mice immunized with recombinant Tat protein alone. Mice were subcutaneously immunized three times at 2-week intervals with the candidate vaccines. Measurements of anti-Tat immune responses showed that all vaccinated groups had a good immunity compared to the control groups and developed high levels of both humoral and cellular responses. However, immunized mice with CpG-ODNs, and Chitosan-adjuvanted Tat vaccines elicited stronger T-cell responses (both humoral and cellular immunity) compared to the others. These data suggest that co-administration of recombinant Tat protein with CpG-ODNs and Chitosan may serve as a potential formulation for enhancing of the Tat vaccine-induced immunity and might have effects on shaping Th polarization induced by HIV1-Tat protein vaccines.

A novel design of a multi-antigenic, multistage and multi-epitope vaccine against Helicobacter pylori: An in silico approach

Helicobacter pylori have colonized the gastric mucosa of half of the population worldwide. This bacterium is classified as a definitive type I carcinogen by the World Health Organization and no effective vaccine has been found against it yet. Thus, a logical and rational vaccine design against H. pylori is necessary. Because of its tremendous complexity and elicited immune responses, the vaccine design should considered multiple antigens to enhance immune-protection, involved in the different stages of pathogenesis besides inducing a specific immune response by B- and T-cell multi-epitopes. In this study, emphasis was placed on the design of a new unique vaccine named CTB-multiHp. In silico techniques were used to design a chimeric construct consisting of cholera toxin B subunit fused to multi-epitope of urease B (residue 148–158, 188–198), cytotoxin-associated gene A (residue 584–602), neutrophil activating protein (residue 4–28), vacuolating cytotoxin gene A (residue 63–81), H. pylori adhesine A (residue77–99), heat shock protein A (residue 32–54) and gamma glutamyl transpeptidase (residue 271–293). The tertiary structure and features of the vaccine were analyzed. The chimeric protein was expressed in Escherichia coli BL21 and the serology analyses indicated that the CTB-multiHp protein produced exhibit immune-reactivity. The results showed that CTB-multiHp could be a good vaccine candidate against H. pylori. Ongoing studies will evaluate the effects of CTB-multiHp against H. pylori infection.

Long-term consequences of topical dexamethasone treatment during acute corneal HSV-1 infection on the immune system.

Herpes simplex virus type 1 (HSV-1) is a leading cause of neurotrophic keratitis (NTK). NTK is characterized by decreased corneal sensation from damage to the corneal sensory fibers. We have reported on the regression of corneal nerves and their function during acute HSV-1 infection. That nerve loss is followed by an aberrant process of nerve regeneration during the latent phase of infection that lacks functional recovery. We recently showed the elicited immune response in the infected cornea, and not viral replication itself, is part of the mechanism responsible for the nerve degeneration process after infection. Specifically, we showed infected corneas topically treated with dexamethasone (DEX) significantly retained both structure and sensitivity of the corneal nerve network in comparison to mice treated with control eye drops, consistent with decreased levels of proinflammatory cytokines and reduced influx of macrophages and CD8+ T cells into the cornea. This study was undertaken to analyze the long-term effect of such a localized, immunosuppressive paradigm (DEX drops on the cornea surface during the first 8 d of HSV-1 infection) on the immune system and on corneal pathology. We found the profound immunosuppressive effect of DEX on lymphoid tissue was sustained in surviving mice for up to 30 d postinfection (p.i.). DEX treatment had prolonged effects, preserving corneal innervation and its function and blunting neovascularization, as analyzed at 30 d p.i. Our data support previously reported observations of an association between the persistent presence of inflammatory components in the latently infected cornea and structural and functional nerve defects in NTK.

Isolation and partial characterization of an immunogenic antigen of Giardia lamblia

Humoral and cellular immune responses play an important role during Giardia lamblia infection. Several Giardia proteins have been identified as immunogenic antigens based on their elicited humoral immune response. Poorly is known about Giardia antigens that stimulate a cellular immune response. The main purpose of this study was to isolate and partial characterize an immunogenic antigen (5G8) of G. lamblia. The 5G8 protein was isolated from G. lamblia trophozoite lysates by affinity chromatography using moAb 5G8-coupled CNBr-Sepharose. The isolated protein was analysed by electrospray tandem mass spectrometry (ESI-MS/MS), and by diverse bioinformatics tools (GiardiaDB, BLASTn, BLASTp and ExPASy). Additionally, several biochemical and immunological characteristics of the isolated protein were analysed. By ESI-MS/MS the amino acidic 5G8 sequence was deduced. The 5G8 antigen belongs to the VSP family proteins of G. lamblia. This protein is composed by one polypeptide chain (±71kDa). Using the algorithm SYFPHEITI, we identified candidate CD4+ T-cell epitopes from the 5G8 antigen, which can elicit cell-mediated immune responses. In this study, we have identified a G. lamblia protein that induces a strong immune response in infected mice. The biochemical and immunological characterization of the immunogenic 5G8 antigen may contribute to the rational design of a Giardia vaccine.

Current advances in renewal mechanisms of intestinal epithelial cells along the crypt-villus axis

The small intestine is not only an organ for food digestion and nutrient absorption but also an integral part of the immune and endocrine systems. Differentiation of enterocytes plays an important role in the damage repair mechanism after immune response elicitation by the intestine, for restoring the intestinal barrier function and homeostasis. Recently, research related to self-renewal, differentiation, and regulation of the intestinal epithelial crypt stem cells has been developing rapidly. In this review, we attempt to sum up recent studies related to the expression pattern of genes and proteins along the crypt-villus axis, and the effect of signaling pathways, transcription factors, and epigenetic modifications on the differentiation of crypt stem cells. We also examine the mechanisms by which nutritional factors influence the differentiation and damage repair processes of the intestinal epithelial cells. This review could provide valuable theoretical framework in nutritional and pharmacological aspects and guidance for intervention and treatment of intestinal damage and related diseases.

Advances in Immunotherapy for Melanoma: A Comprehensive Review

Melanomas are tumors originating from melanocytes and tend to show early metastasis secondary to the loss of cellular adhesion in the primary tumor, resulting in high mortality rates. Cancer-specific active immunotherapy is an experimental form of treatment that stimulates the immune system to recognize antigens on the surface of cancer cells. Current experimental approaches in immunotherapy include vaccines, biochemotherapy, and the transfer of adoptive T cells and dendritic cells. Several types of vaccines, including peptide, viral, and dendritic cell vaccines, are currently under investigation for the treatment of melanoma. These treatments have the same goal as drugs that are already used to stimulate the proliferation of T lymphocytes in order to destroy tumor cells; however, immunotherapies aim to selectively attack the tumor cells of each patient. In this comprehensive review, we describe recent advancements in the development of immunotherapies for melanoma, with a specific focus on the identification of neoantigens for the prediction of their elicited immune responses. This review is expected to provide important insights into the future of immunotherapy for melanoma.

Immunogenicity and protective efficacy induced by self-amplifying mRNA vaccines encoding bacterial antigens

Nucleic acid vaccines represent an attractive approach to vaccination, combining the positive attributes of both viral vectors and live-attenuated vaccines, without the inherent limitations of each technology. We have developed a novel technology, the Self-Amplifying mRNA (SAM) platform, which is based on the synthesis of self-amplifying mRNA formulated and delivered as a vaccine. SAM vaccines have been shown to stimulate robust innate and adaptive immune responses in small animals and non-human primates against a variety of viral antigens, thus representing a safe and versatile tool against viral infections. To assess whether the SAM technology could be used for a broader range of targets, we investigated the immunogenicity and efficacy of SAM vaccines expressing antigens from Group A (GAS) and Group B (GBS) Streptococci, as models of bacterial pathogens. Two prototype bacterial antigens (the double-mutated GAS Streptolysin-O (SLOdm) and the GBS pilus 2a backbone protein (BP-2a)) were successfully expressed by SAM vectors. Mice immunized with both vaccines produced significant amounts of fully functional serum antibodies. The antibody responses generated by SAM vaccines were capable of conferring consistent protection in murine models of GAS and GBS infections. Inclusion of a eukaryotic secretion signal or boosting with the recombinant protein resulted in higher specific-antibody levels and protection. Our results support the concept of using SAM vaccines as potential solution for a wide range of both viral and bacterial pathogens, due to the versatility of the manufacturing processes and the broad spectrum of elicited protective immune response.

Co-Administration of Lipid Nanoparticles and Sub-Unit Vaccine Antigens Is Required for Increase in Antigen-Specific Immune Responses in Mice.

A vast body of evidence suggests that nanoparticles function as potent immune-modulatory agents. We have previously shown that Merck proprietary Lipid NanoParticles (LNPs) markedly boost B-cell and T-cell responses to sub-unit vaccine antigens in mice. To further evaluate the specifics of vaccine delivery and dosing regimens in vivo, we performed immunogenicity studies in BALB/c and C57BL/6 mice using two model antigens, Hepatitis B Surface Antigen (HBsAg) and Ovalbumin (OVA), respectively. To assess the requirement for co-administration of antigen and LNP for the elicitation of immune responses, we evaluated immune responses after administering antigen and LNP to separate limbs, or administering antigen and LNP to the same limb but separated by 24 h. We also evaluated formulations combining antigen, LNP, and aluminum-based adjuvant amorphous aluminum hydroxylphosphate sulfate (MAA) to look for synergistic adjuvant effects. Analyses of antigen-specific B-cell and T-cell responses from immunized mice revealed that the LNPs and antigens must be co-administered—both at the same time and in the same location—in order to boost antigen-specific immune responses. Mixing of antigen with MAA prior to formulation with LNP did not impact the generation of antigen-specific B-cell responses, but drastically reduced the ability of LNPs to boost antigen-specific T-cell responses. Overall, our data demonstrate that the administration of LNPs and vaccine antigen together enables their immune-stimulatory properties.

Evaluation of variability in antibody response induced by vaccination against Peste des petits ruminants (PPR) in Malpura and Avikalin sheep

Amongst several trans-boundary diseases of small ruminants in India, Peste des petits ruminants (PPR) is a devastating disease due to its spread and economic importance. The main strategy for prevention of this disease is the vaccination with attenuated whole virus vaccine. Present study was carried out to identify the sources of variation and also to unravel the genetic variance in the PPR virus (PPR) vaccine elicited immune response in 231 Avikalin and 398 Malpura sheep lambs maintained at organized institute flocks in the semi-arid region of India. Average age at vaccination was 108.5 days. Sera were tested by competitive ELISA (C-ELISA), an attenuated PPR (Sungri) was used as the coating antigen. Results revealed significant variability for response to vaccination. Per cent inhibition (PI) values at 0day of vaccination (0DPrV) was 33.9% and 29.8% in Avikalin and Malpura lambs, respectively. At 28days post vaccination (28DPV) PI was 62.7% in Avikalin and 58.7% in Malpura lambs. On 28DPV, the protective titre (PI>50%) was shown by 82.4% Avikalin lambs and 76.2% Malpura lambs. Among environmental determinants, breed, cohort, season and age at vaccination proved to be significant sources of variation (P<0.05). Factors determining the better odds of protection need to be exploited properly to assure protection. The estimate of heritability (h2±SE) at 28DPV was 0.02±0.12 in Malpura sheep, however it was 0.54±0.28 in Avikalin sheep.