Live attenuated Salmonella enterica serovar Choleraesuis vector delivering a virus-like particles induces a protective immune response against porcine circovirus type 2 in mice

The virus-like particles (VLPs) of porcine circovirus type 2 (PCV2) is an attractive vaccine candidate that retains the natural conformation of the virion but lacks the viral genome to replicate, thus balancing safety and immunogenicity. However, the assembly of VLPs requires cumbersome subsequent processes, hindering the development of related vaccines. In addition, as a subunit antigen, VLPs are defective in inducing cellular and mucosal immune responses. In this study, the capsid (Cap) protein of PCV2 was synthesized and self-assembled into VLPs in the recombinant attenuated S. Choleraesuis vector, rSC0016(pS-Cap). Furthermore, rSC0016(pS-Cap) induced a Cap-specific Th1-dominant immune response, mucosal immune responses, and neutralizing antibodies against PCV2. Finally, the virus genome copies in mice immunized with the rSC0016(pS-Cap) were significantly lower than those of the empty vector control group after challenge with PCV2. In conclusion, our study demonstrates the potential of using S. Choleraesuis vectors to delivery VLPs, providing new ideas for the development of PCV2 vaccines.     

A novel combined vaccine against classical swine fever and porcine epidemic diarrhea viruses elicits a significant Th2-favored humoral response in mice

Many Chinese breeding pigs are repeatedly vaccinated against classical swine fever virus (CSFV) and porcine epidemic diarrhea virus (PEDV), which cause fatal, highly contagious diseases. To reduce their high frequency vaccination-induced immune stress, we constructed a combined vaccine based on the E2 protein of CSFV and the S1 spike protein subunit of PEDV (named E2-S1). In mice, the E2-S1 vaccine elicited higher neutralizing antibody titers and IgG1/IgG2a ratios against CSFV and PEDV than those induced by individual E2 or S1 vaccines. Moreover, it elicited high IL-4 expression, but no IFN-γ expression. The results suggest that good compatibility exists between E2 and S1 antigens, and the E2-S1 vaccine can elicit a strong Th2-type cell-mediated humoral immune response. The E2-S1 recombinant fusion protein provides a novel vaccine candidate against both CSFV and PEDV, laying the foundation for future combination vaccines against swine diseases.     

Production and purification of an active CRM197 in Pichia pastoris and its immunological characterization using a Vi-typhoid antigen vaccine

CRM197 is a commonly used glycoconjugate carrier that improves the immunogenicity of vaccines, particularly in infants. Despite the advantages of this diphtheria toxoid mutant, low yields, production in inclusion bodies, and the requirement for specific growth conditions have limited the breadth of successful recombinant protein expression platforms available for its expression. We evaluated Pichia pastoris as a production host, using the methanol inducible AOX1 promoter and a modified α-mating factor signal peptide for secretion into the supernatant. Final purified yields >100 mg L⁻¹ culture were achieved when produced in a bioreactor, which is equivalent to the productivity obtained from bioprocesses using the native Corynebacterium diphtheriae host. Recombinant CRM197 was purified to ≥95% homogeneity and showed the expected endonuclease activity. Furthermore, mice immunized with a Salmonella enterica serovar Typhi capsular Vi antigen conjugated to our recombinant CRM197 showed greater than 5-fold increase in immune response. Overall, the results demonstrate that Pichia pastoris is a suitable expression host for the production of high quality CRM197 for vaccine applications.     

Evaluation of BioThrax® and AV7909 anthrax vaccines in adults 66 years of age or older

BackgroundMultiple Anthrax vaccines are licensed or in development for post-exposure prophylaxis in individuals 18 to 65 years of age. No information exists on anthrax vaccines in populations over the age of 65. It is critical that we assess the capacity of anthrax vaccines to generate a protective immune response in older individuals. In this study, we compared BioThrax® to a formulation containing a CpG adjuvant (AV7909).MethodsWe conducted a Phase 2 clinical study to evaluate safety and immunogenicity of three vaccination schedules of the AV7909 vaccine candidate and one vaccination schedule of BioThrax® vaccine in adults over 65 years of age. A total of 305 subjects were enrolled to assess safety and immunogenicity by seroprotection rates, toxin neutralizing antibody titers, and anti-Protective Antigen ELISA titers.ResultsCompared to BioThrax, AV7909 elicited a more robust immune response in older subjects, especially with three doses of AV7909 at Days 1, 15, and 29, or two doses at Days 1 and 29. These trends were true with both seroprotection rates as defined by the percentage of subjects with 50 percent neutralization factors greater than 0.56, and geometric mean antibody titers. The responses to both AV7909 and BioThax were lower in older subjects compared to those aged 18–50.ConclusionThe immunogenicity data suggest that the CpG adjuvant in the AV7909 vaccine helps to elicit a more robust immune response in subjects over the age of 65. Alternative dosing strategies may be considered in this population given the high seroprotection rates with Day 1 and 29, or Day 1, 15, and 29 regimens.Trial Registration: clinicaltrials.gov Identifier: NCT03518125.     

Preclinical evaluation of an investigational 21-valent pneumococcal conjugate vaccine,V116, in adult-rhesus monkey,rabbit, and mouse models

Despite the widespread effectiveness of pneumococcal conjugate vaccines on the overall incidence of invasive pneumococcal disease, the global epidemiological landscape continues to be transformed by residual disease from non-vaccine serotypes, thus highlighting the need for vaccines with expanded disease coverage. To address these needs, we have developed V116, an investigational 21-valent non-adjuvanted pneumococcal conjugate vaccine (PCV), containing pneumococcal polysaccharides (PnPs) 3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 15A, 16F, 17F, 19A, 20, 22F, 23A, 23B, 24F, 31, 33F, 35B, and a de-O-acetylated 15B (deOAc15B) individually conjugated to the nontoxic diphtheria toxoid CRM197 carrier protein. Preclinical studies evaluated the immunogenicity of V116 in adult monkeys, rabbits, and mice. Following one dose, V116 was found to be immunogenic in preclinical animal species and induced functional antibodies for all serotypes included in the vaccine, in addition to cross-reactive functional antibodies to serotypes 6C and 15B. In these preclinical animal studies, the increased valency of V116 did not result in serotype-specific antibody suppression when compared to lower valent vaccines V114 or PCV13. In addition, when compared with naïve controls, splenocytes from V116 to immunized animals demonstrated significant induction of CRM197-specific T cells in both IFN-γ and IL-4 ELISPOT assays, as well as Th1 and Th2 cytokine induction through in vitro stimulation assays, thus suggesting the ability of V116 to engage T cell dependent immune response pathways to aid in development of memory B cells. V116 also demonstrated significant protection in mice from intratracheal challenge with serotype 24F, a novel serotype not contained in any currently licensed vaccine.     

RelCoVax®, a two antigen subunit protein vaccine candidate against SARS-CoV-2 induces strong immune responses in mice

The COVID-19 pandemic has spurred an unprecedented movement to develop safe and effective vaccines against the SARS-CoV-2 virus to immunize the global population. The first set of vaccine candidates that received emergency use authorization targeted the spike (S) glycoprotein of the SARS-CoV-2 virus that enables virus entry into cells via the receptor binding domain (RBD). Recently, multiple variants of SARS-CoV-2 have emerged with mutations in S protein and the ability to evade neutralizing antibodies in vaccinated individuals. We have developed a dual RBD and nucleocapsid (N) subunit protein vaccine candidate named RelCoVax® through heterologous expression in mammalian cells (RBD) and E. coli (N). The RelCoVax® formulation containing a combination of aluminum hydroxide (alum) and a synthetic CpG oligonucleotide as adjuvants elicited high antibody titers against RBD and N proteins in mice after a prime and boost dose regimen administered 2 weeks apart. The vaccine also stimulated cellular immune responses with a potential Th1 bias as evidenced by increased IFN-γ release by splenocytes from immunized mice upon antigen exposure particularly N protein. Finally, the serum of mice immunized with RelCoVax® demonstrated the ability to neutralize two different SARS-CoV-2 viral strains in vitro including the Delta strain that has become dominant in many regions of the world and can evade vaccine induced neutralizing antibodies. These results warrant further evaluation of RelCoVax® through advanced studies and contribute towards enhancing our understanding of multicomponent subunit vaccine candidates against SARS-CoV-2.     

Seroprevalence of chronic hepatitis B virus infection and immunity to measles,rubella, tetanus and diphtheria among schoolchildren aged 6–7 years old in the Solomon Islands, 2016

The Western Pacific Region (WPR) established a goal to decrease chronic hepatitis B virus (HBV) infection among children to <1% and to achieve ≥95% hepatitis B vaccine birth dose (HepB-BD) and ≥95% three-dose (HepB3) coverage by 2017. In 2016, we conducted a national serosurvey in the Solomon Islands among 6–7-year-old school children to assess progress towards the control goal and immunity to measles, rubella, tetanus and diphtheria. Eighty schools were selected systematically proportional to their 6–7-year-old population; all 6–7-year-olds were enrolled. We collected basic demographic information and vaccination history. Children were tested for HBV surface antigen (HBsAg) using a rapid test, and for immunity to measles, rubella, tetanus, and diphtheria using a multiplex bead assay. In total, 1,249 out of 1,492 children (84%) were enrolled, among whom 1,169 (94%) underwent HBsAg testing and 1,156 (93%) provided dried blood spots. Almost 80% (n = 982) of enrolled children had vaccination cards, among whom 59% (n = 584) received a timely HepB-BD (within 24 hours of birth), 95% (n = 932) received HepB3, and >90% received vaccines for diphtheria, tetanus, and measles (rubella vaccine was not available at the time). HBsAg prevalence was 3.1% (95% confidence interval (CI): 2.0%–4.9%), with 55% of identified cases from one province. Among 982 children with vaccination cards, HBsAg prevalence was higher among children who had not received a timely HepB-BD and at least two HepB doses compared to those who had (4% vs. 2%). Of 1,156 tested children, immunoprotection estimates were 99% (95% CI: 98%–99%) for measles, 99% (95% CI: 97%–100%) for rubella, 85% (95% CI: 83%–87%) for tetanus, and 51% (95% CI: 47%–55%) for diphtheria. Improving timely HepB-BD coverage and maintaining high HepB3 coverage could help Solomon Islands reach the regional HBV control goal. Low immunity to tetanus and diphtheria suggests the need to introduce booster doses to ensure long-term protection.     

Hexavalent vaccines: What can we learn from head-to-head studies?

BackgroundThree hexavalent vaccines against diphtheria, tetanus, pertussis, poliomyelitis, hepatitis B virus (HBV), and Haemophilus influenzae type b (Hib) are licensed in Europe: Infanrix hexa (DT3aP-HBV-IPV/Hib), Hexyon (DT2aP-HBV-IPV-Hib) and Vaxelis (DT5aP-HBV-IPV-Hib).MethodsA systematic literature search was performed in various electronic databases to identify published peer-reviewed head-to-head studies comparing any licensed hexavalent vaccine to another.ResultsPredefined inclusion criteria were met by 12 articles. Individual studies concluded that the 3 hexavalent vaccines have acceptable safety profiles although some significant differences were observed in their reactogenicity profiles. The immunogenicity of DT2aP-HBV-IPV-Hib and DT5aP-HBV-IPV-Hib was non-inferior versus DT3aP-HBV-IPV/Hib. Some differences in immune responses to common antigens were observed, but their clinical relevance was not established. Anti-filamentous hemagglutinin (FHA) from pertussis and anti-polyribosylribitol phosphate (PRP) from Hib antibody concentrations tended to be higher, and anti-HBV and anti-pertussis toxin (PT) from pertussis antibody concentrations lower in DT2aP-HBV-IPV-Hib versus DT3aP-HBV-IPV/Hib vaccinees. Anti-PT and post-primary anti-PRP antibody concentrations tended to be higher, and anti-HBV, anti-FHA, anti-pertactin from pertussis and post-booster anti-PRP antibody concentrations lower in DT5aP-HBV-IPV-Hib versus DT3aP-HBV-IPV/Hib recipients. Slightly lower immune responses towards most vaccine antigens were observed with 2 + 1 versus 3 + 1 schedules post-primary vaccination, suggesting that 2 + 1 schedules should only be considered in countries with very high vaccination coverage.ConclusionAlthough the licensed hexavalent vaccines are generally considered similar, analyses of immunogenicity data from head-to-head trials highlighted differences that could be related to differences in composition and formulation. In addition, the demonstrated non-inferiority of the immunogenicity of the more recent vaccines versus DT3aP-HBV-IPV/Hib does not allow a full bridging to similar efficacy, effectiveness and safety. The availability of DT3aP-HBV-IPV/Hib over > 20 years allowed to collect a wealth of data on its long-term immunogenicity, safety and effectiveness in clinical and post-marketing studies, and makes it a key pillar of pediatric immunization.     

The STING activator c-di-AMP exerts superior adjuvant properties than the formulation poly(I:C)/CpG after subcutaneous vaccination with soluble protein antigen or DEC-205-mediated antigen targeting to dendritic cells

Vaccination is the most efficient strategy to protect from infectious diseases and the induction of a protective immune response not only depends on the nature of the antigen, but is also influenced by the vaccination strategy and the co-administration of adjuvants. Therefore, the precise monitoring of adjuvant candidates and their immune modulatory properties is a crucial step in vaccine development. Here, one central aspect is the induction of appropriate humoral and cellular effector mechanisms.In our study we performed a direct comparison of two promising candidates in adjuvant development, the STING activator bis-(3,5)-cyclic dimeric adenosine monophosphate (c-di-AMP) and the Toll-like receptor ligand formulation poly(I:C)/CpG. These were evaluated in C57BL/6 mice using the model antigen ovalbumin (OVA) in subcutaneous vaccination with soluble protein as well as in a dendritic cell (DC) targeting approach (αDEC-OVA). Strikingly, c-di-AMP as compared to poly(I:C)/CpG resulted in significantly higher antigen-specific IgG antibody levels when used in immunization with soluble OVA as well as in antigen targeting to DC. In vaccination with soluble OVA, c-di-AMP induced a significantly stronger CTL, Th1 and IFNγ-producing CD8⁺ memory T cell response than poly(I:C)/CpG. The response was CTL and Th1 cell dominated, a profile shared by both adjuvants. In the context of targeting OVA to DC, c-di-AMP induced significantly increased Th1 and Th2 cell responses as compared to poly(I:C)/CpG. Interestingly, the Th1 response dominated the overall T cell response only when c-di-AMP was used, indicating a distinct modulatory property of c-di-AMP when the DC targeting immunization approach was exploited.Taken together, we describe superior properties of c-di-AMP as compared to poly(I:C)/CpG in subcutaneous vaccination with soluble antigen as well as antigen targeting to DC. This indicates exceptionally effective adjuvant properties for c-di-AMP and provides compelling evidence of its potential for further adjuvant development, especially also when using DC targeting approaches.     

Dynamics of G2P[4] strain evolution and rotavirus vaccination: A review of evidence for Rotarix

Rotavirus (RV) gastroenteritis is a vaccine-preventable disease that creates high medical and economic burden in both developed and developing countries. Worldwide, more than 100 countries have introduced RV vaccines in their national immunization programs, and the remarkable impact of reducing the burden of severe childhood gastroenteritis has been unequivocally demonstrated. Currently, 2 oral vaccines (Rotarix, GSK and RotaTeq, Merck) are widely utilized. Recent temporary increases in the relative prevalence of G2P[4] RV strains have been observed in countries implementing RV vaccination. This comprehensive literature review aims to provide an insight on RV genotype evolution in the context of mass vaccination with Rotarix, particularly in the case of G2P[4]. In the post-vaccine era, strain surveillance data indicated temporal and spatial changes in countries both with and without RV vaccination programs. Annual fluctuations in G2P[4] prevalence seem to occur naturally, with no substantial differences between countries using Rotarix, RotaTeq or mixed vaccination programs. Moreover, Rotarix has been shown to be efficacious and effective against gastroenteritis caused by non-vaccine strains, including G2P[4]. These data indicate that shifts in RV genotype distribution are likely to constitute an inherent process of virus evolution to infect the human gut. Following RV vaccine introduction, incidences of RV gastroenteritis declined dramatically and mass vaccination will likely maintain this status, despite possible fluctuations in the relative distribution of genotypes. There is no conclusive evidence of unusual burst of new or vaccine-escape strains since global RV vaccines use. The emergence of strains with a potential to increase the current burden of RV disease should be continuously monitored and can only be established by exhaustive characterization of strains, including whole genomic sequencing. Given the natural fluctuations in RV strains over time, caution is advised when interpreting temporal changes in RV strain dynamics, as they could mistakenly be attributed to vaccination.     

Concomitant administration of a liquid formulation of human rotavirus vaccine (porcine circovirus-free) with routine childhood vaccines in infants in the United States: Results from a phase 3, randomized trial

BackgroundIn response to the detection of porcine circovirus type 1 (PCV-1) in the human rotavirus vaccine (HRV), a PCV-free HRV (no detection of PCV-1 and PCV-2 according to the detection limit of tests used) was developed. Liquid (Liq) PCV-free HRV previously showed immunogenicity and safety profiles comparable to lyophilized (Lyo) HRV.MethodsThis was a phase 3a, randomized, single-blind study (NCT03207750) conducted in the United States. Healthy infants aged 6–12 weeks received 2 doses (0, 2 months) of either Liq PCV-free HRV or Lyo HRV with routine vaccines (0, 2, 4 months): diphtheria-tetanus-acellular pertussis, hepatitis B and inactivated poliovirus combination vaccine (DTaP-HBV-IPV), monovalent tetanus toxoid-conjugated vaccine against Haemophilus influenzae type b (Hib-TT), and 13-valent pneumococcal conjugate vaccine. Co-primary objectives were: (i) to assess non-inferiority of immune responses to routine vaccine antigens 1 month post-dose 3 following co-administration with Liq PCV-free HRV compared to Lyo HRV; (ii) to rule out a 10% decrease in seroresponse to pertussis antigens after dose 3. Other objectives were to evaluate immunogenicity and safety of HRV vaccines.ResultsOf 1272 vaccinated infants, 990 (489 in Liq PCV-free HRV and 501 in Lyo HRV group) were included in the per-protocol set. All statistical criteria were met, thus co-primary objectives were demonstrated. Seroprotection/seropositivity rates in both groups were high: 100% for diphtheria/tetanus, ≥99.3% for HBV, ≥99.8% for polio, ≥99.8% for each pertussis antigen, ≥90.8% for all pneumococcal serotypes except serotype 3 (≥69.1%), and ≥ 97.4% for Hib. Most infants seroconverted for anti-RV antibodies (76.3% of Liq PCV-free HRV and 78.9% of Lyo HRV recipients). Geometric mean concentrations/titers were comparable between groups. Incidences of adverse events and serious adverse events were similar between groups.ConclusionRoutine pediatric vaccines co-administered with Liq PCV-free HRV showed non-inferior immune responses and similar safety profiles to those following co-administration with Lyo HRV.     

Common issues and improvement solution of vaccine hesitancy in children with underlying neurological conditions: Experience from one National Children’s Medical Center in China

BackgroundParents and healthcare providers usually defer or avoid immunization for children with neurological conditions. This study was conducted to investigate the common issues of immunization among these special children and the impact of specialists’ recommendation on improving immunization practice.MethodWe included 2,221 children with underlying neurological conditions seeking vaccination consultation at the first Immunization Advisory Clinic in China during 2017–2019. The primary neurological conditions and immunization status were analyzed. All parents were informed to self-report the adverse events following catch-up immunization. For specially concerned children with hereditary disorders, immune-related encephalopathy and epilepsy, we conducted the active follow-up to monitor the compliance with recommendation and the adverse events.ResultAll counselling children were assessed as not having any contraindication of immunization. A total of 2,019 (90.9%) children with underlying neurological conditions had delayed immunization and 99 (4.5%) had non-immunization. The coverage rate of age-appropriate vaccines was 56.1%. The most concerned vaccines were diphtheria, tetanus and acellular pertussis combined vaccine, diphtheria and tetanus combined vaccine, meningococcal polysaccharide vaccine and Japanese encephalitis vaccine. Resuming immunization was recommended for the 2,048 (92.2%) children. Most of counselling children complied with the specialists’ recommendation. Neither progress nor flaring of the neurological medical conditions was reported from parents.ConclusionVaccine hesitancy was a common issue for Chinese children with all kinds of neurological conditions. Specialized consultation on immunization is helpful to build vaccine confidence for the special children. Immunization for children with underlying neurological conditions is generally safe.     

Oral vaccine of recombinant Lactococcus lactis expressing the VP1 protein of duck hepatitis A virus type 3 induces mucosal and systemic immune responses

Duck hepatitis A virus (DHAV) is the major pathogen of duck viral hepatitis, which has caused great economic losses to duck breeding industry. As an effective delivery tool for protein antigens, Lactococcus lactis (L. lactis) has been successfully used to stimulate mucosal and systemic immune response. In this study, a recombinant L. lactis named NZ3900-VP1 was constructed, which could express VP1 protein of DHAV type 3 (DHAV-3) by using a nisin-controlled expression (NICE) system. The animal experiment in both mice and ducklings were performed to detect the immune response and protection effect of oral vaccination by the recombinant L. lactis. The results showed that oral vaccination with L. lactis NZ3900-VP1 significantly induced specific anti-VP1 IgG antibodies and mucosal secretory immunoglobulin A (sIgA) of DHAV-3 in mice and ducklings, and cytokines including interleukin-2 (IL-2), interferon gamma (IFN-γ), interleukin-10 (IL-10) and interleukin-4 (IL-4). Notably, the ducklings vaccinated with L. lactis NZ3900-VP1 were effectively protected when facing natural infestation of DHAV-3, which indicated that the recombinant L. lactis could serve as an effective vaccine to prevent DHAV-3 infection in ducklings.     

Immunogenicity and safety of the RTS,S/AS01 malaria vaccine co-administered with measles,rubella and yellow fever vaccines in Ghanaian children: A phase IIIb,multi-center,non-inferiority,randomized, open,controlled trial

BackgroundTo optimize vaccine implementation visits for young children, it could be efficient to administer the first RTS,S/AS01 malaria vaccine dose during the Expanded Programme on Immunization (EPI) visit at 6 months of age together with Vitamin A supplementation and the third RTS,S/AS01 dose on the same day as yellow fever (YF), measles and rubella vaccines at 9 months of age. We evaluated the safety and immunogenicity of RTS,S/AS01 when co-administered with YF and combined measles-rubella (MR) vaccines.MethodsIn this phase 3b, open-label, controlled study (NCT02699099), 709 Ghanaian children were randomized (1:1:1) to receive RTS,S/AS01 at 6, 7.5 and 9 months of age, and YF and MR vaccines at 9 or 10.5 months of age (RTS,S coad and RTS,S alone groups, respectively). The third group received YF and MR vaccines at 9 months of age and will receive RTS,S/AS01 at 10.5, 11.5 and 12.5 months of age (Control group). All children received Vitamin A at 6 months of age. Non-inferiority of immune responses to the vaccine antigens was evaluated 1 month following co-administration versus RTS,S/AS01 or EPI vaccines (YF and MR vaccines) alone using pre-defined non-inferiority criteria. Safety was assessed until Study month 4.5.ResultsNon-inferiority of antibody responses to the anti-circumsporozoite and anti-hepatitis B virus surface antigens when RTS,S/AS01 was co-administered with YF and MR vaccines versus RTS,S/AS01 alone was demonstrated. Non-inferiority of antibody responses to the measles, rubella, and YF antigens when RTS,S/AS01 was co-administered with YF and MR vaccines versus YF and MR vaccines alone was demonstrated. The safety profile of all vaccines was clinically acceptable in all groups.ConclusionsRTS,S/AS01 can be co-administered with Vitamin A at 6 months and with YF and MR vaccines at 9 months of age during EPI visits, without immune response impairment to any vaccine antigen or negative safety effect.     

Therapeutic vaccines for amyotrophic lateral sclerosis directed against disease specific epitopes of superoxide dismutase 1

Emerging evidence suggests seeding and prion-like propagation of mutant Superoxide Dismutase 1 (SOD1) misfolding to be a potential mechanism for ALS pathogenesis and progression. Immuno-targeting of misfolded SOD1 has shown positive clinical outcomes in mutant SOD1 transgenic mice. However, a major challenge in developing active immunotherapies for proteinopathies such as ALS is the design of immunogens enabling exclusive recognition of pathogenic species of a self-protein. Ideally, one would achieve a robust antibody response against the disease-misfolded protein while sparing the natively folded conformer to avoid inducing deleterious autoimmune complications, or inhibiting its normal function. Using a motor neuron disease mouse model expressing human SOD1-G37R, we herein report the immunogenicity and therapeutic efficacy of two ALS vaccines, tgG-DSE2lim and tgG-DSE5b, based on the notion that native SOD1 would undergo early unfolding in disease to present “disease specific epitopes” (DSE). Both vaccines elicited rapid, robust, and well-sustained epitope-specific antibody responses with a desirable Th2-biased immune response. Both vaccines significantly extended the life expectancy of hSOD1^G37R mice, with tgG-DSE2lim displaying greater protection than tgG-DSE5b at earlier pre-symptomatic stage. tgG-DSE5b, but not tgG-DSE2lim, significantly delayed disease onset and appreciably slowed disease progression. This implies that conformationally distinct species of misfolded SOD1 may derive from the same mutation, thereby modifying disease phenotypes in a different fashion. Our results validate the rationale for conformation-based immuno-targeting of misfolded SOD1 as a promising therapeutic strategy to slow or even halt disease progression in familial ALS associated with SOD1 mutations, as well as a prophylactic intervention for carriers of SOD1 mutations. Our study not only provides important proof-of-principle data for the development of a safe and effective human therapeutic/prophylactic ALS vaccine against misfolded SOD1, but also predicts a great potential to extend our DSE-based vaccination approach to other types of ALS, such as those associated with TDP-43 proteinopathies.     

Effect of immune regulatory pathways after immunization with GMZ2 malaria vaccine candidate in healthy lifelong malaria-exposed adults

BackgroundDespite appreciable immunogenicity in malaria-naive populations, many candidate malaria vaccines are considerably less immunogenic in malaria-exposed populations. This could reflect induction of immune regulatory mechanisms involving Human Leukocyte Antigen G (HLA-G), regulatory T (Treg), and regulatory B (Breg) cells. Here, we addressed the question whether there is correlation between these immune regulatory pathways and both plasmablast frequencies and vaccine-specific IgG concentrations.MethodsFifty Gabonese adults with lifelong exposure to Plasmodium spp were randomized to receive three doses of either 30 µg or 100 µg GMZ2-CAF01, or 100 µg GMZ2-alum, or control vaccine (rabies vaccine) at 4-week intervals. Only plasma and peripheral blood mononuclear cells isolated from blood samples collected before (D0) and 28 days after the third vaccination (D84) of 35 participants were used to measure sHLA-G levels and anti-GMZ2 IgG concentrations, and to quantify Treg, Breg and plasmablast cells. Vaccine efficacy was assessed using controlled human malaria infection (CHMI) by direct venous inoculation of Plasmodium falciparum sporozoites (PfSPZ Challenge).ResultsThe sHLA-G concentration increased from D0 to D84 in all GMZ2 vaccinated participants and in the control group, whereas Treg frequencies increased only in those receiving 30 µg or 100 µg GMZ2-CAF01. The sHLA-G level on D84 was associated with a decrease of the anti-GMZ2 IgG concentration, whereas Treg frequencies on D0 or on D84, and Breg frequency on D84 were associated with lower plasmablast frequencies. Importantly, having a D84:D0 ratio of sHLA-G above the median was associated with an increased risk of P. falciparum infection after sporozoites injection.ConclusionRegulatory immune responses are induced following immunization. Stronger sHLA-G and Treg immune responses may suppress vaccine induced immune responses, and the magnitude of the sHLA-G response increased the risk of Plasmodium falciparum infection after CHMI. These findings could have implications for the design and testing of malaria vaccine candidates in semi-immune individuals.     

Single-replication BM2SR vaccine provides sterilizing immunity and cross-lineage influenza B virus protection in mice

Both influenza A and B viruses cause outbreaks of seasonal influenza resulting in significant morbidity and mortality. There are two antigenically distinct lineages of influenza B virus, Yamagata lineage (YL) and Victoria lineage (VL). Since both B lineages have been co-circulating for years, more than 70% of influenza vaccines currently manufactured are quadrivalent consisting of influenza A (H1N1), influenza A (H3N2), influenza B (YL) and influenza B (VL) antigens. Although quadrivalent influenza vaccines tend to elevate immunity to both influenza B lineages, estimated overall vaccine efficacy against influenza B is still only around 42%. Thus, a more effective influenza B vaccine is needed.To meet this need, we generated BM2-deficient, single-replication (BM2SR) influenza B vaccine viruses that encode surface antigens from influenza B/Wisconsin/01/2010 (B/WI01, YL) and B/Brisbane/60/2008 (B/Bris60, VL) viruses. The BM2SR-WI01 and BM2SR-Bris60 vaccine viruses are replication-deficient in vitro and in vivo, and can only replicate in a cell line that expresses the complementing BM2 protein. Both BM2SR viruses were non-pathogenic to mice, and vaccinated animals showed elevated mucosal and serum antibody responses to both Yamagata and Victoria lineages in addition to cellular responses. Serum antibody responses included lineage-specific hemagglutinin inhibition antibody (HAI) responses as well as responses to the stem region of the hemagglutinin (HA). BM2SR vaccine viruses provided apparent sterilizing immunity to mice against intra- and inter-lineage drifted B virus challenge. The data presented here support the feasibility of BM2SR as a platform for next-generation trivalent influenza vaccine development.