Local and Systemic Immunity against Respiratory Syncytial Virus Induced by a Novel Intranasal Vaccine. A Randomized, Double-Blind, Placebo-controlled Clinical Trial

RATIONALE:Needle-free intranasal vaccines offer major potential advantages, especially against pathogens entering via mucosal surfaces. As yet, there is no effective vaccine against respiratory syncytial virus (RSV), a ubiquitous pathogen of global importance that preferentially infects respiratory epithelial cells; new strategies are urgently required. OBJECTIVES:Here, we report the safety and immunogenicity of a novel mucosal RSV F protein vaccine linked to an immunostimulatory bacterium-like particle (BLP). METHODS:In this phase I, randomised, double-blind placebo-controlled trial, 48 healthy volunteers aged 18-49 years were randomly assigned to receive placebo or SynGEM (low- or high-dose) intranasally by prime-boost administration. The primary outcome was safety and tolerability, with secondary objectives assessing virus-specific immunogenicity. MEASUREMENTS AND MAIN RESULTS:There were no significant differences in adverse events between placebo and vaccinated groups. SynGEM induced systemic plasmablast responses and significant, durable increases in RSV-specific serum antibody in healthy seropositive adults. Volunteers given low-dose SynGEM (140 µg F, 2mg BLP) required a boost at day 28 to achieve plateau responses with a maximum fold-change of 2.4, whereas high-dose recipients (350 µg F, 5mg BLP) achieved plateau responses with a fold-change of 1.5 after first vaccination that remained elevated up to 180 days post-vaccination irrespective of further boosting. Palivizumab-like antibodies were consistently induced, but F protein site Ø-specific antibodies were not detected and virus-specific nasal IgA responses were heterogeneous, with strongest responses in individuals with lower pre-existing antibody levels. CONCLUSIONS:SynGEM is thus the first non-replicating intranasal RSV subunit vaccine to induce persistent antibody responses in human volunteers. Clinical trial registration available at www.clinicaltrials.gov, ID NCT02958540

COVAC1 phase 2a expanded safety and immunogenicity study of a self-amplifying RNA vaccine against SARS-CoV-2

BACKGROUND: Lipid nanoparticle (LNP) encapsulated self-amplifying RNA (saRNA) is well tolerated and immunogenic in SARS-CoV-2 seronegative and seropositive individuals aged 18-75. METHODS: A phase 2a expanded safety and immunogenicity study of a saRNA SARS-CoV-2 vaccine candidate LNP-nCoVsaRNA, was conducted at participating centres in the UK between 10th August 2020 and 30th July 2021. Participants received 1 μg then 10 μg of LNP-nCoVsaRNA, ∼14 weeks apart. Solicited adverse events (AEs) were collected for one week post-each vaccine, and unsolicited AEs throughout. Binding and neutralisating anti-SARS-CoV-2 antibody raised in participant sera was measured by means of an anti-Spike (S) IgG ELISA, and SARS-CoV-2 pseudoneutralisation assay. (The trial is registered: ISRCTN17072692, EudraCT 2020-001646-20). FINDINGS: 216 healthy individuals (median age 51 years) received 1.0 μg followed by 10.0 μg of the vaccine. 28/216 participants were either known to have previous SARS-CoV2 infection and/or were positive for anti-Spike (S) IgG at baseline. Reactogenicity was as expected based on the reactions following licensed COVID-19 vaccines, and there were no serious AEs related to vaccination. 80% of baseline SARS-CoV-2 naïve individuals (147/183) seroconverted two weeks post second immunization, irrespective of age (18-75); 56% (102/183) had detectable neutralising antibodies. Almost all (28/31) SARS-CoV-2 positive individuals had increased S IgG binding antibodies following their first 1.0 μg dose with a ≥0.5log10 increase in 71% (22/31). INTERPRETATION: Encapsulated saRNA was well tolerated and immunogenic in adults aged 18-75 years. Seroconversion rates in antigen naïve were higher than those reported in our dose-ranging study. Further work is required to determine if this difference is related to a longer dosing interval (14 vs. 4 weeks) or dosing with 1.0 μg followed by 10.0 μg. Boosting of S IgG antibodies was observed with a single 1.0 μg injection in those with pre-existing immune responses. FUNDING: Grants and gifts from the Medical Research Council UKRI (MC_PC_19076), the National Institute for Health Research/Vaccine Task Force, Partners of Citadel and Citadel Securities, Sir Joseph Hotung Charitable Settlement, Jon Moulton Charity Trust, Pierre Andurand, and Restore the Earth

Enteropathogenic Escherichia coli Stimulates Effector-Driven Rapid Caspase-4 Activation in Human Macrophages

© 2019 The Author(s).Microbial infections can stimulate the assembly of inflammasomes, which activate caspase-1. The gastrointestinal pathogen enteropathogenic Escherichia coli (EPEC) causes localized actin polymerization in host cells. Actin polymerization requires the binding of the bacterial adhesin intimin to Tir, which is delivered to host cells via a type 3 secretion system (T3SS). We show that EPEC induces T3SS-dependent rapid non-canonical NLRP3 inflammasome activation in human macrophages. Notably, caspase-4 activation by EPEC triggers pyroptosis and cytokine processing through the NLRP3-caspase-1 inflammasome. Mechanistically, caspase-4 activation requires the detection of LPS and EPEC-induced actin polymerization, either via Tir tyrosine phosphorylation and the phosphotyrosine-binding adaptor NCK or Tir and the NCK-mimicking effector TccP. An engineered E. coli K12 could reconstitute Tir-intimin signaling, which is necessary and sufficient for inflammasome activation, ruling out the involvement of other virulence factors. Our studies reveal a crosstalk between caspase-4 and caspase-1 that is cooperatively stimulated by LPS and effector-driven actin polymerization.The authors would like to acknowledge grants from the Wellcome Trust (to G.F. and A.R.S.) and the MRC (to P.J.G., G.F., A.R.S., and the CMBI). Work in the laboratory of L.A.F. is funded by grant BIO2017-89081R from the Spanish Ministerio de Ciencia y Universidad (MICIU; AEI/FEDER, EU). G.F. and A.R.S. would like to acknowledge the MRC-funded High-Throughput Single-Cell Analysis facility at the CMBI

COVAC1 phase 2a expanded safety and immunogenicity study of a self-amplifying RNA vaccine against SARS-CoV-2Research in context

Summary: Background: Lipid nanoparticle (LNP) encapsulated self-amplifying RNA (saRNA) is well tolerated and immunogenic in SARS-CoV-2 seronegative and seropositive individuals aged 18–75. Methods: A phase 2a expanded safety and immunogenicity study of a saRNA SARS-CoV-2 vaccine candidate LNP-nCoVsaRNA, was conducted at participating centres in the UK between 10th August 2020 and 30th July 2021. Participants received 1 μg then 10 μg of LNP-nCoVsaRNA, ∼14 weeks apart. Solicited adverse events (AEs) were collected for one week post-each vaccine, and unsolicited AEs throughout. Binding and neutralisating anti-SARS-CoV-2 antibody raised in participant sera was measured by means of an anti-Spike (S) IgG ELISA, and SARS-CoV-2 pseudoneutralisation assay. (The trial is registered: ISRCTN17072692, EudraCT 2020-001646-20). Findings: 216 healthy individuals (median age 51 years) received 1.0 μg followed by 10.0 μg of the vaccine. 28/216 participants were either known to have previous SARS-CoV2 infection and/or were positive for anti-Spike (S) IgG at baseline. Reactogenicity was as expected based on the reactions following licensed COVID-19 vaccines, and there were no serious AEs related to vaccination. 80% of baseline SARS-CoV-2 naïve individuals (147/183) seroconverted two weeks post second immunization, irrespective of age (18–75); 56% (102/183) had detectable neutralising antibodies. Almost all (28/31) SARS-CoV-2 positive individuals had increased S IgG binding antibodies following their first 1.0 μg dose with a ≥0.5log10 increase in 71% (22/31). Interpretation: Encapsulated saRNA was well tolerated and immunogenic in adults aged 18–75 years. Seroconversion rates in antigen naïve were higher than those reported in our dose-ranging study. Further work is required to determine if this difference is related to a longer dosing interval (14 vs. 4 weeks) or dosing with 1.0 μg followed by 10.0 μg. Boosting of S IgG antibodies was observed with a single 1.0 μg injection in those with pre-existing immune responses. Funding: Grants and gifts from the Medical Research Council UKRI (MC_PC_19076), the National Institute for Health Research/Vaccine Task Force, Partners of Citadel and Citadel Securities, Sir Joseph Hotung Charitable Settlement, Jon Moulton Charity Trust, Pierre Andurand, and Restore the Earth

COVAC1 phase 2a expanded safety and immunogenicity study of a self-amplifying RNA vaccine against SARS-CoV-2

Background: lipid nanoparticle (LNP) encapsulated self-amplifying RNA (saRNA) is well tolerated and immunogenic in SARS-CoV-2 seronegative and seropositive individuals aged 18–75. Methods: a phase 2a expanded safety and immunogenicity study of a saRNA SARS-CoV-2 vaccine candidate LNP-nCoVsaRNA, was conducted at participating centres in the UK between 10th August 2020 and 30th July 2021. Participants received 1 μg then 10 μg of LNP-nCoVsaRNA, ∼14 weeks apart. Solicited adverse events (AEs) were collected for one week post-each vaccine, and unsolicited AEs throughout. Binding and neutralisating antiSARS-CoV-2 antibody raised in participant sera was measured by means of an anti-Spike (S) IgG ELISA, and SARS-CoV-2 pseudoneutralisation assay. (The trial is registered: ISRCTN17072692, EudraCT 2020-001646-20). Findings: 216 healthy individuals (median age 51 years) received 1.0 μg followed by 10.0 μg of the vaccine. 28/216 participants were either known to have previous SARS-CoV2 infection and/or were positive for anti-Spike (S) IgG at baseline. Reactogenicity was as expected based on the reactions following licensed COVID-19 vaccines, and there were no serious AEs related to vaccination. 80% of baseline SARS-CoV-2 naïve individuals (147/183) seroconverted two weeks post second immunization, irrespective of age (18–75); 56% (102/183) had detectable neutralising antibodies. Almost all (28/31) SARS-CoV-2 positive individuals had increased S IgG binding antibodies following their first 1.0 μg dose with a ≥0.5log10 increase in 71% (22/31). Interpretation: encapsulated saRNA was well tolerated and immunogenic in adults aged 18–75 years. Seroconversion rates in antigen naïve were higher than those reported in our dose-ranging study. Further work is required to determine if this difference is related to a longer dosing interval (14 vs. 4 weeks) or dosing with 1.0 μg followed by 10.0 μg. Boosting of S IgG antibodies was observed with a single 1.0 μg injection in those with pre-existing immune responses.Funding: grants and gifts from the Medical Research Council UKRI (MC_PC_19076), the National Institute for Health Research/Vaccine Task Force, Partners of Citadel and Citadel Securities, Sir Joseph Hotung Charitable Settlement, Jon Moulton Charity Trust, Pierre Andurand, and Restore the Earth.</p