Efficacy and safety of respiratory syncytial virus prefusion F protein vaccine (RSVPreF3 OA) in older adults over 2 RSV seasons.

BACKGROUND: The adjuvanted RSV prefusion F protein-based vaccine (RSVPreF3 OA) was efficacious against RSV-related lower respiratory tract disease (RSV-LRTD) in ≥60-year-olds over 1 RSV season. We evaluated efficacy and safety of 1 RSVPreF3 OA dose and of 2 RSVPreF3 OA doses given 1 year apart against RSV-LRTD over 2 RSV seasons post-dose 1. METHODS: In this phase 3, blinded trial, ≥60-year-olds were randomized (1:1) to receive RSVPreF3 OA or placebo pre-season 1. RSVPreF3 OA recipients were re-randomized (1:1) to receive a second RSVPreF3 OA dose (RSV_revaccination group) or placebo (RSV_1dose group) pre-season 2; participants who received placebo pre-season 1 received placebo pre-season 2 (placebo group). Efficacy of both vaccine regimens against RSV-LRTD was evaluated over 2 seasons combined (confirmatory secondary objective, success criterion: lower limits of 2-sided confidence intervals [CIs] around efficacy estimates >20%). RESULTS: The efficacy analysis comprised 24,967 participants (RSV_1dose: 6227, RSV_revaccination: 6242, placebo: 12,498). Median efficacy follow-up was 17.8 months. Efficacy over 2 seasons of 1 RSVPreF3 OA dose was 67.2% (97.5% CI: 48.2-80.0) against RSV-LRTD and 78.8% (95% CI: 52.6-92.0) against severe RSV-LRTD. Efficacy over 2 seasons of a first dose followed by revaccination was 67.1% (97.5% CI: 48.1-80.0) against RSV-LRTD and 78.8% (95% CI: 52.5-92.0) against severe RSV-LRTD. Reactogenicity/safety of the revaccination dose were similar to dose 1. CONCLUSION: One RSVPreF3 OA dose was efficacious against RSV-LRTD over 2 RSV seasons in ≥60-year-olds. Revaccination 1 year post-dose 1 was well tolerated but did not seem to provide additional efficacy benefit in the overall study population. ClinicalTrials.gov registration: NCT04886596.

Safety and Immunogenicity of a Revaccination With a Respiratory Syncytial Virus Prefusion F Vaccine in Older Adults: A Phase 2b Study.

BACKGROUND: In the previous (parent) study, 2 doses of different formulations of an investigational vaccine against respiratory syncytial virus (RSVPreF3 OA) were well tolerated and immunogenic in older adults. This multicenter phase 2b extension study assessed safety and immunogenicity of a revaccination (third) dose of the 120 µg RSVPreF3-AS01E formulation. METHODS: In total, 122 older adults (60-80 years), previously vaccinated with 2 doses of RSVPreF3-AS01E formulations (containing 30, 60, or 120 µg RSVPreF3 antigen), received an additional 120 µg RSVPreF3-AS01E dose 18 months after dose 2. Vaccine safety was evaluated in all participants up to 6 months and immunogenicity in participants who received 120 µg RSVPreF3-AS01E doses until 1 month after dose 3. RESULTS: Similar to the parent study, mostly mild-to-moderate solicited adverse events and no vaccine-related serious adverse events or potential immune-mediated disorders were reported. Neutralizing titers and cell-mediated immune responses persisted for 18 months after 2-dose vaccination. Dose 3 increased RSV-specific neutralizing titers against RSV-A and RSV-B and median CD4+ T-cell frequencies. After dose 3, RSV-specific neutralizing titers but not CD4+ T-cell frequencies were below levels detected 1 month after dose 1. CONCLUSIONS: Revaccination with 120 µg RSVPreF3-AS01E 18 months after dose 2 is well tolerated and immunogenic in older adults. CLINICAL TRIALS REGISTRATION: NCT04657198; EudraCT, 2020-000692-21.

Respiratory syncytial virus (RSV) is a common, contagious seasonal virus causing respiratory tract infections. In older adults, RSV can cause serious respiratory illnesses or worsen underlying medical conditions such as chronic diseases of the lungs or heart failure. Severe disease may lead to hospitalization, increased need for oxygen, and ventilatory support. However, several vaccines against RSV in older adults have recently been licensed in the United States and European Union. This study evaluated safety and immune responses after revaccination (third dose) with an adjuvanted vaccine against RSV in older adults aged 60­80 years, who had received 2 doses of the vaccine with a similar adjuvanted formulation in a previous (parent) study. Revaccination was done with the licensed vaccine formulation, which was also selected for further investigation in several phase 3 clinical trials. This study found that immune responses against RSV persisted above prevaccination levels for at least 18 months after the second vaccination in the parent study. The third vaccine dose was well tolerated and recalled the immune responses in older adults. Together with the ongoing confirmatory clinical trials, these results help better characterize this RSV vaccine, in terms of safety and RSV-specific immune responses elicited in older adults.

Safety and immunogenicity of a respiratory syncytial virus prefusion F protein (RSVPreF3) candidate vaccine in older Japanese adults: A phase I, randomized, observer-blind clinical trial.

BACKGROUND: Respiratory syncytial virus (RSV) causes lower respiratory tract infection, with a high burden of disease among adults ≥60 years. This study assessed the safety, reactogenicity, and immunogenicity of an investigational adjuvanted RSV vaccine (RSVPreF3/AS01B) in Japanese adults aged 60-80 years. METHODS: Forty participants were randomized to receive two doses of RSVPreF3/AS01B or the placebo, in a 1:1 ratio, two months apart, in this placebo-controlled study. Solicited administration-site and systemic adverse events (AEs) were collected within 7 days and unsolicited AEs within 30 days post-vaccination. Serious AEs (SAEs) and potential immune-mediated diseases (pIMDs) were collected throughout the study (12 months post-dose 2). RSVPreF3-specific immunoglobulin G (IgG) antibody concentrations and neutralizing antibody (nAb) titers against RSV-A were evaluated on day (D)1, D31, D61, D91 and those against RSV-B on D1, D31, D91. RESULTS: Solicited AEs were reported more frequently in RSVPreF3/AS01B recipients (80.0%-90.0%) than in placebo recipients (10.0%-20.0%). Two RSVPreF3/AS01B recipients experienced grade 3 solicited AEs. Rate of unsolicited AEs were similar (30.0%-35.0%) in both groups. No RSVPreF3/AS01B recipient reported SAEs/pIMDs, while one placebo recipient reported two SAEs that were unrelated to vaccination. Baseline RSVPreF3-specific IgG and RSV-A/-B nAb levels were above the assay cut-off values. In the RSVPreF3/AS01B group, RSVPreF3-specific IgG concentrations increased 12.8-fold on D31 and 9.2-fold on D91 versus baseline while nAb titers increased 7.3-fold (RSV-A) and 8.4-fold (RSV-B) on D31 and 6.3-fold (RSV-A) and 9.9-fold (RSV-B) on D91. CONCLUSIONS: The RSVPreF3/AS01B vaccine was well tolerated and immunogenic in older Japanese adults. CLINICAL TRIAL REGISTRATION NUMBER: NCT04090658.

Safety and Immunogenicity of a Respiratory Syncytial Virus Prefusion F (RSVPreF3) Candidate Vaccine in Older Adults: Phase 1/2 Randomized Clinical Trial.

BACKGROUND: The aim of this study was to investigate safety and immunogenicity of vaccine formulations against respiratory syncytial virus (RSV) containing the stabilized prefusion conformation of RSV fusion protein (RSVPreF3). METHODS: This phase 1/2, randomized controlled, observer-blind study enrolled 48 young adults (YAs; aged 18-40 years) and 1005 older adults (OAs; aged 60-80 years) between January and August 2019. Participants were randomized into equally sized groups to receive 2 doses of unadjuvanted (YAs and OAs) or AS01-adjuvanted (OAs) vaccine or placebo 2 months apart. Vaccine safety and immunogenicity were assessed until 1 month (YAs) or 12 months (OAs) after second vaccination. RESULTS: The RSVPreF3 vaccines boosted humoral (RSVPreF3-specific immunoglobulin G [IgG] and RSV-A neutralizing antibody) responses, which increased in an antigen concentration-dependent manner and were highest after dose 1. Compared to prevaccination, the geometric mean frequencies of polyfunctional CD4+ T cells increased after each dose and were significantly higher in adjuvanted than unadjuvanted vaccinees. Postvaccination immune responses persisted until end of follow-up. Solicited adverse events were mostly mild to moderate and transient. Despite a higher observed reactogenicity of AS01-containing vaccines, no safety concerns were identified for any assessed formulation. CONCLUSIONS: Based on safety and immunogenicity profiles, the AS01E-adjuvanted vaccine containing 120 µg of RSVPreF3 was selected for further clinical development. CLINICAL TRIALS REGISTRATION: NCT03814590.

Reactogenicity, safety, and immunogenicity of chimeric haemagglutinin influenza split-virion vaccines, adjuvanted with AS01 or AS03 or non-adjuvanted: a phase 1-2 randomised controlled trial.

BACKGROUND: One strategy to develop a universal influenza virus vaccine is to redirect the immune system to the highly conserved haemagglutinin stalk domain by sequentially administering vaccines expressing chimeric (c) haemagglutinins with a conserved stalk domain and divergent head domain, to which humans are naive. We aimed to assess the reactogenicity, safety, and immunogenicity of adjuvanted and unadjuvanted investigational supra-seasonal universal influenza virus vaccines (SUIVs) in healthy young adults. METHODS: In this observer-masked, randomised, controlled, phase 1-2 trial, we recruited adults aged 18-39 years with no clinically significant conditions from six centres in Belgium and the USA. Participants were randomly assigned to ten equally sized groups via an online system with the MATerial Excellence programme. Vaccines contained heterosubtypic group 1 H8, H5, or H11 haemagglutinin heads, an H1 haemagglutinin stalk, and an N1 neuraminidase (cH8/1N1, cH5/1N1, and cH11/1N1; haemagglutinin dose 15 µg/0·5 mL), administered on days 1 and 57, with a month 14 booster. SUIVs were evaluated in the sequences: cH8/1N1-placebo-cH5/1N1, cH5/1N1-placebo-cH8/1N1, or cH8/1N1-cH5/1N1-cH11/1N1, adjuvanted with either AS03 or AS01, or not adjuvanted. The last group received inactivated quadrivalent influenza vaccine (IIV4)-placebo-IIV4. Primary outcomes were safety (analysed in the exposed population) and immunogenicity in terms of the anti-H1 stalk humoral response at 28 days after vaccination (analysed in the per-protocol population, defined as participants who received the study vaccines according to the protocol). This trial is registered with ClinicalTrials.gov, NCT03275389. FINDINGS: Between Sept 25, 2017, and March 26, 2020, 507 eligible participants were enrolled. 468 (92%) participants received at least one dose of study vaccine (exposed population), of whom 244 (52%) were included in the per-protocol population at final analysis at month 26. The safety profiles of all chimeric vaccines were clinically acceptable, with no safety concerns identified. Injection-site pain was the most common adverse event, occurring in 84-96% of participants receiving an adjuvanted SUIV or non-adjuvanted IIV4 and in 40-50% of participants receiving a non-adjuvanted SUIV. Spontaneously reported adverse events up to 28 days after vaccination occurred in 36-60% of participants, with no trends observed for any group. 17 participants had a serious adverse event, none of which were considered to be causally related to the vaccine. Anti-H1 stalk antibody titres were highest in AS03-adjuvanted groups, followed by AS01-adjuvanted and non-adjuvanted groups, and were higher after cH8/1N1 than after cH5/1N1 and after a two-dose primary schedule than after a one-dose schedule. Geometric mean concentrations by ELISA ranged from 21 938·1 ELISA units/mL (95% CI 18 037·8-26 681·8) in the IIV4-placebo-IIV4 group to 116 596·8 ELISA units/mL (93 869·6-144 826·6) in the AS03-adjuvanted cH8/1N1-cH5/1N1-cH11/1N1 group 28 days after the first dose and from 15 105·9 ELISA units/mL (12 007·7-19 003·6) in the non-adjuvanted cH5/1N1-placebo-cH8/1N1 group to 74 639·7 ELISA units/mL (59 986·3-92 872·6) in the AS03-adjuvanted cH8/1N1-cH5/1N1-cH11/1N1 group 28 days after the second dose. INTERPRETATION: The stalk domain seems to be a rational target for development of a universal influenza virus vaccine via administration of chimeric haemagglutinins with head domains to which humans are naive. FUNDING: GlaxoSmithKline Biologicals.

Safety profile of Infanrix hexa - 17 years of GSK's passive post-marketing surveillance.

INTRODUCTION: This paper reports 17 years of passive safety surveillance of routine use of the pediatric hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus-Haemophilus influenzae type b-conjugate vaccine (DTPa-HBV-IPV/Hib, Infanrix hexa, GSK). METHODS: Global post-licensure passive surveillance data collected in GSK's central safety database since DTPa-HBV-IPV/Hib's launch (2000) are described. RESULTS: The most common spontaneously reported adverse events (AEs) after DTPa-HBV-IPV/Hib vaccination in children were fever (reporting rate: 7.74/100,000 doses distributed), crying (2.62/100,000), injection site erythema (1.87/100,000) and swelling (1.28/100,000). A review of extensive limb swelling did not reveal any safety concerns. An observed-to-expected analysis did not show an increased risk of sudden death after DTPa-HBV-IPV/Hib vaccination, in line with previous observations. The analyses confirmed that increases in spontaneous reporting proportions of convulsions with/without fever and hypotonic-hyporesponsive episodes after co-administration of DTPa-HBV-IPV/Hib and 13-valent pneumococcal conjugate vaccine remained small and their clinical significance unknown. The most common vaccination errors were mistakes in the vaccination schedule. Reporting of preparation errors (mostly reconstitution) was low and did not impact the vaccine's benefit-risk profile. CONCLUSIONS: Seventeen years of post-licensure experience confirm confidence in the safety profile of DTPa-HBV-IPV/Hib in routine use, with a favorable benefit-risk profile in infants and toddlers. PLAIN LANGUAGE SUMMARY: What is the context? The cornerstone of childhood vaccination in many countries worldwide is a vaccine that protects against several diseases: diphtheria, tetanus, whooping cough, hepatitis B, polio and Haemophilus influenzae type b infections (such as meningitis). One of these vaccines (the longest on the market) is called Infanrix hexa; it has been available for infants and toddlers since 2000. After a vaccine is included in a country's routine vaccination program, its safety is constantly checked; this is done in clinical trials and through spontaneous reporting of adverse events after vaccination. It is important to share up-to-date information on the safety of vaccines, particularly since concerns about vaccine safety in parents may lead to lower vaccination rates an disease outbreaks. Here we summarize 17 years of safety data for the Infanrix hexa vaccine. What is new? We analyzed spontaneously reported adverse events after Infanrix hexa vaccinations between 2000 and 2017 The most commonly reported adverse events were fever, crying and injection site redness and swelling An in-depth review of extensive limb swelling after Infanrix hexa vaccination revealed no safety concerns. There was no increased risk of sudden death after Infanrix hexa vaccination, consistent with what was shown in several other studies. As shown previously, seizures were more common when Infanrix hexa was given together with the pneumococcal conjugate vaccine, Prevnar 13, than when it was given alone. What is the take-home message? The large amount of safety data gathered from clinical trials and from spontaneous adverse event reporting during 17 years of routine vaccination with Infanrix hexa supports its continued use in young children.

Biosafety aspects of modified vaccinia virus Ankara (MVA)-based vectors used for gene therapy or vaccination.

The modified vaccinia virus Ankara (MVA) strain is a highly attenuated strain of vaccinia virus that has been demonstrated to be safe for humans. MVA is widely considered as the vaccinia virus strain of choice for clinical investigation because of its high safety profile. It also represents an excellent candidate for use as vector system in recombinant vaccine development for gene delivery or vaccination against infectious diseases or tumours, even in immunocompromised individuals. The use of MVA and recombinant MVA vectors must comply with various regulatory requirements, particularly relating to the assessment of potential risks for human health and the environment. The purpose of the present paper is to highlight some biological characteristics of MVA and MVA-based recombinant vectors and to discuss these from a biosafety point of view in the context of the European regulatory framework for genetically modified organisms with emphasis on the assessment of potential risks associated with environmental release.

State-of-the-art lentiviral vectors for research use: risk assessment and biosafety recommendations.

Lentiviral vectors (LV) are competent gene transfer vehicles, as used for both research and gene therapy applications, because of their stable integration in non-dividing and dividing cells and long-term transgene expression. Along with our understanding that LV offer solutions for gene therapy, biosafety concerns have uncovered risks due to insertional mutagenesis, the generation of replication competent lentiviruses (RCL) and vector mobilization. Researchers therefore continue to devote significant efforts in designing LV with improved efficacy and biosafety features. The choice of a particular LV system for experimental studies is often driven by functional considerations, including increased productivity and/or transduction efficiency. The design of safer vectors has also directly benefited researchers allowing them to conduct experimental studies with lower risk. Currently, vectors combine improved safety features (that decrease the risk of recombination and vector mobilization) with increased transduction efficiency. Hence, risks associated with the inadvertent transduction of cells of the investigator gain greater importance in assessing the overall risk of these vectors and become an important biosafety concern. This review outlines the different strategies used to improve LV biosafety by comparing state-of-the-art and emerging LV production systems and highlighting biosafety issues that can arise during their contained use. The few existing national and international biosafety recommendations that specifically address the use of LV in research are discussed and recommendations for most common research activities using LV are proposed.

The incC korB region of RK2 repositions a mini-RK2 replicon in Escherichia coli.

Analysis by fluorescence microscopy has established that plasmid RK2 in Escherichia coli and other gram-negative bacteria is present as discrete clusters that are located inside the nucleoid at the mid- or quarter-cell positions. A mini-RK2 replicon containing an array of tetO repeats was visualized in E. coli cells that express a TetR-EYFP fusion protein. Unlike intact RK2, the RK2 mini-replicon (pCV1) was localized as a cluster at the cell poles outside of the nucleoid. Insertion of the O(B1)incC korB partitioning (par) region of RK2 into pCV1 resulted in a shift of the mini-replicon to within the nucleoid region at the mid- and quarter-cell positions. Despite the repositioning of the mini-RK2 replicon to the cellular positions where intact RK2 is normally located, the insertion of the intact O(B1) incC korB region did not significantly stabilize the mini-RK2 plasmid during cell growth. Deletions within the O(B1)incC or the korB region resulted in a failure of this par region to move pCV1 out of its polar position. The insertion of the par system of plasmid F into pCV1 resulted in a similar shift in the location of pCV1 to the nucleoid region. Unlike O(B1)incC korB, the insertion of the RK2 parABC resolvase system into pCV1 did not affect the polar positioning of pCV1. This effect of O(B1)incC korB on the location of pCV1 provides additional evidence for a partitioning role of this region of plasmid RK2. However, the failure of this region to significantly increase the stability of the mini-RK2 plasmid indicates that the localization of the plasmid to the mid- and quarter cell positions in E. coli is not in itself sufficient for the stable maintenance of plasmid RK2.

GIL16, a new gram-positive tectiviral phage related to the Bacillus thuringiensis GIL01 and the Bacillus cereus pBClin15 elements.

One of the most notable characteristics of Tectiviridae resides in their double-layer coats: the double-stranded DNA is located within a flexible lipoprotein vesicle covered by a rigid protein capsid. Despite their apparent rarity, tectiviruses have an extremely wide distribution compared to other phage groups. Members of this family have been found to infect gram-negative (PRD1 and relatives) as well as gram-positive (Bam35, GIL01, AP50, and phiNS11) hosts. Several reports have shown that tectiviruses infecting gram-negative bacteria are closely related, whereas no information is currently available on the genetic relationship among those infecting gram-positive bacteria. The present study reports the sequence of GIL16, a new isolate originating from Bacillus thuringiensis, and a genetic comparison of this isolate with the tectiviral bacteriophages Bam35 and GIL01, which originated from B. thuringiensis serovars Alesti and Israelensis, respectively. In contrast to PRD1 and its relatives, these are temperate bacteriophages existing as autonomous linear prophages within the host cell. Mutations in a particular motif in both the GIL01 and GIL16 phages are also shown to correlate with a switch to the lytic cycle. Interestingly, both bacterial viruses displayed narrow, yet slightly different, host spectrums. We also explore the hypothesis that pBClin15, a linear plasmid hosted by the Bacillus cereus reference strain ATCC 14579, is also a prophage. Sequencing of its inverted repeats at both extremities and a comparison with GIL01 and GIL16 emphasize its relationship to the Tectiviridae.

The Bacillus thuringiensis phage GIL01 encodes two enzymes with peptidoglycan hydrolase activity.

Bacteriophage GIL01, infecting Bacillus thuringiensis serovar israelensis, possesses a linear dsDNA genome of 14,931 bp with proteins attached to its 5' extremities and terminal inverted repeats at both ends. Viral particles are sensitive to organic solvents, suggesting that a lipid membrane is present in the capsid. All these characteristics are reminiscent of those found in members of the Tectiviridae family. Sequence analysis of GIL01 revealed the presence of two open reading frames (ORF25 and ORF30) encoding potential lytic enzymes, which were cloned and overexpressed in Escherichia coli. The muralytic activity of these two proteins, designated Mur1 and Mur2 respectively, was confirmed in situ using renaturing sodium dodecyl sulfate (SDS)-polyacrylamide gels containing bacterial cell wall preparations. While Mur2 degrading activity is limited to B. thuringiensis israelensis, Mur1 has a broader cleavage spectrum.

pGIL01, a linear tectiviral plasmid prophage originating from Bacillus thuringiensis serovar israelensis.

Bacillus thuringiensis serovar israelensis harbours, in addition to several circular plasmids, a small linear molecule of about 15 kb. Sequence analysis of this molecule, named pGIL01, showed the presence of at least 30 ORFs, five of which displayed similarity with proteins involved in phage systems: a B-type family DNA polymerase, a LexA-like repressor, two potential muramidases and a DNA-packaging protein (distantly related to the P9 protein of the tectiviral phage PRD1). Experimental evidence confirmed that pGIL01 indeed corresponds to the linear prophage of a temperate phage. This bacteriophage, named GIL01, produces small turbid plaques and is sensitive to organic solvents, which suggests the presence of lipid components in its capsid. Experiments using proteases and exonucleases also revealed that proteins are linked to the genomes of both pGIL01 prophage and GIL01 phage at their 5' extremities. Altogether, these features are reminiscent of those of phages found in the Tectiviridae family, and more specifically of those of PRD1, a broad-host-range phage of Gram-negative bacteria. Dot-blot hybridization, PFGE, PCR and RFLP analyses also showed the presence of pGIL01 variants in the Bacillus cereus group.