Efficacy and Safety of a Recombinant Plant-Based Adjuvanted Covid-19 Vaccine.

BACKGROUND: Coronavirus-like particles (CoVLP) that are produced in plants and display the prefusion spike glycoprotein of the original strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are combined with an adjuvant (Adjuvant System 03 [AS03]) to form the candidate vaccine. METHODS: In this phase 3, multinational, randomized, placebo-controlled trial conducted at 85 centers, we assigned adults (≥18 years of age) in a 1:1 ratio to receive two intramuscular injections of the CoVLP+AS03 vaccine or placebo 21 days apart. The primary objective of the trial was to determine the efficacy of the CoVLP+AS03 vaccine in preventing symptomatic coronavirus disease 2019 (Covid-19) beginning at least 7 days after the second injection, with the analysis performed after the detection of at least 160 cases. RESULTS: A total of 24,141 volunteers participated in the trial; the median age of the participants was 29 years. Covid-19 was confirmed by polymerase-chain-reaction assay in 165 participants in the intention-to-treat population; all viral samples that could be sequenced contained variants of the original strain. Vaccine efficacy was 69.5% (95% confidence interval [CI], 56.7 to 78.8) against any symptomatic Covid-19 caused by five variants that were identified by sequencing. In a post hoc analysis, vaccine efficacy was 78.8% (95% CI, 55.8 to 90.8) against moderate-to-severe disease and 74.0% (95% CI, 62.1 to 82.5) among the participants who were seronegative at baseline. No severe cases of Covid-19 occurred in the vaccine group, in which the median viral load for breakthrough cases was lower than that in the placebo group by a factor of more than 100. Solicited adverse events were mostly mild or moderate and transient and were more frequent in the vaccine group than in the placebo group; local adverse events occurred in 92.3% and 45.5% of participants, respectively, and systemic adverse events in 87.3% and 65.0%. The incidence of unsolicited adverse events was similar in the two groups up to 21 days after each dose (22.7% and 20.4%) and from day 43 through day 201 (4.2% and 4.0%). CONCLUSIONS: The CoVLP+AS03 vaccine was effective in preventing Covid-19 caused by a spectrum of variants, with efficacy ranging from 69.5% against symptomatic infection to 78.8% against moderate-to-severe disease. (Funded by Medicago; ClinicalTrials.gov number, NCT04636697.).

A Phase 2 Clinical Trial to Evaluate the Safety, Reactogenicity, and Immunogenicity of Different Prime-Boost Vaccination Schedules of 2013 and 2017 A(H7N9) Inactivated Influenza Virus Vaccines Administered With and Without AS03 Adjuvant in Healthy US Adults.

INTRODUCTION: A surge of human influenza A(H7N9) cases began in 2016 in China from an antigenically distinct lineage. Data are needed about the safety and immunogenicity of 2013 and 2017 A(H7N9) inactivated influenza vaccines (IIVs) and the effects of AS03 adjuvant, prime-boost interval, and priming effects of 2013 and 2017 A(H7N9) IIVs. METHODS: Healthy adults (n = 180), ages 19-50 years, were enrolled into this partially blinded, randomized, multicenter phase 2 clinical trial. Participants were randomly assigned to 1 of 6 vaccination groups evaluating homologous versus heterologous prime-boost strategies with 2 different boost intervals (21 vs 120 days) and 2 dosages (3.75 or 15 µg of hemagglutinin) administered with or without AS03 adjuvant. Reactogenicity, safety, and immunogenicity measured by hemagglutination inhibition and neutralizing antibody titers were assessed. RESULTS: Two doses of A(H7N9) IIV were well tolerated, and no safety issues were identified. Although most participants had injection site and systemic reactogenicity, these symptoms were mostly mild to moderate in severity; injection site reactogenicity was greater in vaccination groups receiving adjuvant. Immune responses were greater after an adjuvanted second dose, and with a longer interval between prime and boost. The highest hemagglutination inhibition geometric mean titer (95% confidence interval) observed against the 2017 A(H7N9) strain was 133.4 (83.6-212.6) among participants who received homologous, adjuvanted 3.75 µg + AS03/2017 doses with delayed boost interval. CONCLUSIONS: Administering AS03 adjuvant with the second H7N9 IIV dose and extending the boost interval to 4 months resulted in higher peak antibody responses. These observations can broadly inform strategic approaches for pandemic preparedness. Clinical Trials Registration. NCT03589807.

Water-in-oil adjuvant challenges in fish vaccination: An experimental inactivated adjuvanted vaccine against betanodavirus infection in Senegalese sole.

The extensive growth of intensive fish farming has led to a massive spread of infectious diseases. Nervous necrosis virus (NNV) is the causative agent of the viral encephalo- and retinopathy disease which has become a major threat for fish farming all over the globe. The devastating mortality rates recorded in disease outbreaks, especially when infected specimens are at early stages of development, have a high economic impact on the sector. Currently, vaccines are the most cost-effective preventing tool in the fight against viruses. Inactivated vaccines have the advantage of simplicity in their development at the same time as present the antigen in a similar manner than the natural infection in the host. Nevertheless, they usually trigger weaker immune responses needing adjuvants to boost their effectiveness. In this work, we have intraperitoneally vaccinated Senegalese sole juveniles (Solea senegalensis) with a previously designed inactivated vaccine against NNV based on binary ethylenimine (BEI), mixed or not with an oil-adjuvant. Our results demonstrated the potential activation of different immune pathways when the vaccine was administered alone compared to the oil-adjuvanted vaccine, both resulting in an equivalent partial improvement in survival following a NNV challenge. However, whilst the vaccine alone led to a significant increase in specific antibodies, in the adjuvanted version those antibodies were kept basal although with a slight improvement in their neutralization capacity. At transcriptional level, neither vaccine (adjuvanted or not) triggered the immune system activation during the vaccination period. However, after NNV infection, the BEI-inactivated vaccines alone and oil-adjuvanted both elicited the stimulation of antiviral responsive genes (rtp3, herc4), antigen presentation molecules (mhcii) and T-cell markers (cd8a) in the head-kidney. Additionally, the oil-adjuvanted vaccine appears to stimulate mediator cytokines (il6) and B-cell markers (ight and ighm). Surprisingly, when the adjuvant was administered alone, fish showed the highest survival rates concomitantly with a lack of NNV-IgM production, pointing to the possible induction of different immune pathways than the B-cell responses via antibodies by the adjuvant. Since this combined vaccine did not succeed in the full extension of protection against the pathogen, further studies should be performed focusing on unravelling the molecular mechanisms through which adjuvants trigger the immune response, both independently and when added to a vaccine antigen.

Immunogenicity, safety, and reactogenicity of heterologous COVID-19 primary vaccination incorporating mRNA, viral-vector, and protein-adjuvant vaccines in the UK (Com-COV2): a single-blind, randomised, phase 2, non-inferiority trial.

BACKGROUND: Given the importance of flexible use of different COVID-19 vaccines within the same schedule to facilitate rapid deployment, we studied mixed priming schedules incorporating an adenoviral-vectored vaccine (ChAdOx1 nCoV-19 [ChAd], AstraZeneca), two mRNA vaccines (BNT162b2 [BNT], Pfizer-BioNTech, and mRNA-1273 [m1273], Moderna) and a nanoparticle vaccine containing SARS-CoV-2 spike glycoprotein and Matrix-M adjuvant (NVX-CoV2373 [NVX], Novavax). METHODS: Com-COV2 is a single-blind, randomised, non-inferiority trial in which adults aged 50 years and older, previously immunised with a single dose of ChAd or BNT in the community, were randomly assigned (in random blocks of three and six) within these cohorts in a 1:1:1 ratio to receive a second dose intramuscularly (8-12 weeks after the first dose) with the homologous vaccine, m1273, or NVX. The primary endpoint was the geometric mean ratio (GMR) of serum SARS-CoV-2 anti-spike IgG concentrations measured by ELISA in heterologous versus homologous schedules at 28 days after the second dose, with a non-inferiority criterion of the GMR above 0·63 for the one-sided 98·75% CI. The primary analysis was on the per-protocol population, who were seronegative at baseline. Safety analyses were done for all participants who received a dose of study vaccine. The trial is registered with ISRCTN, number 27841311. FINDINGS: Between April 19 and May 14, 2021, 1072 participants were enrolled at a median of 9·4 weeks after receipt of a single dose of ChAd (n=540, 47% female) or BNT (n=532, 40% female). In ChAd-primed participants, geometric mean concentration (GMC) 28 days after a boost of SARS-CoV-2 anti-spike IgG in recipients of ChAd/m1273 (20 114 ELISA laboratory units [ELU]/mL [95% CI 18 160 to 22 279]) and ChAd/NVX (5597 ELU/mL [4756 to 6586]) was non-inferior to that of ChAd/ChAd recipients (1971 ELU/mL [1718 to 2262]) with a GMR of 10·2 (one-sided 98·75% CI 8·4 to ∞) for ChAd/m1273 and 2·8 (2·2 to ∞) for ChAd/NVX, compared with ChAd/ChAd. In BNT-primed participants, non-inferiority was shown for BNT/m1273 (GMC 22 978 ELU/mL [95% CI 20 597 to 25 636]) but not for BNT/NVX (8874 ELU/mL [7391 to 10 654]), compared with BNT/BNT (16 929 ELU/mL [15 025 to 19 075]) with a GMR of 1·3 (one-sided 98·75% CI 1·1 to ∞) for BNT/m1273 and 0·5 (0·4 to ∞) for BNT/NVX, compared with BNT/BNT; however, NVX still induced an 18-fold rise in GMC 28 days after vaccination. There were 15 serious adverse events, none considered related to immunisation. INTERPRETATION: Heterologous second dosing with m1273, but not NVX, increased transient systemic reactogenicity compared with homologous schedules. Multiple vaccines are appropriate to complete primary immunisation following priming with BNT or ChAd, facilitating rapid vaccine deployment globally and supporting recognition of such schedules for vaccine certification. FUNDING: UK Vaccine Task Force, Coalition for Epidemic Preparedness Innovations (CEPI), and National Institute for Health Research. NVX vaccine was supplied for use in the trial by Novavax.

A Novel Prophylaxis Strategy Using Liposomal Vaccine Adjuvant CAF09b Protects against Influenza Virus Disease.

The SARS-CoV-2 pandemic caused a massive health and societal crisis, although the fast development of effective vaccines reduced some of the impact. To prepare for future respiratory virus pandemics, a pan-viral prophylaxis could be used to control the initial virus outbreak in the period prior to vaccine approval. The liposomal vaccine adjuvant CAF®09b contains the TLR3 agonist polyinosinic:polycytidylic acid, which induces a type I interferon (IFN-I) response and an antiviral state in the affected tissues. When testing CAF09b liposomes as a potential pan-viral prophylaxis, we observed that intranasal administration of CAF09b liposomes to mice resulted in an influx of innate immune cells into the nose and lungs and upregulation of IFN-I-related gene expression. When CAF09b liposomes were administered prior to challenge with mouse-adapted influenza A/Puerto Rico/8/1934 virus, it protected from severe disease, although the virus was still detectable in the lungs. However, when CAF09b liposomes were administered after influenza challenge, the mice had a similar disease course to controls. In conclusion, CAF09b may be a suitable candidate as a pan-viral prophylactic treatment for epidemic viruses, but must be administered prior to virus exposure to be effective.

Intranasal Immunization for Zika in a Pre-Clinical Model.

Humans continue to be at risk from the Zika virus. Although there have been significant research advancements regarding Zika, the absence of a vaccine or approved treatment poses further challenges for healthcare providers. In this study, we developed a microparticulate Zika vaccine using an inactivated whole Zika virus as the antigen that can be administered pain-free via intranasal (IN) immunization. These microparticles (MP) were formulated using a double emulsion method developed by our lab. We explored a prime dose and two-booster-dose vaccination strategy using MPL-A® and Alhydrogel® as adjuvants to further stimulate the immune response. MPL-A® induces a Th1-mediated immune response and Alhydrogel® (alum) induces a Th2-mediated immune response. There was a high recovery yield of MPs, less than 5 µm in size, and particle charge of -19.42 ± 0.66 mV. IN immunization of Zika MP vaccine and the adjuvanted Zika MP vaccine showed a robust humoral response as indicated by several antibodies (IgA, IgM, and IgG) and several IgG subtypes (IgG1, IgG2a, and IgG3). Vaccine MP elicited a balance Th1- and Th2-mediated immune response. Immune organs, such as the spleen and lymph nodes, exhibited a significant increase in CD4+ helper and CD8+ cytotoxic T-cell cellular response in both vaccine groups. Zika MP vaccine and adjuvanted Zika MP vaccine displayed a robust memory response (CD27 and CD45R) in the spleen and lymph nodes. Adjuvanted vaccine-induced higher Zika-specific intracellular cytokines than the unadjuvanted vaccine. Our results suggest that more than one dose or multiple doses may be necessary to achieve necessary immunological responses. Compared to unvaccinated mice, the Zika vaccine MP and adjuvanted MP vaccine when administered via intranasal route demonstrated robust humoral, cellular, and memory responses. In this pre-clinical study, we established a pain-free microparticulate Zika vaccine that produced a significant immune response when administered intranasally.

Poly I:C elicits broader and stronger humoral and cellular responses to a Plasmodium vivax circumsporozoite protein malaria vaccine than Alhydrogel in mice.

Malaria remains a global health challenge, necessitating the development of effective vaccines. The RTS,S vaccination prevents Plasmodium falciparum (Pf) malaria but is ineffective against Plasmodium vivax (Pv) disease. Herein, we evaluated the murine immunogenicity of a recombinant PvCSP incorporating prevalent polymorphisms, adjuvanted with Alhydrogel or Poly I:C. Both formulations induced prolonged IgG responses, with IgG1 dominance by the Alhydrogel group and high titers of all IgG isotypes by the Poly I:C counterpart. Poly I:C-adjuvanted vaccination increased splenic plasma cells, terminally-differentiated memory cells (MBCs), and precursors relative to the Alhydrogel-combined immunization. Splenic B-cells from Poly I:C-vaccinated mice revealed an antibody-secreting cell- and MBC-differentiating gene expression profile. Biological processes such as antibody folding and secretion were highlighted by the Poly I:C-adjuvanted vaccination. These findings underscore the potential of Poly I:C to strengthen immune responses against Pv malaria.

A broadly applicable protein-polymer adjuvant system for antiviral vaccines.

Although protein subunit vaccines generally have acceptable safety profiles with precise antigenic content, limited immunogenicity can lead to unsatisfactory humoral and cellular immunity and the need for vaccine adjuvants and delivery system. Herein, we assess a vaccine adjuvant system comprising Quillaja Saponaria-21(QS-21) and cobalt porphyrin polymeric micelles that enabling the display of His-tagged antigen on its surface. The nanoscale micelles promote antigen uptake and dendritic cell activation to induce robust cytotoxic T lymphocyte response and germinal center formation. Using the recombinant protein antigens from influenza A and rabies virus, the micelle adjuvant system elicited robust antiviral responses and protected mice from lethal challenge. In addition, this system could be combined with other antigens to induce high titers of neutralizing antibodies in models of three highly pathogenic viral pathogens: Ebola virus, Marburg virus, and Nipah virus. Collectively, our results demonstrate this polymeric micelle adjuvant system can be used as a potent nanoplatform for developing antiviral vaccine countermeasures that promote humoral and cellular immunity.

Safety and Immunogenicity of a DNA Vaccine With Subtype C gp120 Protein Adjuvanted With MF59 or AS01B: A Phase 1/2a HIV-1 Vaccine Trial.

BACKGROUND: An effective vaccine is required to end the HIV pandemic. We evaluated the safety and immunogenicity of a DNA (DNA-HIV-PT123) vaccine with low- or high-dose bivalent (TV1.C and 1086.C glycoprotein 120) subtype C envelope protein combinations, adjuvanted with MF59 or AS01B. METHODS: HIV Vaccine Trials Network (HVTN)108 was a randomized, placebo-controlled, double-blind, phase 1/2a trial conducted in the United States and South Africa. HIV-negative adults were randomly assigned to 1 of 7 intervention arms or placebo to assess DNA prime with DNA/protein/adjuvant boosts, DNA/protein/adjuvant co-administration, and low-dose protein/adjuvant regimens. HVTN111 trial participants who received an identical regimen were also included. Outcomes included safety and immunogenicity 2 weeks and 6 months after final vaccination. RESULTS: From June 2016 to July 2018, 400 participants were enrolled (N = 334 HVTN108, N = 66 HVTN111); 370 received vaccine and 30 received placebo. There were 48 grade 3 and 3 grade 4 reactogenicity events among 39/400 (9.8%) participants, and 32 mild/moderate-related adverse events in 23/400 (5.8%) participants. All intervention groups demonstrated high IgG response rates (>89%) and high magnitudes to HIV-1 Env gp120 and gp140 proteins; response rates for AS01B-adjuvanted groups approached 100%. V1V2 IgG magnitude, Fc-mediated functions, IgG3 Env response rates, and CD4+ T-cell response magnitudes and rates were higher in the AS01B-adjuvanted groups. The AS01B-adjuvanted low-dose protein elicited greater IgG responses than the higher protein dose. CONCLUSIONS: The vaccine regimens were generally well tolerated. Co-administration of DNA with AS01B-adjuvanted bivalent Env gp120 elicited the strongest humoral responses; AS01B-adjuvanted regimens elicited stronger CD4+ T-cell responses, justifying further evaluation.ClinicalTrials.gov registration: NCT02915016, registered 26 September 2016.

Mastoparan-7 adjuvanted COBRA H1 and H3 hemagglutinin influenza vaccines.

Adjuvants enhance, prolong, and modulate immune responses by vaccine antigens to maximize protective immunity and enable more effective immunization in the young and elderly. Most adjuvants are formulated with injectable vaccines. However, an intranasal route of vaccination may induce mucosal and systemic immune responses for enhancing protective immunity in individuals and be easier to administer compared to injectable vaccines. In this study, a next generation of broadly-reactive influenza hemagglutinin (HA) vaccines were developed using the Computationally Optimized Broadly Reactive Antigen (COBRA) methodology. These HA vaccines were formulated with Mastoparan 7 (M7-NH2) mast cell degranulating peptide adjuvant and administered intranasally to determine vaccine-induced seroconversion of antibodies against a panel of influenza viruses and protection following infection with H1N1 and H3N2 viruses in mice. Mice vaccinated intranasally with M7-NH2-adjuvanted COBRA HA vaccines had high HAIs against a panel of H1N1 and H3N2 influenza viruses and were protected against both morbidity and mortality, with reduced viral lung titers, following challenge with an H1N1 influenza virus. Additionally, M7-NH2 adjuvanted COBRA HA vaccines induced Th2 skewed immune responses with robust IgG and isotype antibodies in the serum and mucosal lung lavages. Overall, this intranasally delivered M7-NH2 -adjuvanted COBRA HA vaccine provides effective protection against drifted H1N1 and H3N2 viruses.

Effects of different immunomodulating liposome-based adjuvants and injection sites on immunogenicity in pigs.

Vaccine adjuvants, such as liposome-based cationic adjuvant formulations (CAFs), are able to boost immune responses and, by incorporation of distinct immunomodulators, steer immunity towards a desired direction in mice, non-human primates and humans, while less studied in pigs. Here we used commercial pigs to investigate polarizing adjuvant effects of CAFs with immunomodulators: C-type lectin receptor ligands trehalose-6,6'-dibehenate and monomycolyl glycerol, toll-like receptor 3 ligand Poly(I:C) or retinoic acid. Vaccines were formulated with a recombinant Chlamydia model protein antigen and administered via three injection routes. All adjuvants significantly increased antigen-specific IgG in serum, compared to non-adjuvanted antigen. Administering the vaccines through intramuscular and intraperitoneal routes induced significantly higher antigen-specific IgG and IgA serum antibodies, than the perirectal route. Although immunizations triggered cell-mediated immunity, no significant differences between adjuvants or injection sites were detected. Genes depicting T cell subtypes revealed only minor differences. Our findings suggest that specific signatures of the tested adjuvant immunomodulation do not translate well from mice to pigs in standard two-dose immunizations. This study provides new insights into immune responses to CAFs in pigs, and highlights that adjuvant development should ideally be carried out in the intended species of interest or in models with high predictive validity/translational value.

Clinical development of SpikoGen®, an Advax-CpG55.2 adjuvanted recombinant spike protein vaccine.

Recombinant protein vaccines represent a well-established, reliable and safe approach for pandemic vaccination. SpikoGen® is a recombinant spike protein trimer manufactured in insect cells and formulated with Advax-CpG55.2 adjuvant. In murine, hamster, ferret and non-human primate studies, SpikoGen® consistently provided protection against a range of SARS-CoV-2 variants. A pivotal Phase 3 placebo-controlled efficacy trial involving 16,876 participants confirmed the ability of SpikoGen® to prevent infection and severe disease caused by the virulent Delta strain. SpikoGen® subsequently received a marketing authorization from the Iranian FDA in early October 2021 for prevention of COVID-19 in adults. Following a successful pediatric study, its approval was extended to children 5 years and older. Eight million doses of SpikoGen® have been delivered, and a next-generation booster version is currently in development. This highlights the benefits of adjuvanted protein-based approaches which should not overlook when vaccine platforms are being selected for future pandemics.

SpikoGen is a more traditional COVID-19 vaccine comprising SARS-CoV-2 spike protein extracellular domain formulated with Advax-CpG adjuvantSpikoGen differs from the Novavax vaccine in major ways including its use of the soluble secreted spike protein ECD rather than nanoparticle formulation and the use of a different adjuvantSpikoGen demonstrates robust protection against homologous and heterologous SARS-CoV-2 strains in hamster, ferret and non-human primate challenge modelsSpikoGen induces broadly cross-neutralizing antibodies, but still protects even after these antibody levels waneIn a pivotal Phase 3 clinical trial, SpikoGen reduced the risk of severe infection by 77.5% and was not associated with myocarditis, thrombosis or any other adverse safety signalsSpikoGen received an Emergency Use Authorization in the Middle East on 6 October 2021, making it the first recombinant spike protein vaccine to achieve this milestoneEight million doses of SpikoGen vaccine have been safely delivered to dateProtein-based vaccines have a long history of reliability and safety.

Hybrid response to SARS-CoV-2 and Neisseria meningitidis C after an OMV-adjuvanted immunization in mice and their offspring.

COVID-19, caused by SARS-CoV-2, and meningococcal disease, caused by Neisseria meningitidis, are relevant infectious diseases, preventable through vaccination. Outer membrane vesicles (OMVs), released from Gram-negative bacteria, such as N. meningitidis, present adjuvant characteristics and may confer protection against meningococcal disease. Here, we evaluated in mice the humoral and cellular immune response to different doses of receptor binding domain (RBD) of SARS-CoV-2 adjuvanted by N. meningitidis C:2a:P1.5 OMVs and aluminum hydroxide, as a combined preparation for these pathogens. The immunization induced IgG antibodies of high avidity for RBD and OMVs, besides IgG that recognized the Omicron BA.2 variant of SARS-CoV-2 with intermediary avidity. Cellular immunity showed IFN-γ and IL-4 secretion in response to RBD and OMV stimuli, demonstrating immunologic memory and a mixed Th1/Th2 response. Offspring presented transferred IgG of similar levels and avidity as their mothers. Humoral immunity did not point to the superiority of any RBD dose, but the group immunized with a lower antigenic dose (0.5 µg) had the better cellular response. Overall, OMVs enhanced RBD immunogenicity and conferred an immune response directed to N. meningitidis too.

Immunogenicity of intranasal vaccine based on SARS-CoV-2 spike protein during primary and booster immunizations in mice.

Mucosal immunity plays a crucial role in combating and controlling the spread of highly mutated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Recombinant subunit vaccines have shown safety and efficacy in clinical trials, but further investigation is necessary to evaluate their feasibility as mucosal vaccines. This study developed a SARS-CoV-2 mucosal vaccine using spike (S) proteins from a prototype strain and the omicron variant, along with a cationic chitosan adjuvant, and systematically evaluated its immunogenicity after both primary and booster immunization in mice. Primary immunization through intraperitoneal and intranasal administration of the S protein elicited cross-reactive antibodies against prototype strains, as well as delta and omicron variants, with particularly strong effects observed after mucosal vaccination. In the context of booster immunization following primary immunization with inactivated vaccines, the omicron-based S protein mucosal vaccine resulted in a broader and more robust neutralizing antibody response in both serum and respiratory mucosa compared to the prototype vaccine, enhancing protection against different variants. These findings indicate that mucosal vaccination with the S protein has the potential to trigger a broader and stronger antibody response during primary and booster immunization, making it a promising strategy against respiratory pathogens.

SARS-CoV-2 recombinant spike ferritin nanoparticle vaccine adjuvanted with Army Liposome Formulation containing monophosphoryl lipid A and QS-21: a phase 1, randomised, double-blind, placebo-controlled, first-in-human clinical trial.

BACKGROUND: A self-assembling SARS-CoV-2 WA-1 recombinant spike ferritin nanoparticle (SpFN) vaccine co-formulated with Army Liposomal Formulation (ALFQ) adjuvant containing monophosphoryl lipid A and QS-21 (SpFN/ALFQ) has shown protective efficacy in animal challenge models. This trial aims to assess the safety and immunogenicity of SpFN/ALFQ in a first-in-human clinical trial. METHODS: In this phase 1, randomised, double-blind, placebo-controlled, first-in-human clinical trial, adults were randomly assigned (5:5:2) to receive 25 µg or 50 µg of SpFN/ALFQ or saline placebo intramuscularly at day 1 and day 29, with an optional open-label third vaccination at day 181. Enrolment and randomisation occurred sequentially by group; randomisation was done by an interactive web-based randomisation system and only designated unmasked study personnel had access to the randomisation code. Adults were required to be seronegative and unvaccinated for inclusion. Local and systemic reactogenicity, adverse events, binding and neutralising antibodies, and antigen-specific T-cell responses were quantified. For safety analyses, exact 95% Clopper-Pearson CIs for the probability of any incidence of an unsolicited adverse event was computed for each group. For immunogenicity results, CIs for binary variables were computed using the exact Clopper-Pearson methodology, while CIs for geometric mean titres were based on 10 000 empirical bootstrap samples. Post-hoc, paired one-sample t tests were used to assess the increase in mean log-10 neutralising antibody titres between day 29 and day 43 (after the second vaccination) for the primary SARS-CoV-2 targets of interest. This trial is registered at ClinicalTrials.gov, NCT04784767, and is closed to new participants. FINDINGS: Between April 7, and June 29, 2021, 29 participants were enrolled in the study. 20 individuals were assigned to receive 25 µg SpFN/ALFQ, four to 50 µg SpFN/ALFQ, and five to placebo. Neutralising antibody responses peaked at day 43, 2 weeks after the second dose. Neutralisation activity against multiple omicron subvariants decayed more slowly than against the D614G or beta variants until 5 months after second vaccination for both dose groups. CD4+ T-cell responses were elicited 4 weeks after the first dose and were boosted after a second dose of SpFN/ALFQ for both dose groups. Neutralising antibody titres against early omicron subvariants and clade 1 sarbecoviruses were detectable after two immunisations and peaked after the third immunisation for both dose groups. Neutralising antibody titres against XBB.1.5 were detected after three vaccinations. Passive IgG transfer from vaccinated volunteers into Syrian golden hamsters controlled replication of SARS-CoV-1 after challenge. INTERPRETATION: SpFN/ALFQ was well tolerated and elicited robust and durable binding antibody and neutralising antibody titres against a broad panel of SARS-CoV-2 variants and other sarbecoviruses. FUNDING: US Department of Defense, Defense Health Agency.

ß­glucan vaccine adjuvant approach for cancer treatment through immune enhancement (B­VACCIEN) in specific immunocompromised populations (Review).

The incidence of cancer, which is the second leading cause of mortality globally, continues to increase, although continued efforts are being made to identify effective treatments with fewer side­effects. Previous studies have reported that chronic microinflammation, which occurs in diseases, including diabetes, along with weakened immune systems, may ultimately lead to cancer development. Chemotherapy, radiotherapy and surgery are the mainstream approaches to treatment; however, they all lead to immune system weakness, which in turn increases the metastatic spread. The aim of the present review was to provide evidence of a biological response modifier ß­glucan [ß­glucan vaccine adjuvant approach to treating cancer via immune enhancement (B­VACCIEN)] and its beneficial effects, including vaccine­adjuvant potential, balancing metabolic parameters (including blood glucose and lipid levels), increasing peripheral blood cell cytotoxicity against cancer and alleviating chemotherapy side effects in animal models. This suggests its value as a potential strategy to provide long­term prophylaxis in immunocompromised individuals or genetically prone to cancer.

Comparison of the safety and immunogenicity of a novel Matrix-M-adjuvanted nanoparticle influenza vaccine with a quadrivalent seasonal influenza vaccine in older adults: a phase 3 randomised controlled trial.

BACKGROUND: Improved seasonal influenza vaccines for older adults that can induce broadly cross-reactive antibodies and enhanced T-cell responses, particularly against A H3N2 viruses, while avoiding egg-adaptive antigenic changes, are needed. We aimed to show that the Matrix-M-adjuvanted quadrivalent nanoparticle influenza vaccine (qNIV) was immunologically non-inferior to a licensed, standard-dose quadrivalent inactivated influenza vaccine (IIV4) in older adults. METHODS: This was a phase 3 randomised, observer-blinded, active-comparator controlled trial done across 19 US community-based clinical research sites during the 2019-20 influenza season. Participants were clinically stable and community-dwelling, aged at least 65 years, and were randomised in a 1:1 ratio using an interactive web response system to receive a single intramuscular dose of qNIV or IIV4. The primary objective was to describe safety and show that qNIV was immunologically non-inferior to IIV4. The primary outcomes were adverse events by treatment group and comparative haemagglutination-inhibiting antibody responses (assayed with egg-propagated virus) on day 28, summarised in terms of the ratio of geometric mean titres (GMTRqNIV/IIV4) and seroconversion rate (SCR) difference between participants receiving qNIV or IIV4 for all four vaccine homologous influenza strains. The immunogenicity outcome was measured in the per-protocol population. Non-inferiority was shown if the lower bound of the two-sided 95% CI on the GMTRqNIV/IIV4 was at least 0·67 and the lower bound of the two-sided 95% CI on the SCR difference -was at least -10%. The study is registered with clinicaltrials.gov, NCT04120194, and is active and not recruiting. FINDINGS: 2742 adults were assessed for eligibility and 2654 were enrolled and randomised between Oct 14, 2019, and Oct 25, 2019; 1333 participants were randomised to the qNIV group and 1319 to the IIV4 group (two participants withdrew consent before being assigned to a group). qNIV showed immunological non-inferiority to IIV4: GMTRqNIV/IIV4 for the four vaccine homologous influenza strains was A/Brisbane 1·09 (95% CI 1·03 to 1·15), A/Kansas 1·19 (1·11 to 1·27), B/Maryland 1·03 (0·99 to 1·07), and B/Phuket 1·23 (1·16 to 1·29); and SCR difference was A/Brisbane 5·0 (95% CI 1·9 to 8·1), A/Kansas 7·3 (3·6 to 11·1), B/Maryland 0·5 (-1·9 to 2·9), and B/Phuket 8·5 (5·0 to 11·9). 659 (49·4%) of 1333 of participants in the qNIV group and 551 (41·8%) of 1319 participants in the IIV4 group had at least one treatment-emergent adverse event. More solicited adverse events were reported by participants in the qNIV group (551 [41·3%] of 1333) than in the IIV4 group (420 [31·8%] of 1319), and were comprised primarily of mild to moderate transient injection site pain (341 [25·6%] in the qNIV group vs 212 [16·1%] in the IIV4 group). INTERPRETATION: qNIV was well tolerated and produced qualitatively and quantitatively enhanced humoral and cellular immune response in older adults compared with IIV4. qNIV might enhance the effectiveness of seasonal influenza vaccination, and future studies to show clinical efficacy are planned. FUNDING: Novavax.

A two-dose optimum for recombinant S1 protein-based COVID-19 vaccination.

BACKGROUND: Recombinant protein subunit vaccination is considered to be a safe, fast and reliable technique when combating emerging and re-emerging diseases such as coronavirus disease 2019 (COVID-19). Typically, such subunit vaccines require the addition of adjuvants to attain adequate immunogenicity. AS01, which contains adjuvants MPL and saponin QS21, is a liposome-based vaccine adjuvant system that is one of the leading candidates. However, the adjuvant effect of AS01 in COVID-19 vaccines is not well described yet. METHODS: In this study, we utilized a mixture of AS01 as the adjuvant for an S1 protein-based COVID-19 vaccine. RESULTS: The adjuvanted vaccine induced robust immunoglobulin G (IgG) binding antibody and virus-neutralizing antibody responses. Importantly, two doses induced similar levels of IgG binding antibody and neutralizing antibody responses compared with three doses and the antibody responses weakened only slightly over time up to six weeks after immunization. CONCLUSION: These results suggested that two doses may be enough for a clinical vaccine strategy design using MPL & QS21 adjuvanted recombinant protein, especially in consideration of the limited production capacity of COVID-19 vaccine in a public health emergency.

Lipopolysaccharide Derived From the Lymphoid-Resident Commensal Bacteria Alcaligenes faecalis Functions as an Effective Nasal Adjuvant to Augment IgA Antibody and Th17 Cell Responses.

Alcaligenes spp., including A. faecalis, is a gram-negative facultative bacterium uniquely residing inside the Peyer's patches. We previously showed that A. faecalis-derived lipopolysaccharides (Alcaligenes LPS) acts as a weak agonist of toll-like receptor 4 to activate dendritic cells and shows adjuvant activity by enhancing IgG and Th17 responses to systemic vaccination. Here, we examined the efficacy of Alcaligenes LPS as a nasal vaccine adjuvant. Nasal immunization with ovalbumin (OVA) plus Alcaligenes LPS induced follicular T helper cells and germinal center formation in the nasopharynx-associated lymphoid tissue (NALT) and cervical lymph nodes (CLNs), and consequently enhanced OVA-specific IgA and IgG responses in the respiratory tract and serum. In addition, nasal immunization with OVA plus Alcaligenes LPS induced OVA-specific T cells producing IL-17 and/or IL-10, whereas nasal immunization with OVA plus cholera toxin (CT) induced OVA-specific T cells producing IFN-γ and IL-17, which are recognized as pathogenic type of Th17 cells. In addition, CT, but not Alcaligenes LPS, promoted the production of TNF-α and IL-5 by T cells. Nasal immunization with OVA plus CT, but not Alcaligenes LPS, led to increased numbers of neutrophils and eosinophils in the nasal cavity. Together, these findings indicate that the benign nature of Alcaligenes LPS is an effective nasal vaccine adjuvant that induces antigen-specific mucosal and systemic immune responses without activation of inflammatory cascade after nasal administration.

Evaluation of Microparticulate (S)-4,5-Dihydroxy-2,3-pentanedione (DPD) as a Potential Vaccine Adjuvant.

Adjuvants potentiate the immune response against co-inoculated antigens in the vaccine formulation. Based on the mechanism of action, the adjuvants are classified as immunostimulatory adjuvants and vaccine delivery systems. (S)-4,5-Dihydroxy-2,3-pentanedione (DPD) is the precursor of bacterial quorum sensing molecule, autoinducer (AI)-2. We tested the immunogenicity and adjuvant potential of microparticulate formulation of (S)-DPD via in vitro evaluation. By formulating the microparticles of (S)-DPD, we consolidated the advantages of both the classes of adjuvants. The microparticulate (S)-DPD was tested for its immunogenicity and cytotoxicity. We further tested its adjuvant effect by combining it with particulate vaccines for measles and gonorrhea and compared the adjuvant effect observed with the microparticulate formulations of the FDA-approved adjuvants alum, MPL A®, and MF59®. Microparticulate (S)-DPD was found to be non-cytotoxic towards the antigen-presenting cells and had an adjuvant effect with microparticulate gonorrhea vaccine. Further studies with additional bacterial vaccines and the in vivo evaluation will confirm the potential of microparticulate (S)-DPD as a probable vaccine adjuvant candidate.