Antibody responses to crucial functional epitopes as a novel approach to assess immunogenicity of vaccine adjuvants

We are interested in developing a vaccine that prevents genital herpes. Adjuvants have a major impact on vaccine immunogenicity. We compared two adjuvants, an experimental Merck Sharp & Dohme lipid nanoparticle (LNP) adjuvant, LNP-2, with CpG oligonucleotide combined with alum for immunogenicity in mice when administered with herpes simplex virus type 2 (HSV-2) glycoproteins C, D and E (gC2, gD2, gE2). The immunogens are intended to produce neutralizing antibodies to gC2 and gD2, antibodies to gD2 and gE2 that block cell-to-cell spread, and antibodies to gE2 and gC2 that block immune evasion from antibody and complement, respectively. Overall, CpG/alum was better at producing serum and vaginal IgG binding antibodies, neutralizing antibodies, antibodies that block virus spread from cell-to-cell, and antibodies that block immune evasion domains on gC2. We used a novel high throughput biosensor assay to further assess differences in immunogenicity by mapping antibody responses to seven crucial epitopes on gD2 involved in virus entry or cell-to-cell spread. We found striking differences between CpG/alum and LNP-2. Mice immunized with gD2 CpG/alum produced higher titers of antibodies than LNP-2 to six of seven crucial epitopes and produced antibodies to more crucial epitopes than LNP-2. Measuring epitope-specific antibodies helped to define mechanisms by which CpG/alum outperformed LNP-2 and is a valuable technique to compare adjuvants.     

A study to evaluate the immunogenicity and shedding of live attenuated influenza vaccine strains in children 24–<48 months of age

BackgroundQuadrivalent live attenuated influenza vaccine (LAIV4) showed reduced effectiveness against the A/H1N1 component in the 2013–2014 and 2015–2016 influenza seasons. The most likely cause of reduced LAIV effectiveness against A(H1N1)pdm09 strains was poor intranasal replication.ObjectivesTo compare the immunogenicity and shedding of a new A/H1N1 strain (A/Slovenia), to a A/H1N1 strain known to have reduced effectiveness (A/Bolivia).Patients/methodsThis was a randomized, double-blind, multicenter study. Children aged 24–<48 months of age were randomized 1:1:1 to receive two doses of LAIV4 2017–2018 (LAIV4_A/Slovenia), or LAIV4 2015–2016 or trivalent LAIV (LAIV3) 2015–2016 formulations (LAIV4_A/Bolivia or LAIV3_A/Bolivia, respectively) on days 1 and 28. The primary endpoint was strain-specific hemagglutination inhibition (HAI) antibody seroresponse at 28 days post each dose, and secondary endpoints included immunogenicity, shedding, and safety. Solicited symptoms, adverse events (AEs), and serious AEs (SAEs) were recorded. Pre-specified statistical testing was limited to the primary endpoint of HAI antibody responses.ResultsA total of 200 children were randomized (median age 35.3 months; 53% male; 57% had previously received influenza vaccine). Significantly higher HAI antibody responses for the A/Slovenia strain were observed after Dose 1 and Dose 2. Neutralizing antibodies and nasal immunoglobulin A antibody responses were higher for A/Slovenia versus A/Bolivia. More children shed the A/Slovenia vaccine strain than the A/Bolivia strain on Days 4–7 after Dose 1. No deaths, SAEs, or discontinuations from vaccine occurred.ConclusionsThe new A(H1N1)pdm09 A/Slovenia LAIV strain demonstrated improved immunogenicity compared with a previous strain with reduced effectiveness and induced immune responses comparable to a highly efficacious pre-pandemic H1N1 LAIV strain. These results support the use of LAIV4 containing A/Slovenia as a vaccine option in clinical practice.     

Efficacy,safety and immunogenicity of a pneumococcal protein-based vaccine co-administered with 13-valent pneumococcal conjugate vaccine against acute otitis media in young children: A phase IIb randomized study

BackgroundNative American populations experience a substantial burden of pneumococcal disease despite use of highly effective pneumococcal conjugate vaccines (PCVs). Protein-based pneumococcal vaccines may extend protection beyond the serotype-specific protection elicited by PCVs.MethodsIn this phase IIb, double-blind, controlled trial, 6–12 weeks-old Native American infants randomized 1:1, received either a protein-based pneumococcal vaccine (dPly/PhtD) containing pneumolysin toxoid (dPly, 10 µg) and pneumococcal histidine triad protein D (PhtD, 10 µg) or placebo, administered along with 13-valent PCV (PCV13) at ages 2, 4, 6 and 12–15 months. Other pediatric vaccines were given per the routine immunization schedule. We assessed vaccine efficacy (VE) against acute otitis media (AOM) and acute lower respiratory tract infection (ALRI) endpoints. Immunogenicity, reactogenicity and unsolicited adverse events were assessed in a sub-cohort and serious adverse events were assessed in all children.Results1803 infants were randomized (900 dPly/PhtD; 903 Control). VE against all episodes of American Academy of Pediatrics (AAP)-defined AOM was 3.8% (95% confidence interval: −11.4, 16.9). Point estimates of VE against other AOM outcomes ranged between 2.9% (−9.5, 14.0) and 5.2% (−8.0, 16.8). Point estimates of VE against ALRI outcomes ranged between −4.4% (−39.2, 21.8) and 2.0% (−18.3, 18.8). Point estimates of VE tended to be higher against first than all episodes but the confidence intervals included zero. dPly/PhtD vaccine was immunogenic and had an acceptable reactogenicity and safety profile after primary and booster vaccination in Native American infants.ConclusionsThe dPly/PhtD vaccine was immunogenic and well tolerated, however, incremental efficacy in preventing AAP-AOM over PCV13 was not demonstrated.Clinical trials registrationNCT01545375 (www.clinicaltrials.gov)     

Safety and immunogenicity studies in animal models support clinical development of a bivalent norovirus-like particle vaccine produced in plants

Noroviruses (NoV) are the leading cause of epidemic acute gastroenteritis in humans worldwide. A safe and effective vaccine that prevents NoV infection or minimizes NoV disease burden is needed, especially for children and the elderly who are particularly susceptible to NoV disease. A plant-based expression system (magnICON®) was used to manufacture two different virus-like particle (VLP) immunogens derived from human NoV genogroups I and II, genotype 4 (GI.4 and GII.4), which were subsequently blended 1:1 (w/w) into a bivalent vaccine composition (rNV-2v). Here, we report on the safety and immunogenicity of rNV-2v from one pilot and two GLP-compliant toxicity studies in New Zealand White rabbits administered the vaccine subcutaneously (SC) or intramuscularly (IM). Strong genogroup-specific immune responses were induced by vaccination without adjuvant at various doses (200 to 400 μg VLP/administration) and administration schedules (Days 1 and 7; or Days 1, 15 and 29). The results showed sporadic local irritation at the injection site, which resolved over time, and was non-adverse and consistent with expected reactogenicity. There were no signs of systemic toxicity related to vaccine administration relative to vehicle-treated controls with respect to clinical chemistry, haematology, organ weights, macroscopic examinations, or histopathology. In a 3-administration regimen (n + 1 the clinical regimen), the NOAEL for rNV-2v via the SC or IM route was initially determined to be 200 μg. An improved GI.4 VLP variant mixed 1:1 (w/w) with the wild-type GII.4 VLP was subsequently evaluated via the IM route at a higher dose in the same 3-administration model, and the NOAEL was raised to 300 µg. Serology performed in samples of both toxicity studies showed significant and substantial anti-VLP-specific antibody titers for rNV-2v vaccines administered via the IM or SC route, as well as relevant NoV blocking antibody responses. These results support initiation of clinical development of the plant-made NoV vaccine.     

The adjuvanted recombinant zoster vaccine co-administered with a tetanus,diphtheria and pertussis vaccine in adults aged ≥50 years: A randomized trial

BackgroundThis study evaluated immunogenicity and safety of the adjuvanted recombinant zoster vaccine (RZV) and the reduced-antigen-content diphtheria-tetanus-acellular pertussis vaccine (Tdap) when co-administered in adults aged ≥50 years.MethodsIn this open label, multi-center study (NCT02052596), participants were randomized 1:1 to the Co-Administration group (RZV dose 1 and Tdap at Day 0 [D0], RZV dose 2 at Month 2 [M2]) or Control group (Tdap at D0, RZV dose 1 at M2, RZV dose 2 at M4). Co-primary objectives were evaluation of the vaccine response rate (VRR) to RZV in the Co-Administration group, and demonstration of non-inferiority of the humoral responses to RZV and Tdap in the Co-Administration compared to Control group. Reactogenicity and safety of RZV and Tdap were also assessed.ResultsVRR to RZV was 97.8% in the Co-Administration group. The non-inferiority criterion was met for the humoral response to RZV and for 4 Tdap antigens, but was not met for the Tdap antigen pertactin. Occurrences of solicited, unsolicited and serious adverse events, and potential immune-mediated diseases were similar between groups.ConclusionsCo-administration of RZV and Tdap did not interfere with the humoral immune response to RZV or 4 of the 5 Tdap antigens. No safety concerns were identified.     

Cellular and humoral immunity to Ebola Zaire glycoprotein and viral vector proteins following immunization with recombinant vesicular stomatitis virus-based Ebola vaccine (rVSVΔG-ZEBOV-GP)

While effective at preventing Zaire ebolavirus (ZEBOV) disease, cellular immunity to ZEBOV and vector-directed immunity elicited by the recombinant vesicular stomatitis virus expressing ZEBOV glycoprotein (rVSVΔG-ZEBOV-GP) vaccine remain poorly understood. Sera and peripheral blood mononuclear cells were collected from 32 participants enrolled in a prospective multicenter study [ClinicalTrials.gov NCT02788227] before vaccination and up to six months post-vaccination. IgM and IgG antibodies, IgG-producing memory B cells (MBCs), and T cell reactivity to ZEBOV glycoprotein (ZEBOV-GP), vesicular stomatitis virus-Indiana strain (VSV-I) matrix (M) protein, and VSV-I nucleoprotein (NP) were measured using ELISA, ELISpot, and flow cytometry, respectively. 11/32 (34.4%) participants previously received a different investigational ZEBOV vaccine prior to enrollment and 21/32 (65.6%) participants were ZEBOV vaccine naïve. Both ZEBOV vaccine naïve and experienced participants had increased ZEBOV-GP IgG optical densities (ODs) post-rVSVΔG-ZEBOV-GP vaccination while only ZEBOV vaccine naïve participants had increased ZEBOV-GP IgM ODs. Transient IgM and IgG antibody responses to VSV-I M protein and NP were observed in a minority of participants. All participants had detectable ZEBOV-GP specific IgG-producing MBCs by 6 months post-vaccination while no changes were observed in the median IgG-producing MBCs to VSV-I proteins. T cell responses to ZEBOV-GP differed between ZEBOV vaccine experienced and ZEBOV vaccine naïve participants. T cell responses to both VSV-I M protein and VSV-I NP were observed, but were of a low magnitude. The rVSVΔG-ZEBOV-GP vaccine elicits robust humoral and memory B cell responses to ZEBOV glycoprotein in both ZEBOV vaccine naïve and experienced individuals and can generate vector-directed T cell immunity. Further research is needed to understand the significance of pre-existing vector and target antigen immunity on responses to booster doses of rVSVΔG-ZEBOV-GP and other rVSV-vectored vaccines.     

Development and immunogenicity evaluation of porcine deltacoronavirus inactivated vaccine with different adjuvants in mice

Porcine deltacoronavirus (PDCoV) is a novel coronavirus that causes diarrhea in pigs of various ages, especially in suckling piglets, and there are no effective measures to prevent and control PDCoV currently. In this study, two adjuvants Al(OH)₃ and ODN2395 working through different mechanisms were used to prepare inactivated PDCoV vaccines, and the immune effects of PDCoV inactivated vaccines were assessed in mice. From the results, we found that both PDCoV/Al(OH)₃ vaccine and PDCoV/2395 vaccine could induce IgG and neutralizing antibodies with high levels in mice. At the same time, cytokines of IFN-γ, IL-4 and chemokine ligand of CXCL13 in serum were significantly increased after immunization, and reached the highest levels in PDCoV/2395 vaccine group, which suggested that PDCoV/2395 could promote the production of both Th1 and Th2 polarized cytokines. In addition, histopathological observations showed that vaccination helped mice resist PDCoV infection. These results indicated that both the two inactivated vaccines have good immune effects. Moreover, the PDCoV/2395 vaccine worked better than the PDCoV/Al(OH)₃ vaccine for PDCoV/2395 having the good ability to induce both humoral and cellular immunogenicity. The PDCoV/2395 inactivated vaccine developed in this study might be an effective tool for the prevention of PDCoV infection.     

Neutralizing antibody correlates of sequence specific dengue disease in a tetravalent dengue vaccine efficacy trial in Asia

In the CYD14 trial of the CYD-TDV dengue vaccine in 2–14 year-olds, neutralizing antibody (nAb) titers to the vaccine-insert dengue strains correlated inversely with symptomatic, virologically-confirmed dengue (VCD). Also, vaccine efficacy against VCD was higher against dengue prM/E amino acid sequences closer to the vaccine inserts. We integrated the nAb and sequence data types by assessing nAb titers as a correlate of sequence-specific VCD separately in the vaccine arm and in the placebo arm. In both vaccine and placebo recipients the correlation of nAb titer with sequence-specific VCD was stronger for dengue nAb contact site sequences closer to the vaccine (p = 0.005 and p = 0.012, respectively). The risk of VCD in vaccine (placebo) recipients was 6.7- (1.80)-fold lower at the 90th vs 10th percentile of nAb for viruses perfectly matched to CYD-TDV, compared to 2.1- (0.78)-fold lower at the 90th vs 10th percentile for viruses with five amino acid mismatches. The evidence for a stronger sequence-distance dependent correlate of risk for the vaccine arm indicates departure from the Prentice criteria for a valid sequence-distance specific surrogate endpoint and suggests that the nAb marker may affect dengue risk differently depending on whether nAbs arise from infection or also by vaccination. However, when restricting to baseline-seropositive 9–14 year-olds, the correlation pattern became more similar between the vaccine and placebo arms, supporting nAb titers as an approximate surrogate endpoint in this population. No sequence-specific nAb titer correlates of VCD were seen in baseline-seronegative participants. Integrated immune response/pathogen sequence data correlates analyses could help increase knowledge of correlates of risk and surrogate endpoints for other vaccines against genetically diverse pathogens.Trial registration: EU Clinical Trials Register 2014-001708-24; registration date 2014-05-26.     

A preliminary report of a randomized controlled phase 2 trial of the safety and immunogenicity of mRNA-1273 SARS-CoV-2 vaccine

BackgroundVaccines are urgently needed to prevent the global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We assessed the safety and immunogenicity of vaccine candidate mRNA-1273, encoding the prefusion-stabilized spike protein of SARS-CoV-2.MethodsThis phase 2, randomized, observer-blind, placebo-controlled trial was conducted at 8 sites in the USA, in healthy adults aged ≥18 years with no known history or risk of SARS-CoV-2 infection, and had not previously received an investigational CoV vaccine or treatment. Participants were stratified into two age cohorts (≥18-<55 and ≥55) and were randomly assigned (1:1:1) to either 50 or 100 µg of mRNA-1273, or placebo administered as two intramuscular injections 28 days apart. The primary outcomes were safety, reactogenicity, and immunogenicity assessed by anti-SARS-CoV-2-spike binding antibody level (bAb). Secondary outcome was immunogenicity assessed by SARS-CoV-2 neutralizing antibody (nAb) response.ResultsBetween 29 May and 8 July 2020, 600 participants were randomized, 300 per age cohort. The most common solicited adverse reactions were pain at injection site, headache, and fatigue following each vaccination in both age cohorts. One serious adverse event deemed unrelated by the site investigator occurred 33 days post-vaccination one. mRNA-1273 induced bAb and nAb by 28 days post-vaccination one that were higher at the 100 µg dose relative to the 50 µg dose; this difference was less apparent post-vaccination two. Binding antibodies and nAb increased substantially by 14 days following the second vaccination (day 43) to levels exceeding those of convalescent sera and remained elevated through day 57.ConclusionsVaccination with mRNA-1273 resulted in significant immune responses to SARS-CoV-2 in participants 18 years and older, with an acceptable safety profile, confirming the safety and immunogenicity of 50 and 100 µg mRNA-1273 given as a 2 dose-regimen.ClinicalTrials.gov; NCT04405076.     

Safety and immunogenicity of a quadrivalent seasonal influenza vaccine adjuvanted with hydroxypropyl-β-cyclodextrin: A phase 1 clinical trial

ObjectivesHydroxypropyl-β-cyclodextrin (HP-β-CyD), an oligosaccharide used as an excipient in pharmaceutical preparation, was recently reported to function as a vaccine adjuvant to co-administered antigens. In this study, we investigated the safety and immunogenicity of a seasonal influenza vaccine adjuvanted with HP-β-CyD (FluCyD-vac) in healthy adults compared with those of a standard seasonal influenza vaccine (Flu-vac).MethodsWe conducted a single-blinded randomized phase 1 clinical trial study, and used two quadrivalent split seasonal influenza vaccines: FluCyD-vac containing 9 μg of HA/strain and 20% w/v of HP-β-CyD, and Flu-vac containing 15 μg of hemagglutinin (HA)/strain only. All participants were randomly assigned to receive a single dose of Flu/CyD-vac or Flu-vac at a ratio of 2:1. We assessed solicited and unsolicited adverse events (AEs) and immune responses using hemagglutination inhibition (HI) titers. In addition, we assessed T-cell function in peripheral blood mononuclear cells (PBMCs), after stimulation with HA vaccine strains, using flow cytometry.ResultsAmong 36 healthy volunteers enrolled in the study (FluCyD-vac, n = 24; Flu-vac, n = 12), FluCyD-vac was well tolerated. Most of the solicited AEs were mild local skin reactions at the injection site. No serious AEs were reported in either group. HI titers 21 days after vaccination with FluCyD-vac were comparable with those of Flu-vac and sufficient to meet international criteria, despite reduced HA antigen doses. When PBMCs were stimulated with the four HA antigens in the vaccine, tumor necrosis factor (TNF)-α-producing CD4⁺ T cells were enhanced in the FluCyD-vac group.ConclusionFluCyD-vac was well-tolerated and immunogenic, despite containing 40% less HA antigens than Flu-vac. This study showed that HP-β-CyD is a potentially safe, novel adjuvant for human influenza vaccine.Clinical trial registry: UMIN000028530.     

Serostatus cutoff levels and fold increase to define seroresponse to recombinant vesicular stomatitis virus – Zaire Ebola virus envelope glycoprotein vaccine: An evidence-based analysis

The recombinant vesicular stomatitis virus – Zaire Ebola virus envelope glycoprotein (rVSVΔG-ZEBOV-GP) vaccine is a live recombinant vesicular stomatitis virus (VSV) where the VSV G protein is replaced with ZEBOV-GP. To better understand the immune response after receiving the rVSVΔG-ZEBOV-GP vaccine, the current analyses evaluated different definitions of seroresponse that differentiate vaccine and placebo recipients enrolled in a placebo-controlled clinical trial (PREVAIL; NCT02344407) in which a subset of the study participants had elevated baseline titers. Alternative values for serostatus cutoff (SSCO; 200–500 EU/mL) and/or fold rise (two- to five-fold) were applied to compare their ability to distinguish between participants receiving rVSVΔG-ZEBOV-GP or placebo. The results indicate that an SSCO of 200 EU/mL can be used to define seropositivity at baseline (i.e. pre-vaccination). The use of dual criteria of the same SSCO (200 EU/mL) together with a two-fold rise in antibody level from baseline provided the definition of seroresponse that maximized the statistical significance between vaccine recipients and placebo recipients post-vaccination.Clinical trial registration: NCT02344407.     

Safety and immunogenicity of Multimeric-001 (M-001) followed by seasonal quadrivalent inactivated influenza vaccine in young adults – A randomized clinical trial

BackgroundThe continuing evolution of influenza viruses poses a challenge to vaccine prevention, highlighting the need for a universal influenza vaccine. We evaluated the safety and immunogenicity of one such candidate, Multimeric-001 (M-001), when used as a priming vaccine prior to administration of quadrivalent inactivated influenza vaccine (IIV4).MethodsHealthy adults 18 to 49 years of age were enrolled in a phase 2 randomized, double-blind placebo-controlled trial. Participants received two doses of either 1.0-mg M-001 or saline placebo (60 per study arm) on Days 1 and 22 followed by a single dose of IIV4 on about Day 172. Safety, reactogenicity, cellular immune responses and influenza hemagglutination inhibition (HAI) and microneutralization (MN) were assessed.ResultsThe M-001 vaccine was safe and had an acceptable reactogenicity profile. Injection site tenderness (39% post-dose 1, 29% post-dose 2) was the most common reaction after M-001 administration. Polyfunctional CD4+ T cell responses (perforin-negative, CD107α-negative, TNF-α+, IFN-γ+, with or without IL-2) to the pool of M-001 peptides increased significantly from baseline to two weeks after the second dose of M-001, and this increase persisted through Day 172. However, there was no enhancement of HAI or MN antibody responses among M-001 recipients following IIV4 administration.ConclusionsM-001 administration induced a subset of polyfunctional CD4+ T cells that persisted through 6 months of follow-up, but it did not improve HAI or MN antibody responses to IIV4. (clinicaltrials.gov NCT03058692).     

A randomized phase 3 trial of the immunogenicity and safety of coadministration of a live-attenuated tetravalent dengue vaccine (TAK-003) and an inactivated hepatitis a (HAV) virus vaccine in a dengue non-endemic country

BackgroundVaccination against hepatitis A virus (HAV) is largely recommended for travelers worldwide. Concurrent dengue and HAV vaccination may be desired in parallel for travelers to countries where both diseases are endemic. This randomized, observer-blind, phase 3 trial evaluated coadministration of HAV vaccine with tetravalent dengue vaccine (TAK-003) in healthy adults aged 18–60 years living in the UK.MethodsParticipants were randomized (1:1:1) to receive HAV vaccine and placebo on Day 1, and placebo on Day 90 (Group 1), TAK-003 and placebo on Day 1, and TAK-003 on Day 90 (Group 2), or TAK-003 and HAV vaccine on Day 1, and TAK-003 on Day 90 (Group 3). The primary objective was non-inferiority of HAV seroprotection rate (anti-HAV ≥ 12.5 mIU/mL) in Group 3 versus Group 1, one month post-first vaccination (Day 30) in HAV-naïve and dengue-naïve participants. Sensitivity analyses were performed on combinations of baseline HAV and dengue serostatus. Secondary objectives included dengue seropositivity one month post-second vaccination (Day 120), HAV geometric mean concentrations (GMCs), and safety.Results900 participants were randomized. On Day 30, HAV seroprotection rates were non-inferior following coadministration of HAV and TAK-003 (Group 3: 98.7 %) to HAV administration alone (Group 1: 97.1 %; difference: ?1.68, 95 % CI: ?8.91 to 4.28). Sensitivity analyses including participants who were neither HAV-naïve nor DENV-naïve at baseline supported this finding. Anti-HAV GMCs on Day 30 were 82.1 (95 % CI: 62.9–107.1) mIU/mL in Group 1 and 93.0 (76.1–113.6) mIU/mL in Group 3. By Day 120, 90.9–96.8 % of TAK-003 recipients were seropositive (neutralizing antibody titer > 10) to all four dengue serotypes. Coadministration of HAV vaccine and TAK-003 was well tolerated, with no important safety risks identified.ConclusionImmune responses following coadministration of HAV vaccine and TAK-003 were non-inferior to administration of HAV vaccine alone. The results support the coadministration of HAV vaccine and TAK-003 with no adverse impact on immunogenicity, safety, and reactogenicity of either vaccine.ClinicalTrials.gov registration: NCT03525119.     

A phase 1, randomized,placebo-controlled,dose-ranging study to evaluate the safety and immunogenicity of an mRNA-based chikungunya virus vaccine in healthy adults

BackgroundChikungunya, a mosquito-borne viral disease caused by the chikungunya virus (CHIKV), causes a significant global health burden, and there is currently no approved vaccine to prevent chikungunya disease. In this study, the safety and immunogenicity of a CHIKV mRNA vaccine candidate (mRNA-1388) were evaluated in healthy participants in a CHIKV-nonendemic region.MethodsThis phase 1, first-in-human, randomized, placebo-controlled, dose-ranging study enrolled healthy adults (ages 18–49 years) between July 2017 and March 2019 in the United States. Participants were randomly assigned (3:1) to receive 2 intramuscular injections 28 days apart with mRNA-1388 in 3 dose-level groups (25 μg, 50 μg, and 100 μg) or placebo and were followed for up to 1 year. Safety (unsolicited adverse events [AEs]), tolerability (local and systemic reactogenicity; solicited AEs), and immunogenicity (geometric mean titers [GMTs] of CHIKV neutralizing and binding antibodies) of mRNA-1388 versus placebo were evaluated.ResultsSixty participants were randomized and received ≥ 1 vaccination; 54 (90 %) completed the study. mRNA-1388 demonstrated favorable safety and reactogenicity profiles at all dose levels. Immunization with mRNA-1388 induced substantial and persistent humoral responses. Dose-dependent increases in neutralizing antibody titers were observed; GMTs (95 % confidence intervals [CIs]) at 28 days after dose 2 were 6.2 (5.1–7.6) for mRNA-1388 25 μg, 53.8 (26.8–108.1) for mRNA-1388 50 μg, 92.8 (43.6–197.6) for mRNA-1388 100 μg, and 5.0 (not estimable) for placebo. Persistent humoral responses were observed up to 1 year after vaccination and remained higher than placebo in the 2 higher mRNA-1388 dose groups. The development of CHIKV-binding antibodies followed a similar trend as that observed with neutralizing antibodies.ConclusionsmRNA-1388, the first mRNA vaccine against CHIKV, was well tolerated and elicited substantial and long-lasting neutralizing antibody responses in healthy adult participants in a nonendemic region.ClinicalTrials.gov: NCT03325075.     

A simple and rapid assay to evaluate purity of foot-and-mouth disease vaccine before animal experimentation

Currently, foot-and-mouth disease (FMD) vaccine purity is tested in cattle to detect antibodies against the non-structural protein (NSP) after repeated immunization with the final vaccine product. In case of vaccine failure, the manufacturing company would suffer significant economic loss. To prevent such unfortunate losses with the final vaccine product, in vitro testing is required to quantitate an NSP antigen during the manufacturing process prior to animal experiments. A novel lateral-flow assay device was developed using a monoclonal antibody (MAb) against the 3B NSP. To determine the minimal amount of NSP required to elicit antibodies in livestock, goats were immunized several times with various concentrations of either the recombinant 3AB (rec.3AB) protein or FMD virus culture supernatant. Antibodies against 3AB were elicited after a second immunization with 10.6 ng to 42.5 ng of rec.3AB and a third immunization with a 10-fold diluted FMD virus culture supernatant in goats. The lateral-flow assay device detected the minimal amount of rec.3AB and native NSP in FMD virus culture supernatant required to induce NSP antibodies in goats. The in vitro assay device is simple and economical, provides rapid results, and should be useful for FMD vaccine-manufacturing companies prior to conducting animal experiments to test the vaccine purity.     

A phase 1 antigen dose escalation trial to evaluate safety,tolerability and immunogenicity of the leprosy vaccine candidate LepVax (LEP-F1 + GLA–SE) in healthy adults

Healthy United States-based adult volunteers with no history of travel to leprosy-endemic countries were enrolled for the first-in-human evaluation of LepVax (LEP-F1 + GLA-SE). In total 24 volunteers participated in an open-label clinical trial, with 21 receiving three injections of LepVax consisting of either 2 µg or 10 µg recombinant polyprotein LEP-F1 mixed with 5 µg of the GLA-SE adjuvant formulation. LepVax doses were provided by intramuscular injection on Days 0, 28, and 56, and safety was evaluated for one year following the final injection. LepVax was safe and well tolerated at both antigen doses. Immunological analyses indicated that similar LEP-F1-specific antibody and Th1 cytokine secretion (IFN-γ, IL-2, TNF) were induced by each of the antigen doses evaluated within LepVax. This clinical trial of the first defined vaccine candidate for leprosy demonstrates that LepVax is safe and immunogenic in healthy subjects and supports its advancement to testing in leprosy-endemic regions.     

Safety and immunogenicity of 15-valent pneumococcal conjugate vaccine in Japanese healthy infants: A phase III study (V114-033)

BackgroundThis phase III study evaluated safety, tolerability, and immunogenicity of V114 (15-valent pneumococcal conjugate vaccine) in Japanese infants. V114 contains all 13 serotypes in PCV13 plus additional serotypes 22F and 33F.MethodsHealthy Japanese infants were randomized to receive three primary doses of V114 or PCV13 (dose 1 at 2–6 months of age; doses 2 and 3 ≥ 27 days after prior dose), plus a toddler dose at 12–15 months of age. Adverse events (AEs) were collected on Days 1–14 following each vaccination. Serotype-specific anti-pneumococcal immunoglobulin G (IgG) was measured 30 days post-dose 3, pre-dose 4, and 30 days post-dose 4. Primary objectives included non-inferiority of V114 to PCV13 for the 13 shared serotypes based on serotype-specific IgG response rates (IgG ≥ 0.35 μg/mL) and geometric mean concentration (GMC) ratios, and for serotypes 22F and 33F based on IgG response rates and compared with the lowest response of any serotype in the PCV13 group, at 30 days post-dose 3.ResultsOverall, 694 infants were randomized to V114 (n = 347) or PCV13 (n = 347). Proportions of participants with solicited and serious AEs were comparable between vaccination groups. V114 met non-inferiority criteria for all 13 shared serotypes, based on difference in proportion of responders (lower bound of two-sided 95 % confidence interval [CI] > −10.0) and IgG GMC ratios (V114/PCV13, lower bound of two-sided 95 % CI > 0.5) at 30 days post-dose 3. The non-inferiority criterion based on IgG response rates was met for serotype 22F, but narrowly missed for serotype 33F (90.9 %, lower bound of two-sided 95 % CI −10.6).ConclusionIn Japanese infants, a four-dose series of V114 was generally well tolerated. Compared with PCV13, V114 provided non-inferior immune responses to the 13 shared serotypes and higher immune responses to serotype 22F and 33F post-primary series.Trial registration: ClinicalTrials.gov: NCT04384107; EudraCT 2019-003644-68.     

Effectiveness of recombinant zoster vaccine (RZV) in patients with inflammatory bowel disease

Background and AimsPatients with Inflammatory bowel disease (IBD) are at an increased risk of developing herpes zoster (HZ). The effectiveness of the recombinant zoster vaccine (RZV) in patients with IBD is unknown.MethodsIn this retrospective cohort study using Explorys (October 2017–April 2020; IBM Corporation, Somers, NY, USA), the effectiveness of RZV for the prevention of HZ in patients with IBD ≥ 50 years was compared to general population aged ≥ 50 years. Rates of de-novo HZ were compared between patients with IBD and the general population and stratified by number of RZV doses received. Results are presented as odds ratios (OR) with 95% confidence intervals (CI).ResultsThe overall proportion of IBD patients ≥ 50 years who received HZ vaccination with the live zoster vaccine (ZVL) or RZV was low (n = 11320, out of 112,200 IBD patients in the cohort). A total of 1670 patients received RZV. Receipt of the RZV resulted in a significantly lower rate of HZ in IBD patients (OR 0.36, 95% CI 0.23–0.56) compared to the general population (OR 0.74, 95% CI 0.59–0.92). However, despite vaccination, patients with IBD who received the RZV were still 3-times more likely to develop HZ during the study follow up period compared to the general population receiving the RZV (OR 3.06, 95% CI 1.87–5.02) and unvaccinated IBD patients were 6-times more likely to develop HZ compared to general population (OR 6.21, 95% CI 6.02–6.41).ConclusionThe recombinant zoster vaccine is effective in reducing the risk of HZ in patients with IBD compared to the general population. During our follow up period, patients with IBD, however, still remain at an increased risk for HZ despite vaccination.