Enhanced Antibody Responses Research Articles

Immunization with HIV-1 envelope T20-encoding DNA vaccines elicits cross-clade neutralizing antibody responses

ABSTRACTBackground: Genetic immunization is expected to induce the expression of antigens in a native form. The encoded peptide epitopes are presented on endogenous MHC molecules, mimicking antigen presentation during a viral infection. We have explored the potential of enfuvirtide (T20), a short HIV peptide with antiviral properties, to enhance immune response to HIV antigens. To generate an expression vector, the T20 sequence was cloned into a conventional plasmid, the novel minicircle construct, and a replicon plasmid. In addition, 3 conventional plasmids that express the envelope of HIV-1 subtypes A, B and C and contain T20 in their gp41 sequences were also tested. Results: All combinations induced HIV-specific antibodies and cellular responses. The addition of T20 as a peptide and as an expression cassette in the 3 DNA vectors enhanced antibody responses. The highest anti-HIV-1 Env titers were obtained by the replicon T20 construct. This demonstrates that besides its known antiviral activity, T20 promotes immune responses. We also confirm that the combination of slightly divergent antigens improves immune responses. Conclusions: The antiretroviral T20 HIV-1 sequence can be used as an immunogen to elicit binding and neutralizing antibodies against HIV-1. These, or similarly modified gp41 genes/peptides, can be used as priming or boosting components for induction of broadly neutralizing anti-HIV antibodies. Future comparative studies will reveal the optimal mode of T20 administration.

Replicon Particle Expressing the E2 Glycoprotein of Bovine Viral Diarrhea Virus Immunization and Evaluation of Antibody Response.

The objective of this study was to develop a new antigen delivery system using an alphavirus replicon particle (RP) to induce humoral antibody responses against bovine viral diarrhea virus (BVDV) recombinant antigen produced from envelope glycoprotein E2. An alphavirus RP expressing the E2 glycoprotein of BVDV was used for immunization of pigs. A fluorescent microsphere immunoassay (FMIA) has been applied to detect BVDV E2 antigen-specific antibody isotype in pig immunized with alphavirus RP. Full-length BVDV E2 (aa 1-375) was cleaved into several pieces, eight E2 DNA fragments, including full-length DNA, were cloned into expression vector pHUE, and the recombinant proteins expressed in BL-21 (DE3) Escherichia coli. After successful conjugation of purified proteins with microsphere beads, a multiplex FMIA platform was constructed, and BVDV E2 alphavirus-based RP-immunized animal serum samples were tested in the presence of bead-bound antigen targets. The results were represented as mean fluorescence intensity (MFI); the MFI values were converted to sample value/positive value (S/P) ratios. BVDV E2 (aa 1-183) showed the highest MFI values of eight recombinant E2 fragments when the specific activity of each fragment was tested. In immunized animals, data for BVDV E2-specific IgA, IgG, and IgM in serum and only IgG and IgA in oral fluids were recorded. The MFI values for the positive serum sample showed a 100-fold increase compared with the negative serum sample. Antibody isotype to BVDV E2 antigens showed that IgG > IgM > IgA in serum, whereas IgG > IgA > IgM in oral fluids. The data presented in this study suggested that boosting with the same doses of alphavirus RP in 3-week intervals may potentially enhance antibody response. The experimental results demonstrate that alphavirus RP-expressing BVDV E2 antigen induces antibody response in pig.

Identification of Protective B-Cell Epitopes within the Novel Malaria Vaccine Candidate Plasmodium falciparum Schizont Egress Antigen 1.

Naturally acquired antibodies to Plasmodium falciparum schizont egress antigen 1 (PfSEA-1A) are associated with protection against severe malaria in children. Vaccination of mice with SEA-1A from Plasmodium berghei (PbSEA-1A) decreases parasitemia and prolongs survival following P. berghei ANKA challenge. To enhance the immunogenicity of PfSEA-1A, we identified five linear B-cell epitopes using peptide microarrays probed with antisera from nonhuman primates vaccinated with recombinant PfSEA-1A (rPfSEA-1A). We evaluated the relationship between epitope-specific antibody levels and protection from parasitemia in a longitudinal treatment-reinfection cohort in western Kenya. Antibodies to three epitopes were associated with 16 to 17% decreased parasitemia over an 18-week high transmission season. We are currently designing immunogens to enhance antibody responses to these three epitopes.

BAMBI is a negative regulator of humoral immune responses.

Abstract BAMBI (Bone Morphogenetic Protein and Activin Membrane Bound Inhibitor) is a plasma membrane-associated negative regulator of TGFβ signaling. Using mice deficient in BAMBI and anti-BAMBI monoclonal antibodies, we have recently demonstrated the contribution of this TGFβ inhibitor to the regulation of CD4 T-cell differentiation into pathogenic TH17 cells and tolerogenic regulatory T cells. In the present study, we explored the possible involvement of BAMBI in the control of humoral immune responses. We demonstrated that BAMBI-KO mice developed increased antibody responses against T-independent antigens. In addition, these mutant mice also exhibited enhanced antibody responses against several T-dependent antigens administered by different routes and even in the absence of adjuvants. Using adoptive CD4 T-cell transfer experiments and double WT/BAMBI-KO bone marrow chimeric mice we showed that in the mutant mice, B cells exhibited intrinsic defects that improved their interaction with antigen-specific activated CD4 T cells and their subsequent activation and differentiation into germinal center B cells and antibody secreting cells. In fact, B cells from BAMBI-KO mice exhibited enhanced proliferative responses in vitro and expressed higher levels of surface molecules involved in CD4:B cell interactions. Finally, we demonstrated here that the enhanced T-dependent antibody responses observed in BAMBI-KO mice were reverted after long-term treatment with an anti-TGFβ monoclonal antibody. In conclusion, our present study described for the first time a negative role of BAMBI in the control of T-independent and Tdependent antibody responses through the regulation of TGFβ signaling.

Acute Exercise Alters Cell Populations Within Lymph Nodes Draining Exercising Muscle

Previous studies have reported an enhanced antibody response following vaccination coupled with acute exercise. Researchers have speculated that this immunomodulation may be due to the release of damage-associated molecular patterns in response to exercise and the concomitant migration of dendritic cells to lymph nodes. Because the majority of work in this area has been done in humans, rendering the invasive techniques required unrealistic, no study has yet examined the cell populations within the lymph nodes following acute exercise. PURPOSE: To determine if acute exercise changes the dendritic cell population within lymph nodes draining the exercising muscle. METHODS: Female BALB/c mice received an intramuscular injection of physiological saline in right and left quadriceps, and then performed either 90 minutes of moderate intensity treadmill running (EX) or remained near the treadmill without running (NO EX). Twenty-four hours following the injections, mice were euthanized (n = 7 per treatment group) and inguinal lymph nodes were collected. Cell populations within the inguinal lymph nodes were processed by flow cytometry using the antibodies allophycocyanin-Cy7-conjugated anti-mouse CD11c and Alexa Flour 700-conjugated anti-mouse MHC Class II (MHCII). Results were analyzed using FlowJo. RESULTS: Exercise did not significantly alter total cell number within the lymph nodes (EX: 5.86x106 ± 8.37x105 vs. NO EX: 4.82x106 ± 8.44x105, p = 0.40). However, EX mice had both a higher percentage (16.83 ± 4.69% vs. 5.25 ± 1.53%, p = 0.03) and absolute number (8.54x105 ± 1.53x105 vs. 2.73x105 ± 7.24x104, p = 0.00) of CD11c+ MHCII+ cells present in the inguinal lymph nodes as compared to NO EX mice. Exercise had no effect on the expression of the costimulatory molecules CD80 and CD86 as assessed by mean fluorescence intensity within the CD11c+ MHCII+ cell populations. CONCLUSIONS: Acute exercise alters the cell populations within the lymph nodes draining exercising muscles 24 hours post-injection, although an increase in costimulatory molecule expression is not evident at this time point. Whether these effects are more pronounced at earlier or later time points and the direct results on antibody production following exercise coupled with a vaccine remain to be elucidated.

Neutralizing and enhancing antibody responses to five genotypes of dengue virus type 1 (DENV-1) in DENV-1 patients.

Dengue virus (DENV) has four distinct serotypes, DENV-1-4, with four to six genotypes in each serotype. The World Health Organization recommends tetravalent formulations including one genotype of each serotype as safe and effective dengue vaccines. Here, we investigated the impact of genotype on the neutralizing antibody responses to DENV-1 in humans. Convalescent sera collected from patients with primary infection of DENV-1 were examined for neutralizing antibody against single-round infectious particles of the five DENV-1 genotypes (GI-GV). In both GI- and GIV-infected patients, their neutralizing antibody titres against the five genotypes were similar, differing ≤4-fold from the homogenotypic responses. The enhancing activities against the five genotypes were also similar in these sera. Thus, the genotype strains of DENV-1 showed no significant antigenic differences in these patients, suggesting that GI- or GIV-derived vaccine antigens should induce equivalent levels of neutralizing antibodies against all DENV-1 genotypes.

Immunogenicity and Protective Efficacy of the DAR-901 Booster Vaccine in a Murine Model of Tuberculosis.

BackgroundThe development of a novel tuberculosis vaccine is a leading global health priority. SRL172, an inactivated, whole-cell mycobacterial vaccine, was safe, immunogenic and reduced the incidence of culture-confirmed tuberculosis in a phase III trial in HIV-infected and BCG immunized adults in Tanzania. Here we describe the immunogenicity and protective efficacy of DAR-901, a booster vaccine against tuberculosis manufactured from the same seed strain using a new scalable method.MethodsWe evaluated IFN-γ responses by ELISpot and antibody responses by enzyme linked immunosorbent assay in C57BL/6 and BALB/c mice after three doses of DAR-901. In an aerosol challenge model, we evaluated the protective efficacy of the DAR-901 booster in C57BL/6 mice primed with BCG and boosted with two doses of DAR-901 at 4 dosage levels in comparison with homologous BCG boost.ResultsDAR-901 vaccination elicited IFN-γ responses to mycobacterial antigen preparations derived from both DAR-901 and Mycobacterium tuberculosis. DAR-901 immunization enhanced antibody responses to DAR-901 but not Mycobacterium tuberculosis lysate or purified protein derivative. Among animals primed with BCG, boosting with DAR-901 at 1 mg provided greater protection against aerosol challenge than a homologous BCG boost (lungs P = 0.036, spleen P = 0.028).ConclusionsDAR-901 induces cellular and humoral immunity and boosts protection from M. tuberculosis compared to a homologous BCG boost.

Adrenergic control of the adaptive immune response by diurnal lymphocyte recirculation through lymph nodes.

Various aspects of the immune system display circadian rhythms. Although lymphocyte trafficking has been suggested to show diurnal variations, the mechanisms and influences on immune responses are unclear. Here, we show in mice that inputs from adrenergic nerves contribute to the diurnal variation of lymphocyte recirculation through lymph nodes (LNs), which is reflected in the magnitude of the adaptive immune response. Neural inputs to β2-adrenergic receptors (β2ARs) expressed on lymphocytes reduced the frequency of lymphocyte egress from LNs at night, which was accompanied by an increase of lymphocyte numbers in LNs. Immunization during the period of lymphocyte accumulation in LNs enhanced antibody responses. The diurnal variation of the humoral immune response was dependent on β2AR-mediated neural signals and was diminished when lymphocyte recirculation through LNs was stopped. This study reveals the physiological role of adrenergic control of lymphocyte trafficking in adaptive immunity and establishes a novel mechanism that generates diurnal rhythmicity in the immune system.

Sustained antigen availability during germinal center initiation enhances antibody responses to vaccination

Natural infections expose the immune system to escalating antigen and inflammation over days to weeks, whereas nonlive vaccines are single bolus events. We explored whether the immune system responds optimally to antigen kinetics most similar to replicating infections, rather than a bolus dose. Using HIV antigens, we found that administering a given total dose of antigen and adjuvant over 1-2 wk through repeated injections or osmotic pumps enhanced humoral responses, with exponentially increasing (exp-inc) dosing profiles eliciting >10-fold increases in antibody production relative to bolus vaccination post prime. Computational modeling of the germinal center response suggested that antigen availability as higher-affinity antibodies evolve enhances antigen capture in lymph nodes. Consistent with these predictions, we found that exp-inc dosing led to prolonged antigen retention in lymph nodes and increased Tfh cell and germinal center B-cell numbers. Thus, regulating the antigen and adjuvant kinetics may enable increased vaccine potency.

Genome-wide association studies of immune, disease and production traits in indigenous chicken ecotypes.

BackgroundThe majority of chickens in sub-Saharan Africa are indigenous ecotypes, well adapted to the local environment and raised in scavenging production systems. Although they are generally resilient to disease challenge, routine vaccination and biosecurity measures are rarely applied and infectious diseases remain a major cause of mortality and reduced productivity. Management and genetic improvement programmes are hampered by lack of routine data recording. Selective breeding based on genomic technologies may provide the means to enhance sustainability. In this study, we investigated the genetic architecture of antibody response to four major infectious diseases [infectious bursal disease (IBDV), Marek’s disease (MDV), fowl typhoid (SG), fowl cholera (PM)] and resistance to Eimeria and cestode parasitism, along with two production traits [body weight and body condition score (BCS)] in two distinct indigenous Ethiopian chicken ecotypes. We conducted variance component analyses, genome-wide association studies, and pathway and selective sweep analyses.ResultsThe large majority of birds was found to have antibody titres for all pathogens and were infected with both parasites, suggesting almost universal exposure. We derived significant moderate to high heritabilities for IBDV, MDV and PM antibody titres, cestodes infestation, body weight and BCS. We identified single nucleotide polymorphisms (SNPs) with genome-wide significance for each trait. Based on these associations, we identified for each trait, pathways, networks and functional gene clusters that include plausible candidate genes. Selective sweep analyses revealed a locus on chromosome 18 associated with viral antibody titres and resistance to Eimeria parasitism that is within a positive selection signal. We found no significant genetic correlations between production, immune and disease traits, implying that selection for altered antibody response and/or disease resistance will not affect production.ConclusionsWe confirmed the presence of genetic variability and identified SNPs significantly associated with immune, disease and production traits in indigenous village chickens. Results underpin the feasibility of concomitant genetic improvement for enhanced antibody response, resistance to parasitism and productivity within and across indigenous chicken ecotypes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12711-016-0252-7) contains supplementary material, which is available to authorized users.

Abstract # 1706 Morning vaccination enhances antibody response over afternoon vaccination: A cluster-randomised trial of older adults

Background Older adults have reduced antibody responses to vaccination due to immune ageing. Behavioural interventions have been tested, mainly in younger adults, including psychological stress and exercise, with mixed success in improving antibody responses. Given the diurnal variations in various immune system components, this study examined whether a behavioural intervention – altering the time of day of vaccination – might improve vaccination responses. Methods 24 General Practices from the UK were cluster-randomised to morning (9–11 am) or afternoon (3–5 pm) vaccination times for the annual influenza vaccination programme. 276 adults aged 65+ years (without a current infection or immune disorder or taking immunosuppressant medication) were vaccinated; blood samples were taken pre-vaccination and one month later. The primary outcome was the increase in antibody titres to the three vaccine influenza strains at one month post-vaccination. Serum cytokines and steroid hormone concentrations were analysed at baseline as potential mechanisms of effect. Results Morning vaccination yielded higher antibody levels for the H1N1 A-strain, p = .02, and B-strain, p = .01, but not H3N2 A-strain, p = .35. Cytokines and steroid hormones were not related to antibody responses, although a subsequent study revealed higher naive T cell frequency in the morning ( p = .001). Conclusions This simple manipulation in the timing of vaccination may be beneficial for the influenza antibody response in older adults, and potentially other vaccines.

Altering the time of vaccination against respiratory pathogens to enhance antibody response and performance of feeder cattle.

Ninety Angus × Hereford calves were ranked by sex, BW, and age and assigned to 1 of 3 vaccination schemes against the bovine respiratory disease complex: 1) vaccination at weaning (d 0) and a booster at feedlot entry (d 30; CON; = 30), 2) vaccination 15 d before weaning (d -15) and a booster 15 d before feedlot entry (d 15; EARLY; = 30), and 3) vaccination 15 d after weaning (d 15) and a booster 15 d after feedlot entry (d 45; DELAYED; = 30). From d -15 to 7, calves were maintained as a single group on pasture. On d 8, calves were placed into 1 of 18 drylot pens (6 pens/treatment; 5 calves/pen) and fed alfalfa-triticale hay. On d 29, calves were transported 1,440 km in a livestock trailer and unloaded on d 30 at the same feed yard with the same pen arrangement used prior to transport. From d 30 to 75, calves were fed a receiving diet based on alfalfa-triticale hay + corn-based concentrate. Calf BW was recorded on 2 consecutive days (d -15, -14, 0, 1, 28, 29, 75, and 76). Blood samples were collected on d -15, 0, 15, 30, 45, 60, and 75. The EARLY calves had less ( ≤ 0.09) ADG before weaning (d -15 to -1); however, they had greater ( ≤ 0.01) ADG during feedlot receiving (d 30 to 75) compared with calves with the other treatments. During preconditioning (d 0 to 29), CON calves had greater ( ≤ 0.04) DMI compared with EARLY and DELAYED calves. During feedlot receiving, no treatment differences were detected ( ≥ 0.17) for hay or concentrate DMI, G:F, and morbidity and mortality rates. There were no treatment effects on calf BW at weaning and at the end of the preconditioning or receiving periods ( ≥ 0.65). Plasma concentrations of antibodies against were greater ( ≤ 0.05) in EARLY calves than in CON and DELAYED calves on d 0, greater ( ≤ 0.04) for CON calves than for EARLY and DELAYED calves on d 15, greater ( ≤ 0.02) in DELAYED and EARLY calves than in CON calves on d 30, and greater ( = 0.03) in EARLY calves than in CON calves on d 75. Plasma concentrations of antibodies against bovine viral diarrhea viruses were greater ( ≤ 0.04) in EARLY calves than in CON and DELAYED calves on d 15 and greater for EARLY and CON calves than for DELAYED calves on d 30 and 45. Collectively, EARLY calves had greater plasma concentrations of antibodies against the evaluated pathogens at feedlot entry and increased ADG during receiving compared with their CON and DELAYED cohorts. Hence, anticipating initial and booster vaccinations against respiratory pathogens to provide both doses prior to feedlot entry appears to be a valid strategy to enhance cattle health and performance during feedlot receiving.

CCL17 combined with CCL19 as a nasal adjuvant enhances the immunogenicity of an anti-caries DNA vaccine in rodents.

CCL19 and its receptor CCR7 are essential molecules for facilitating the trafficking of mature dendritic cells (DCs) and helping to establish a microenvironment in lymphoid tissues to initiate primary immune responses, whereas CCL17 is required in the CCR7-CCL19-dependent migration of DCs. In this study we examined whether co-administration of CCL17 and CCL19 could enhance the immunogenicity of an anti-caries DNA vaccine, pCIA-P, in rodents. Plasmids encoding CCL17 (pCCL17/VAX) and CCL19 (pCCL19/VAX) were constructed. BALB/c mice were intranasally administered pCCL17/VAX, pCCL19/VAX, or pCCL17/VAX plus pCCL19/VAX, the migration of DCs to the spleen and draining lymph nodes (DLNs) was assessed with flow cytometry. The mice were co-administered pCIA-P; and the anti-PAc antibodies in the serum and saliva were detected with ELISA. Wistar rats were orally challenged with Streptococcus mutans and then administered pCIA-P in combination with pCCL17/VAX, pCCL19/VAX, or pCCL17/VAX plus pCCL19/VAX. The amount of S mutans sustained on rat molar surfaces was assessed using a colony forming assay. Caries activity was scored with the Keyes method. Co-administration of the CCL17 and CCL19 genes in mice caused a greater increase in the number of mature DCs in the spleen and DLNs compared with administration of CCL17 or CCL19 genes alone. CCL17 and CCL19 double-adjuvant plus pCIA-P induced significantly higher levels of anti-PAc salivary IgA and anti-PAc serum IgG antibody in mice, and strengthened the ability of pCIA-P in inhibiting the colonization of S mutans on rat tooth surfaces. The caries activity of the combined adjuvant group was significantly lower than that of the pCCL17/VAX or the pCCL19/VAX group. A nasal adjuvant consisting of a combination of CCL17 and CCL19 attracts more mature DCs to secondary lymphoid tissues, inducing enhanced antibody responses against the anti-caries DNA vaccine pCIA-P and reducing S mutans infection in rodents.

Morning vaccination enhances antibody response over afternoon vaccination: A cluster-randomised trial

ObjectivesOlder adults are less able to produce a protective antibody response to vaccinations. One factor that contributes to this is immune ageing. Here we examined whether diurnal variations in immune responses might extend to the antibody response to vaccination. DesignWe utilised a cluster-randomised trial design. Setting24 General Practices (GPs) across the West Midlands, UK who were assigned to morning (9–11am; 15 surgeries) or afternoon (3–5pm; 9 surgeries) vaccination times for the annual UK influenza vaccination programme. Participants276 adults (aged 65+ years and without a current infection or immune disorder or taking immunosuppressant medication). InterventionsParticipants were vaccinated in the morning or afternoon between 2011 and 2013. Main outcome measuresThe primary outcome was the change in antibody titres to the three vaccine influenza strains from pre-vaccination to one month post-vaccination. Secondary outcomes of serum cytokines and steroid hormone concentrations were analysed at baseline to identify relationships with antibody responses. ResultsThe increase in antibody levels due to vaccination differed between morning and afternoon administration; mean difference (95% CI) for H1N1 A-strain, 293.3 (30.97–555.66) p=.03, B-strain, 15.89 (3.42–28.36) p=.01, but not H3N2 A-strain, 47.0 (−52.43 to 146.46) p=.35; those vaccinated in the morning had a greater antibody response. Cytokines and steroid hormones were not related to antibody responses. No adverse events were reported. ConclusionsThis simple manipulation in the timing of vaccine administration to favour morning vaccination may be beneficial for the influenza antibody response in older adults, with potential implications for vaccination strategies generally. Trial registrationThis trial is registered with the ISRCTN (ISRCTN70898162).

Enhancement of antibody response by LAMP1 chimeric antigen in a DNA vaccine

Immunization by an antigen-encoding DNA (DNA vaccines) has shown promising results in rendering protection against some bacterial and viral diseases in fish. However, some studies showed that DNA vaccines induce variable levels of protection compared with the other types of vaccination. These results are driving the research interest against these infectious diseases to improve the efficacy of DNA vaccines. Recently, chimeric antigens in DNA vaccines have been reported to increase the protection against certain diseases by enhancing specific antibody responses. In this study, we assessed the use of a chimeric DNA vaccine by using lysosomeassociated membrane protein-1 (LAMP1) fused with the major capsule protein (MCP) from red seabream iridovirus. First, Japanese flounder (Paralichthys olivaceus) LAMP-1 (jfLAMP1) gene was cloned and characterized through tissue distribution and expression analysis. The ORF for jfLAMP1 gene has a length of 1248 bp that encodes for 415 aa (about 44 KDa) and shows highly conserved transmembrane and cytoplasmic domains as those of higher vertebrates. Then, jfLAMP1 was used as a carrier of MCP gene by replacing the intra-lysosomal domain, and subsequent inserting into an expression vector, pCI-neo. In the vaccination trial, juveniles of Japanese flounder were distributed into four groups: pCMCP (MCP in pCI-neo vector), pCLAMP1-MCP (chimeric DNA of jfLAMP1 and MCP in pCI-neo), rMCP (recombinant MCP) and pCI-neo (empty vector as a control). At 30 days post vaccination, blood samples were taken and the serum antibody titers were measured by ELISA. The 3 vaccinated groups showed higher antibody titers than pCI-neo group. The pCLAMP1-MCP vaccinated fish showed antibody levels significantly higher than pCMCP (p<0.05). These results will serve as a basis for the use of LAMP1-chimeric DNA vaccines to increase the immune response against certain infectious diseases, for which conventional DNA vaccines show marginal efficacy.

Enhancing immunogenicity and transmission-blocking activity of malaria vaccines by fusing Pfs25 to IMX313 multimerization technology.

Transmission-blocking vaccines (TBV) target the sexual-stages of the malaria parasite in the mosquito midgut and are widely considered to be an essential tool for malaria elimination. High-titer functional antibodies are required against target antigens to achieve effective transmission-blocking activity. We have fused Pfs25, the leading malaria TBV candidate antigen to IMX313, a molecular adjuvant and expressed it both in ChAd63 and MVA viral vectors and as a secreted protein-nanoparticle. Pfs25-IMX313 expressed from viral vectors or as a protein-nanoparticle is significantly more immunogenic and gives significantly better transmission-reducing activity than monomeric Pfs25. In addition, we demonstrate that the Pfs25-IMX313 protein-nanoparticle leads to a qualitatively improved antibody response in comparison to soluble Pfs25, as well as to significantly higher germinal centre (GC) responses. These results demonstrate that antigen multimerization using IMX313 is a very promising strategy to enhance antibody responses against Pfs25, and that Pfs25-IMX313 is a highly promising TBV candidate vaccine.

NIH Potency Test for Rv-Fc and Rv-K Based Candidate Anti-Rabies Vaccine Produced at Komipharm International Co., Ltd. Korea

Potency test for rabies vaccine is required to determine the vaccines potential to induce protective antibody response following vaccination. NIH potency test is the most widely used and internationally recommended potency assay for testing of inactivated rabies vaccines. Komipharm International Co., Ltd. Korea' has produced candidate anti-rabies vaccine from Rv-Fc strain expressing Fc region of Immunoglobulin G (IgG) originated from canine which enhance virus uptake by immune cells. This vaccine was tested for its potency according to NIH potency test protocol in the presence of Rv-K as a comparison, and 13.49 IU/ml and 3.16 IU/ml potency result obtained for Rv-Fc and Rv-K strain respectively. According to OIE recommendation for rabies vaccine, the potency should not be less than 1 IU/ml to be used for animal vaccination and both vaccines pass the requirement for animal vaccination. The modified rabies vaccine harboring canine Fc (Rv-Fc) has a high potency and can enhance antibody response after vaccination compared to PV strain based vaccine. Therefore, these vaccines can be used for animal vaccination at lower cost as it has more than recommended potency value.

A cytomegalovirus DNA vaccine induces antibodies that block viral entry into fibroblasts and epithelial cells

A vaccine to prevent congenital cytomegalovirus (CMV) infections is a national priority. Investigational vaccines have targeted the viral glycoprotein B (gB) as an inducer of neutralizing antibodies and phosphoprotein 65 (pp65) as an inducer of cytotoxic T cells. Antibodies to gB neutralize CMV entry into all cell types but their potency is low compared to antibodies that block epithelial cell entry through targeting the pentameric complex (gH/gL/UL128/UL130/UL131). Hence, more potent overall neutralizing responses may result from a vaccine that combines gB with pentameric complex-derived antigens. To assess the ability of pentameric complex subunits to generate epithelial entry neutralizing antibodies, DNA vaccines encoding UL128, UL130, and/or UL131 were formulated with Vaxfectin®, an adjuvant that enhances antibody responses to DNA vaccines. Mice were immunized with individual DNA vaccines or with pair-wise or trivalent combinations. Only the UL130 vaccine induced epithelial entry neutralizing antibodies and no synergy was observed from bi- or trivalent combinations. In rabbits the UL130 vaccine again induced epithelial entry neutralizing antibodies while UL128 or UL131 vaccines did not. To evaluate compatibility of the UL130 vaccine with DNA vaccines encoding gB or pp65, mono-, bi-, or trivalent combinations were evaluated. Fibroblast and epithelial entry neutralizing titers did not differ between rabbits immunized with gB alone vs. gB/UL130, gB/pp65, or gB/UL130/pp65 combinations, indicating a lack of antagonism from coadministration of DNA vaccines. Importantly, gB-induced epithelial entry neutralizing titers were substantially higher than activities induced by UL130, and both fibroblast and epithelial entry neutralizing titers induced by gB alone as well as gB/pp65 or gB/UL130/pp65 combinations were comparable to those observed in sera from humans with naturally-acquired CMV infections. These findings support further development of Vaxfectin®-formulated gB-expressing DNA vaccine for prevention of congenital CMV infections.

Abstract A54: Laser-assisted intradermal delivery of Xcl1-specific fusion vaccines induces potent antitumor response

Abstract Dendritic cells (DCs) are highly efficient specialized antigen-presenting cells and have been regarded as promising targets in cancer immunotherapy. Cross-presentation of antigen by a subset of DCs, the CD8α-type DCs to CD8+ T cells is a fundamentally important mechanism in the defense against pathogens and tumors. In human and mice, CD8α-type DCs that are able to cross present uniquely express the chemokine receptor Xcr1 that binds the Xcl1 chemokine. We targeted antigens to cross- presenting CD8α-type DCs using Xcl1 inserted in dimeric vaccine molecules. Bivalent Xcl1 fusion vaccines bind specifically to and chemoattract CD8α-type DCs in a Xcr1 dependent manner. With its easy accessibility and rich network of DCs, the skin appeals as a promising target site for vaccination. Using the PLEASE® laser microporation system, we specifically applied Xcl1 fusion vaccines into the murine dermis and targeted the cross-presenting CD8α-type dermal DCs. A single application of Xcl1 coupled to the modelantigen Ovalbumin (OVA) on the dermis of the mouse ear skin produced enhanced CD4 and CD8 T-cell responses, even in the absence of adjuvants. The first T-cell response was limited to the ear draining lymph node. This suggests that the application of antigens by laser microporation to the ear leads to a first localized immune response and thus limiting the possible amount of systemic side effects. However, such targeting of Xcl1-OVA also produced a striking enhancement of antibody responses. When the mice were challenged with B16 melanoma expressing OVA, treatment with the Xcl1-OVA could prevent development or mediate eradication of subcutaneous solid B16-OVA melanoma. We conclude that targeting of dimeric fusion vaccine molecules to dermal CD8α-type DCs by use of Xcl1 represents a novel and promising method for inducing cytotoxic T cell reponses. Targeting the right dendritic cell subset in the right cutaneous compartment via PLEASE® laser microporation is a promising approach for immunotherapy also e.g. against allergies and pathogens. Citation Format: Dorothea Terhorst, Dorothea Terhorst, Even Fossum, Bjarne Bogen, Sandrine Henri, Bernard Malissen. Laser-assisted intradermal delivery of Xcl1-specific fusion vaccines induces potent antitumor response. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr A54.

Epigenetic Regulation of Antibody Responses by the Histone H2A Deubiquitinase MYSM1.

B cell-mediated antibody response plays critical roles in protective immunity, as well as in the pathogenesis of allergic and autoimmune diseases. Epigenetic histone and DNA modifications regulate gene transcription and immunity; however, so far, little is known about the role of epigenetic regulation in antibody responses. In this study, we found that mice deficient in the histone H2A deubiquitinase MYSM1, despite their severe defect in B cell development, exhibit an enhanced antibody response against both T cell-dependent and independent antigens. We revealed that MYSM1 intrinsically represses plasma cell differentiation and antibody production. Mechanistic studies demonstrated that MYSM1 is a transcriptional activator of Pax5, the repressors of plasma cell differentiation, by facilitating key transcriptional factor recruitment and coordinating histone modifications at the Pax5 loci. Hence, this study uncovers a critical role for MYSM1 in epigenetically repressing plasma cell differentiation and antibody production, in addition to its opposing, active role in B cell development. Importantly, this study further provides a new target and strategy to modulate antibody production and responses with profound therapeutic implications.