No immunological interference or concerns about safety when seasonal quadrivalent influenza vaccine is co-administered with a COVID-19 mRNA-1273 booster vaccine in adults: A randomized trial

The objective of the study was to assess the safety and immunogenicity of mRNA-1273 COVID-19 booster vaccination when co-administered with an egg-based standard dose seasonal quadrivalent influenza vaccine (QIV). This was a phase 3, randomized, open-label study. Eligible adults aged ≥ 18 years were randomly assigned (1:1) to receive mRNA-1273 (50 µg) booster vaccination and QIV 2 weeks apart (Seq group) or concomitantly (Coad group). Primary objectives were non-inferiority of haemagglutinin inhibition (HI) and anti-Spike protein antibody responses in the Coad compared to Seq group. 497/498 participants were randomized and vaccinated in the Seq/Coad groups, respectively. The adjusted geometric mean titer/concentration ratios (95% confidence intervals) (Seq/Coad) for HI antibodies were 1.02 (0.89-1.18) for A/H1N1, 0.93 (0.82-1.05) for A/H3N2, 1.00 (0.89-1.14] for B/Victoria, and 1.04 (0.93-1.17) for B/Yamagata; and 0.98 (0.84-1.13) for anti-Spike antibodies, thus meeting the protocol-specified non-inferiority criteria. The most frequently reported adverse events in both groups were pain at the injection site and myalgia. The 2 groups were similar in terms of the overall frequency, intensity, and duration of adverse events. In conclusion, co-administration of mRNA-1273 booster vaccine with QIV in adults was immunologically non-inferior to sequential administration. Safety and reactogenicity profiles were similar in both groups (clinicaltrials.gov NCT05047770).

A phase 3 randomized, open-label study evaluating the immunogenicity and safety of concomitant and staggered administration of a live, pentavalent rotavirus vaccine and an inactivated poliomyelitis vaccine in healthy infants in China

This open-label, randomized, phase 3 study in China (V260-074; NCT04481191) evaluated the immunogenicity and safety of concomitant and staggered administration of three doses of an oral, live, pentavalent rotavirus vaccine (RV5) and three doses of an intramuscular, inactivated poliomyelitis vaccine (IPV) in 400 healthy infants. The primary objective was the non-inferiority of neutralizing antibody (nAb) responses in the concomitant- versus the staggered-use groups. Antibody responses were measured at baseline and 1-month post-dose 3 (PD3). Parents/legal guardians recorded adverse events for 30 or 15 d after study vaccinations in the concomitant-use or staggered-use groups, respectively. At PD3, >98% of participants seroconverted to all three poliovirus types, and the primary objective was met as lower bounds of the two-sided 95% CI for between-group difference in nAb seroconversion percentages ranged from - 4.3% to - 1.6%, for all poliovirus types, p < .001. At PD3, geometric mean titers (GMTs) of nAb responses to poliovirus types 1, 2, and 3 in the concomitant-use group and the staggered-use group were comparable; 100% of participants had nAb titers ≥1:8 and ≥1:64 for all poliovirus types. Anti-rotavirus serotype-specific IgA GMTs and participants with ≥3-fold rise in postvaccination titers from baseline were comparable between groups. Administration of RV5 and IPV was well tolerated with comparable safety profiles in both groups. The immunogenicity of IPV in the concomitant-use group was non-inferior to the staggered-use group and RV5 was immunogenic in both groups. No safety concerns were identified. These data support the concomitant use of RV5 and IPV in healthy Chinese infants.

Lot-to-lot consistency, immunogenicity, and safety of the Ad26.ZEBOV, MVA-BN-Filo Ebola virus vaccine regimen: A phase 3, randomized, double-blind, placebo-controlled trial

This phase-3, double-blind, placebo-controlled study (NCT04228783) evaluated lot-to-lot consistency of the Ad26.ZEBOV, MVA-BN-Filo Ebola vaccine regimen. Participants were randomized (6:6:6:1) to receive the two-dose regimen from three consecutively manufactured lots of Ad26.ZEBOV on Day 1 paired with three consecutively manufactured lots of MVA-BN-Filo on Day 57 (Groups 1-3) or two doses of placebo (Group 4). An additional cohort also received an Ad26.ZEBOV booster or placebo 4 months post-dose 2. Equivalence of the immunogenicity at 21 days post-dose 2 between any two groups was demonstrated if the 95% confidence interval (CI) of the Ebola virus glycoprotein (EBOV GP)-binding antibody geometric mean concentration (GMC) ratio was entirely within the prespecified margin of 0.5-2.0. Lot-to-lot consistency (i.e., consecutive lots can be consistently manufactured) was accomplished if equivalence was shown for all three pairwise comparisons. Results showed that the primary objective in the per-protocol immunogenicity subset (n = 549) was established for each pairwise comparison (Group 1 vs 2: GMC ratio = 0.9 [95% CI: 0.8, 1.1], Group 1 vs 3: 0.9 [0.8, 1.1], Group 2 vs 3: 1.0 [0.9, 1.2]). Equivalence of the three groups for the Ad26.ZEBOV component only was also demonstrated at 56 days post-dose 1. EBOV GP-binding antibody responses (post-vaccination concentrations >2.5-fold from baseline) were observed in 419/421 (99.5%) vaccine recipients at 21 days post-dose 2 and 445/460 (96.7%) at 56 days post-dose 1. In the booster cohort (n = 39), GMCs increased 9.0- and 11.8-fold at 7 and 21 days post-booster, respectively, versus pre-booster. Ad26.ZEBOV, MVA-BN-Filo was well tolerated, and no safety issues were identified.

Immunogenicity and safety of concomitant administration of recombinant COVID-19 vaccine and quadrivalent inactivated influenza vaccine in Chinese adults: An open-label, randomized, controlled trial

The immunogenicity and safety of the concomitant administration of recombinant COVID-19 vaccine and quadrivalent inactivated influenza vaccine (Split Virion) (QIIV) in Chinese adults are unclear. In this open-label, randomized controlled trial, participants aged ≥ 18 years were recruited. Eligible healthy adults were randomly assigned (1:1) to receive QIIV at the same time as the first dose of COVID-19 vaccine (simultaneous-group) or 14 days after the second dose of COVID-19 vaccine (non-simultaneous-group). The primary outcome was to compare the difference in immunogenicity of QIIV (H1N1, H3N2, Yamagata, and Victoria) between the two groups. A total of 299 participants were enrolled, 149 in the simultaneous-group and 150 in the non-simultaneous-group. There were no significant differences in geometric mean titer (GMT) [H1N1: 386.4 (95%CI: 299.2-499.0) vs. 497.4 (95%CI: 377.5-655.3); H3N2: 66.9 (95%CI: 56.1-79.8) vs. 81.4 (95%CI: 67.9-97.5); Yamagata: 95.6 (95%CI: 79.0-115.8) vs. 74.3 (95%CI: 58.6-94.0); and Victoria: 48.5 (95%CI: 37.6-62.6) vs. 65.8 (95%CI: 49.0-88.4)] and seroconversion rate (H1N1: 87.5% vs. 90.1%; H3N2: 58.1% vs. 62.0%; Yamagata: 75.0% vs. 64.5%; and Victoria: 55.1% vs. 62.8%) of QIIV antibodies between the simultaneous and non-simultaneous groups. For the seroprotection rate of QIIV antibodies, a higher seroprotection rate of Yamagata antibody was observed only in the simultaneous-group than in the non-simultaneous-group [86.0% vs. 76.0%, p = .040]. In addition, no significant difference in adverse events was observed between the two groups (14.2% vs. 23.5%, p = .053). In conclusion, no immune interference or safety concerns were found for concomitant administration of COVID-19 vaccine with QIIV in adults aged ≥ 18 years.

Immunogenicity and safety of live attenuated and recombinant/inactivated varicella zoster vaccines in people living with HIV: A systematic review

Few papers focus their attention on VZV vaccination effectiveness among people living with HIV (PLWH). Flanking the live attenuated vaccine (VZL) available, a newly recombinant vaccine (RZV) was recently introduced and approved for HZ prevention among adults. PLWH represents a population on which a particular attention should be applied, in order to guarantee the vaccine efficacy and safety. We performed a literature search in USNLM, PubMed, PubMed Central, PMC and Cochrane Library. From all the publications found eligible, data were extracted and processed per population, vaccine type, immunogenicity and ADRs. The review of the 13 included studies shows that both RZV and VZL are immunogenic and have an acceptable safety profile in adults and children living with HIV. However, given the lack of research available about vaccine efficacy in preventing VZV and HZ in PLWH, additional studies need to be performed, in order to achieve a full completeness of data.

A phase 4, open-label study to evaluate the safety and immunogenicity of DTaP5-HBV-IPV-Hib in children previously vaccinated with DTaP2-HBV-IPV-Hib or DTaP5-HBV-IPV-Hib (V419-016)

DTaP5-HBV-IPV-Hib (Vaxelis®) is a hexavalent combination vaccine (HV) indicated in infants and toddlers for the prevention of diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis, and invasive disease due to Haemophilus influenzae type b. Switching between HVs during the childhood vaccination series is sometimes necessary due to, for example, vaccine availability, health-care provider preference, and/or tender awards. The purpose of this study was to describe the safety, tolerability, and immunogenicity of a booster dose of Vaxelis® in participants who previously received a primary infant series of either DTaP2-HBV-IPV-Hib (Hexyon®) or Vaxelis®. Healthy participants approximately 11-13 months of age who previously received a two-dose primary series of Hexyon® (HHV group) or Vaxelis® (VVV group) all received a Vaxelis® booster dose. Immunogenicity was evaluated by measuring antibody levels to individual vaccine antigens approximately 30 days following booster vaccination. Safety was evaluated as the proportion of participants with adverse events (AEs). The proportions of participants with antibody-specific responses for antigens contained in both Vaxelis® and Hexyon® at 30 days post-toddler-booster vaccination with Vaxelis® were comparable between groups, and higher in the VVV group for Vaxelis® antigens PRN and FIM2/3. The overall proportions of participants with AEs were generally comparable between groups. Following a booster dose of Vaxelis®, immune responses were comparable between groups for all shared antigens, and higher in the VVV group for antigens found only in Vaxelis®. The booster was well tolerated in both groups. These data support the use of Vaxelis® as a booster in mixed HV regimens.

Seropersistence of SII-ChAdOx1 nCoV-19 (COVID-19 vaccine): 6-month follow-up of a randomized, controlled, observer-blind, phase 2/3 immuno-bridging study in Indian adults

AZD1222 (ChAdOx1 nCoV-19) is a replication-deficient adenoviral vectored coronavirus disease-19 (COVID-19) vaccine that is manufactured as SII-ChAdOx1 nCoV-19 by the Serum Institute of India Pvt Ltd following technology transfer from Oxford University/AstraZeneca. The non-inferiority of SII-ChAdOx1 nCoV-19 with AZD1222 was previously demonstrated in an observer-blind, phase 2/3 immuno-bridging study (trial registration: CTRI/2020/08/027170). In this analysis of immunogenicity and safety data 6 months post first vaccination (Day 180), 1,601 participants were randomized 3:1 to SII-ChAdOx1 nCoV-19 or AZD1222 (immunogenicity/reactogenicity cohort n = 401) and 3:1 to SII-ChAdOx1 nCoV-19 or placebo (safety cohort n = 1,200). Immunogenicity was measured by anti-severe acute respiratory syndrome coronavirus 2 spike (anti-S) binding immunoglobulin G and neutralizing antibody (nAb) titers. A decline in anti-S titers was observed in both vaccine groups, albeit with a greater decline in SII-ChAdOx1 nCoV-19 vaccinees (geometric mean titer [GMT] ratio [95% confidence interval (CI) of SII-ChAdOx1 nCoV-19 to AZD1222]: 0.60 [0.41-0.87]). Consistent similar decreases in nAb titers were observed between vaccine groups (GMT ratio [95% CI]: 0.88 [0.44-1.73]). No cases of severe COVID-19 were reported following vaccination, while one case was observed in the placebo group. No causally related serious adverse events were reported through 180 days. No thromboembolic or autoimmune adverse events of special interest were reported. Collectively, these data illustrate that SII-ChAdOx1 nCoV-19 maintained a high level of immunogenicity 6 months post-vaccination. SII-ChAdOx1 nCoV-19 was safe and well tolerated.

Investigation of pharmacokinetics and immunogenicity of magnetosomes

Magnetosomes are iron oxide or iron sulphide nano-sized particles surrounded by a lipid bilayer synthesised by a group of bacteria known as magnetotactic bacteria (MTB). Magnetosomes have become a promising candidate for biomedical applications and could be potentially used as a drug-carrier. However, pharmacokinetics and immunogenicity of the magnetosomes have not been understood yet which preclude its clinical applications. Herein, we investigated the pharmacokinetics of magnetosomes including Absorption, Distribution, Metabolism, and Elimination (ADME) along with its immunogenicity in vitro and in vivo. The magnetosomes were conjugated with fluorescein isothiocyanate (Mag-FITC) and their conjugation was confirmed through fluorescence microscopy and its absorption in HeLa cell lines was evaluated using flow cytometry analysis. The results revealed a maximum cell uptake of 97% at 200 µg/mL concentration. Further, the biodistribution of Mag-FITC was investigated in vivo by a bioimaging system using BALB/c mice as a subject at different time intervals. The Mag-FITC neither induced death nor physical distress and the same was eliminated post 36 h of injection with meagre intensities left behind. The metabolism and elimination analysis were assessed to detect the iron overload which revealed that magnetosomes were entirely metabolised within 48-h interval. Furthermore, the histopathology and serum analysis reveal no histological damage with the absence of any abnormal biochemical parameters. The results support our study that magnetosomes were completely removed from the blood circulation within 48-h time interval. Moreover, the immunogenicity analysis has shown that magnetosomes do not induce any inflammation as indicated by reduced peaks of immune markers such as IL 1β, IL 2, IL 6, IL8, IFN γ, and TNF α estimated through Indirect ELISA. The normal behaviour of animals with the absence of acute or chronic toxicities in any organs declares that magnetosomes are safe to be injected. This shows that magnetosomes are benign for biological systems enrouting towards beneficial biomedical applications. Therefore, this study will advance the understanding and application of magnetosomes for clinical purposes.

Safety and immunogenicity of CoronaVac in healthy adults: A prospective observational multicenter real-world study in Henan Province, China

Vaccination has emerged as the primar approach for managing the COVID-19 pandemic. Despite certain clinical trials reporting the safety and immunogenicity of CoronaVac, additional multicenter real-world studies are still necessary. In this study, we recruited 506 healthy volunteers who were not infected with COVID-19 or vaccinated. Each participant provided peripheral blood samples three times: prior to the first dose of vaccine, prior to the second dose, and 8 weeks following the second dose. Ultimately, 388 participants completed the entire follow-up process. No serious adverse events were observed among any of the participants. Within 1 week of vaccination, 13.4% of participants experienced systemic adverse reactions, with fatigue (5.93%) and dizziness (3.35%) being the most frequent. Although some clinical indicators, including creatinine, significantly changed after vaccination (p < 0.05), the mean of all altered indicators remained within the normal range. The positive rates of neutralizing antibodies (NAb), IgG, and IgM were 12.3%, 18.85%, and 5.24% prior to the second dose, respectively; and 57.99%, 86.34%, and 2.32% at 8 weeks following the second dose, respectively. Additionally, seven indicators, such as sex, age, and BMI, were significantly correlated with NAb (p < 0.05). Finally, a prediction model was developed based on age, monocytes, and alanine aminotransferase (ALT) with an AUC value of 87.56% in the train set and 80.71% in the test set. This study demonstrated that safety and immunogenicity of CoronaVac were good. The prediction model based on the baseline clinical characteristics prior to vaccination can help to develop more suitable vaccination strategies.

Efficacy and immunogenicity of AS04-HPV-16/18 vaccine in females with existing cervical HR-HPV infection at first vaccination: A pooled analysis of four large clinical trials worldwide

Females with existing high-risk HPV (HR-HPV) infections remain at risk of subsequent multiple or recurrent infections, on which benefit from HPV vaccines was under-reported. We pooled individual-level data from four large-scale, RCTs of AS04-HPV-16/18 vaccine to evaluate efficacy and immunogenicity in females DNA-positive to any HR-HPV types at first vaccination. Females receiving the AS04-HPV-16/18 vaccine in the original RCTs constituted the vaccine group in the present study, while those unvaccinated served as the control group. Vaccine efficacy (VE) against new infections and associated cervical intraepithelial neoplasia (CIN) 2+ in females DNA-negative to the considered HR-HPV type but positive to any other HR-HPV types, VE against reinfections in females DNA-positive to the considered HR-HPV type but cleared naturally during later follow-up, and levels of anti-HPV-16/18 IgG were assessed. Our final analyses included 5137 females (vaccine group = 2532, control group = 2605). The median follow-up time was 47.88 months (IQR: 45.72-50.04). For the prevention of precancerous lesions related to the non-infected HR-HPV types at baseline, VE against HPV-16/18 related CIN 2+ was 82.70% (95% CI: 63.70-93.00%). For the prevention of reinfections related to the infected HR-HPV types following natural clearance, VE against HPV-16/18 12MPI was non-significant (p > .05), albeit robust immunity persisted for at least 48 months. Females with existing HR-HPV infections at first vaccination still benefit from vaccination in preventing precancers related to the non-infected types at baseline. VE against reinfections related to the infected types following natural clearance remains to be further investigated.

Pharmaceutical proteins at the interfaces and the role of albumin

A critical measure of the quality of pharmaceutical proteins is the preservation of native conformations of the active pharmaceutical ingredients. Denaturation of the active proteins in any step before administration into patients could lead to loss of potency and/or aggregation, which is associated with an increased risk of immunogenicity of the products. Interfacial stress enhances protein instability as their adsorption to the air-liquid and liquid-solid interfaces are implicated in the formation of denatured proteins and aggregates. While excipients in protein formulations have been employed to reduce the risk of aggregation, the roles of albumin as a stabilizer have not been reviewed from practical and theoretical standpoints. The amphiphilic nature of albumin makes it accumulate at the interfaces. In this review, we aim to bridge the knowledge gap between interfacial instability and the influence of albumin as a surface-active excipient in the context of reducing the immunogenicity risk of protein formulations.

Implementation of a Three-Way Comparability Assessment for a Bioanalytical Anti-Drug Antibody Method

Immunogenicity evaluation is a critical part of drug development. Regulatory guidelines from multiple health agencies provide recommendations for the development and validation of anti-drug antibody (ADA) assays to assess immunogenicity in clinical trials. These recommendations primarily describe an ADA method run in one bioanalytical laboratory supporting a biotherapeutic molecule; however, there are increasing instances that may necessitate the support of the ADA method being run in more than one laboratory. A program can rapidly expand into multiple clinical studies within one or multiple countries, where the most appropriate way to support the program is by having multiple laboratories perform ADA sample analysis. In addition, there may be certain country-specific challenges that may make it infeasible to transport samples outside of the country for analysis. China for example has a lengthy sample exportation process that has potential to negatively impact study timelines. If multiple laboratories analyze samples using the same ADA method, comparable method performance should be established. Here, we describe a three-way assessment of ADA assay comparability between two US-based bioanalytical laboratories and one based in China.

Antibody response to three-dose anti-SARS-CoV-2 mRNA-vaccination in treated solid cancer patients

Solid cancer patients are at higher risk of SARS-CoV-2 infection and severe complications. Moreover, vaccine-induced antibody response is impaired in patients on anticancer treatment. In this retrospective, observational, hypothesis-generating, cohort study, we assessed the antibody response to the third dose of mRNA vaccine in a convenience sample of patients on anticancer treatment, comparing it to that of the primary two-dose cycle. Among 99 patients included, 62.6% were ≥60 years old, 32.3% males, 67.7% with advanced disease. Exactly 40.4% were receiving biological therapy, 16.2% chemotherapy only and 7.1% both treatments. After the third dose, seroconversion rate seems to increase significantly, especially in non-responders to two doses. Heterologous vaccine-type regimen (two-dose mRNA-1273 and subsequent tozinameran or vice versa) results in higher antibody levels. This explorative study suggests that repeated doses of mRNA-vaccines could be associated with a better antibody response in this population. Furthermore, heterologous vaccine-type three-dose vaccination seems more effective in this population. Since this is a hypothesis-generating study, adequately statistically powered studies should validate these results.

Respiratory Syncytial Virus Prefusion F Vaccination: Antibody Persistence and Revaccination

BACKGROUND

Respiratory syncytial virus (RSV) causes substantial respiratory disease. Bivalent RSV prefusion F (RSVpreF) vaccine is licensed in ≥60-year-olds. RSVpreF was well-tolerated and immunogenic in a phase 1/2 study. We evaluated antibody persistence after initial vaccination and safety and immunogenicity after revaccination from this study.

METHODS

Healthy adults were randomized to receive both initial vaccination and revaccination 12 months later with either placebo or RSVpreF 240 µg (±Al(OH)3). RSV-A and RSV-B geometric mean neutralizing titers (GMTs) were measured through 12 months after both vaccinations. Tolerability/safety was assessed.

RESULTS

There were 263 participants revaccinated (18-49-years-old, n=134; 65-85-years-old, n=129). Among 18-49-year-olds and 65-85-year-olds, respectively, geometric mean fold rises (GMFRs) for both RSV subgroups (RSV-A; RSV-B) 1 month after initial RSVpreF vaccination were 13.3-20.4 and 8.9-15.5 compared with levels before initial vaccination; corresponding GMFRs 12 months after initial vaccination were 4.1-5.0 and 2.6-4.1. GMFRs 1 month after revaccination compared with levels before revaccination were 1.4-2.3 and 1.4-2.2 for 18-49-year-olds and 65-85-year-olds, respectively. Peak GMTs after revaccination were lower than those after initial vaccination. GMTs 12 months after initial vaccination and revaccination were similar, with GMFRs ranging from 0.7-1.6. No safety signals occurred.

CONCLUSIONS

RSVpreF revaccination was immunogenic and well-tolerated among adults. NCT03529773.

Immunogenicity of Novel vB_EcoS_NBD2 Bacteriophage-Originated Nanotubes as a Carrier for Peptide-Based Vaccines

Non-infectious virus-like nanoparticles mimic native virus structures and can be modified by inserting foreign protein fragments, making them immunogenic tools for antigen presentation. This study investigated, for the first time, the immunogenicity of long and flexible polytubes formed by yeast-expressed tail tube protein gp39 of bacteriophage vB_EcoS_NBD2 and evaluated their ability to elicit an immune response against the inserted protein fragments. Protein gp39-based polytubes induced humoral immune response in mice, even without the use of adjuvant. Bioinformatics analysis guided the selection of protein fragments from Acinetobacter baumannii for insertion into the C-terminus of gp39. Chimeric polytubes, displaying 28-amino acid long OmpA protein fragment, induced IgG response against OmpA protein fragment in immunized mice. These polytubes demonstrated their effectiveness both as antigen carrier and an adjuvant, when the OmpA fragments were either displayed on chimeric polytubes or used alongside with the unmodified polytubes. Our findings expand the potential applications of long and flexible polytubes, contributing to the development of novel antigen carriers with improved immunogenicity and antigen presentation capabilities.

Reduced effectiveness of repeat influenza vaccination: distinguishing among within-season waning, recent clinical infection, and subclinical infection

Studies have reported that prior-season influenza vaccination is associated with higher risk of clinical influenza infection among vaccinees. This effect might arise from incomplete consideration of within-season waning and recent infection. Using data from the US Flu Vaccine Effectiveness (VE) Network (2011-2012 to 2018-2019 seasons), we found that repeat vaccinees were vaccinated earlier in a season by one week. After accounting for waning VE, repeat vaccinees were still more likely to test positive for A(H3N2) (OR=1.11, 95%CI:1.02-1.21) but not for influenza B or A(H1N1). We found that clinical infection influenced individuals' decision to vaccinate in the following season while protecting against clinical infection of the same (sub)type. However, adjusting for recent clinical infections did not strongly influence the estimated effect of prior-season vaccination. In contrast, we found that adjusting for subclinical infection could theoretically attenuate this effect. Additional investigation is needed to determine the impact of subclinical infections on VE.

Immunogenicity and Vaccine Shedding After 1 or 2 Doses of rVSVΔG-ZEBOV-GP Ebola Vaccine (ERVEBO®): Results From a Phase 2, Randomized, Placebo-controlled Trial in Children and Adults

BACKGROUND

The rVSVΔG-ZEBOV-GP vaccine (ERVEBO®) is a single-dose, live-attenuated, recombinant vesicular stomatitis virus vaccine indicated for the prevention of Ebola virus disease (EVD) caused by Zaire ebolavirus in individuals 12 months of age and older.

METHODS

The Partnership for Research on Ebola VACcination (PREVAC) is a multicenter, phase 2, randomized, double-blind, placebo-controlled trial of 3 vaccine strategies in healthy children (ages 1-17) and adults, with projected 5 years of follow-up (NCT02876328). Using validated assays (GP-ELISA and PRNT), we measured antibody responses after 1-dose rVSVΔG-ZEBOV-GP, 2-dose rVSVΔG-ZEBOV-GP (given on Day 0 and Day 56), or placebo. Furthermore, we quantified vaccine virus shedding in a subset of children's saliva using RT-PCR.

RESULTS

In total, 819 children and 783 adults were randomized to receive rVSVΔG-ZEBOV-GP (1 or 2 doses) or placebo. A single dose of rVSVΔG-ZEBOV-GP increased antibody responses by Day 28 that were sustained through Month 12. A second dose of rVSVΔG-ZEBOV-GP given on Day 56 transiently boosted antibody concentrations. In vaccinated children, GP-ELISA titers were superior to placebo and non-inferior to vaccinated adults. Vaccine virus shedding was observed in 31.7% of children, peaking by Day 7, with no shedding observed after Day 28 post-dose 1 or any time post-dose 2.

CONCLUSIONS

A single dose of rVSVΔG-ZEBOV-GP induced robust antibody responses in children that was non-inferior to the responses induced in vaccinated adults. Vaccine virus shedding in children was time-limited and only observed after the first dose. Overall, these data support the use of rVSVΔG-ZEBOV-GP for the prevention of EVD in at-risk children. Clinical Trials Registration. The study is registered at ClinicalTrials.gov (NCT02876328), the Pan African Clinical Trials Registry (PACTR201712002760250), and the European Clinical Trials Register (EudraCT number: 2017-001798-18).

Optimization of Enzymatic and Chemical Decellularization of Native Porcine Heart Valves for the Generation of Decellularized Xenografts

One of the most important medical interventions for individuals with heart valvular disease is heart valve replacement, which is not without substantial challenges, particularly for pediatric patients. Due to their biological properties and biocompatibility, natural tissue-originated scaffolds derived from human or animal sources are one type of scaffold that is widely used in tissue engineering. However, they are known for their high potential for immunogenicity. Being free of cells and genetic material, decellularized xenografts, consequently, have low immunogenicity and, thus, are expected to be tolerated by the recipient's immune system. The scaffold ultrastructure and ECM composition can be affected by cell removal agents. Therefore, applying an appropriate method that preserves intact the structure of the ECM plays a critical role in the final result. So far, there has not been an effective decellularization technique that preserves the integrity of the heart valve's ultrastructure while securing the least amount of genetic material left. This study demonstrates a new protocol with untraceable cells and residual DNA, thereby maximally reducing any chance of immunogenicity. The mechanical and biochemical properties of the ECM resemble those of native heart valves. Results from this study strongly indicate that different critical factors, such as ionic detergent omission, the substitution of Triton X-100 with Tergitol, and using a lower concentration of trypsin and a higher concentration of DNase and RNase, play a significant role in maintaining intact the ultrastructure and function of the ECM.

Harnessing RNA Technology to Advance Therapeutic Vaccine Antigens against Chagas Disease

Chagas disease (CD) (American trypanosomiasis caused by Trypanosoma cruzi) is a parasitic disease endemic in 21 countries in South America, with increasing global spread. When administered late in the infection, the current antiparasitic drugs do not prevent the onset of cardiac illness leading to chronic Chagasic cardiomyopathy. Therefore, new therapeutic vaccines or immunotherapies are under development using multiple platforms. In this study, we assessed the feasibility of developing an mRNA-based therapeutic CD vaccine targeting two known T. cruzi vaccine antigens (Tc24─a flagellar antigen and ASP-2─an amastigote antigen). We present the mRNA engineering steps, preparation, and stability of the lipid nanoparticles and evaluation of their uptake by dendritic cells, as well as their biodistribution in c57BL/J mice. Furthermore, we assessed the immunogenicity and efficacy of two mRNA-based candidates as monovalent and bivalent vaccine strategies using an in vivo chronic mouse model of CD. Our results show several therapeutic benefits, including reductions in parasite burdens and cardiac inflammation, with each mRNA antigen, especially with the mRNA encoding Tc24, and Tc24 in combination with ASP-2. Therefore, our findings demonstrate the potential of mRNA-based vaccines as a therapeutic option for CD and highlight the opportunities for developing multivalent vaccines using this approach.

Boosting the immunogenicity of the CoronaVac SARS-CoV-2 inactivated vaccine with Huoxiang Suling Shuanghua Decoction: a randomized, double-blind, placebo-controlled study

Introduction

In light of the public health burden of the COVID-19 pandemic, boosting the safety and immunogenicity of COVID-19 vaccines is of great concern. Numerous Traditional Chinese medicine (TCM) preparations have shown to beneficially modulate immunity. Based on pilot experiments in mice that showed that supplementation with Huoxiang Suling Shuanghua Decoction (HSSD) significantly enhances serum anti-RBD IgG titers after inoculation with recombinant SARS-CoV-2 S-RBD protein, we conducted this randomized, double-blind, placebo-controlled clinical trial aimed to evaluate the potential immunogenicity boosting effect of oral HSSD after a third homologous immunization with Sinovac's CoronaVac SARS-CoV-2 (CVS) inactivated vaccine.

Methods

A total of 70 participants were randomly assigned (1:1 ratio) to receive a third dose of CVS vaccination and either oral placebo or oral HSSD for 7 days. Safety aspects were assessed by recording local and systemic adverse events, and by blood and urine biochemistry and liver and kidney function tests. Main outcomes evaluated included serum anti-RBD IgG titer, T lymphocyte subsets, serum IgG and IgM levels, complement components (C3 and C4), and serum cytokines (IL-6 and IFN-γ). In addition, metabolomics technology was used to analyze differential metabolite expression after supplementation with HSSD.

Results

Following a third CVS vaccination, significantly increased serum anti-RBD IgG titer, reduced serum IL-6 levels, increased serum IgG, IgM, and C3 and C4 levels, and improved cellular immunity, evidenced by reduce balance deviations in the distribution of lymphocyte subsets, was observed in the HSSD group compared with the placebo group. No serious adverse events were recorded in either group. Serum metabolomics results suggested that the mechanisms by which HSSD boosted the immunogenicity of the CVS vaccine are related to differential regulation of purine metabolism, vitamin B6 metabolism, folate biosynthesis, arginine and proline metabolism, and steroid hormone biosynthesis.

Conclusion

Oral HSSD boosts the immunogenicity of the CVS vaccine in young and adult individuals. This trial provides clinical reference for evaluation of TCM immunomodulators to improve the immune response to COVID-19 vaccines.

Cross-Reactive Polyclonal Antibodies Raised Against GalNAc-Conjugated siRNA Recognize Mostly the GalNAc Moiety

Small interfering RNA (siRNA) is gaining momentum as a therapeutic modality with six approved products. Since siRNA has the potential to elicit undesired immune responses in patients, immunogenicity assessment is required during clinical development by regulatory authorities. In this study, anti-siRNA polyclonal antibodies were generated through animal immunization. These cross-reactive polyclonal antibodies recognized mostly the N-acetylgalactosamine (GalNAc) moiety with a small fraction against sequence-independent epitopes. We demonstrate that the polyclonal antibodies can be utilized as immunogenicity assay positive controls for the same class of GalNAc-conjugated siRNAs. In addition, anti-GalNAc mAbs showed desired sensitivity and drug tolerance, supporting their use as alternative surrogate positive controls. These findings can guide positive control selection and immunogenicity assay development for GalNAc-conjugated siRNAs and other oligonucleotide therapeutics.

The serological immunogenicity of the third and fourth doses of COVID-19 vaccine in patients with inflammatory rheumatic diseases on different biologic or targeted DMARDs: a Swedish nationwide study (COVID-19-REUMA)

Studies investigating the immunogenicity of additional COVID-19 vaccine doses in immunosuppressed patients with inflammatory rheumatic diseases (IRD) are still limited. The objective was to explore the antibody response including response to omicron virus subvariants (sBA.1 and sBS.2) after third and fourth COVID-19 vaccine doses in Swedish IRD patients treated with immunomodulating drugs compared to controls. Antibody levels to spike wild-type antigens (full-length protein and S1) and the omicron variants sBA.1 and sBA.2 (full-length proteins) were measured. A positive response was defined as having antibody levels over cut-off or ≥fourfold increase in post-vaccination levels for both antigens. Patients with arthritis, vasculitis, and other autoimmune diseases (n = 414), and controls (n = 61) receiving biologic/targeted synthetic disease-modifying anti-rheumatic drugs (DMARDs) with or without conventional synthetic DMARDs participated. Of these, blood samples were available for 370 patients and 52 controls after three doses, and 65 patients and 15 controls after four doses. Treatment groups after three vaccine doses were rituximab (n = 133), abatacept (n = 22), IL6r inhibitors (n = 71), JAnus Kinase inhibitors (JAK-inhibitors) (n = 56), tumor necrosis factor inhibitor (TNF-inhibitors) (n = 61), IL12/23/17 inhibitors (n = 27), and controls (n = 52). The percentage of responders after three and four vaccine doses was lower in rituximab-treated patients (59% and 57%) compared to controls (100%) (P < 0.001). After three doses, the percentage of responders in all other groups was 100%, including response to omicron sBA.1 and sBA.2. In rituximab-treated patients, higher baseline immunoglobulin G (IgG) and longer time-period between rituximab and vaccination predicted better response. In this Swedish nationwide study including IRD patients three and four COVID-19 vaccine doses were immunogenic in patients treated with IL6r inhibitors, TNF-inhibitors, JAK-inhibitors, and IL12/23/17-inhibitors but not in rituximab. As >50% of rituximab patients responded to vaccines including omicron subvariants, these patients should be prioritized for additional vaccine doses.

IMPORTANCE

Results from this study provide further evidence that additional doses of COVID-19 vaccines are immunogenic and result in satisfactory antibody response in a majority of patients with inflammatory rheumatic diseases (IRD) receiving potent immunomodulating treatments such as biological or targeted disease-modifying anti-rheumatic drugs (DMARDs) given as monotherapy or combined with traditional DMARDs. We observed that rituximab treatment, both as monotherapy and combined with csDMARDs, impaired antibody response, and only roughly 50% of patients developed a satisfactory antibody response including response to omicron subvariants after the third vaccine. In addition, higher IgG levels at the last rituximab course before the third vaccine dose and a longer time after the last rituximab treatment increased the chance of a satisfactory antibody response. These results indicate that rituximab-treated patients should be prioritized for additional vaccine doses.

CLINICAL TRIALS

EudraCT (European Union Drug Regulating Authorities Clinical Trials Database) with number 2021-000880-63.

A High Threshold of Biotherapeutic Aggregate Numbers is Needed to Induce an Immunogenic Response In Vitro, In Vivo, and in the Clinic

BACKGROUND AND PURPOSE

There is concern that subvisible aggregates in biotherapeutic drug products pose a risk to patient safety. We investigated the threshold of biotherapeutic aggregates needed to induce immunogenic responses.

METHODS AND RESULTS

Highly aggregated samples were tested in cell-based assays and induced cellular responses in a manner that depended on the number of particles. The threshold of immune activation varied by disease state (cancer, rheumatoid arthritis, allergy), concomitant therapies, and particle number. Compared to healthy donors, disease state patients showed an equal or lower response at the late phase (7 days), suggesting they may not have a higher risk of responding to aggregates. Xeno-het mice were used to assess the threshold of immune activation in vivo. Although highly aggregated samples (~ 1,600,000 particles/mL) induced a weak and transient immunogenic response in mice, a 100-fold dilution of this sample (~ 16,000 particles/mL) did not induce immunogenicity. To confirm this result, subvisible particles (up to ~ 18,000 particles/mL, containing aggregates and silicone oil droplets) produced under representative administration practices (created upon infusion of a drug product through an IV catheter) did not induce a response in cell-based assays or appear to increase the rate of adverse events or immunogenicity during phase 3 clinical trials.

CONCLUSION

The ability of biotherapeutic aggregates to elicit an immune response in vitro, in vivo, and in the clinic depends on high numbers of particles. This suggests that there is a high threshold for aggregates to induce an immunogenic response which is well beyond that seen in standard biotherapeutic drug products.

A Randomized, Single-Dose, Parallel-Controlled Phase 1 Clinical Comparison of an Omalizumab Biosimilar Candidate with Reference Omalizumab in Healthy Chinese Male Volunteers

This study evaluated the bioequivalence of omalizumab, a humanized monoclonal antibody against immunoglobulin-E (IgE), with one of its biosimilar candidates. The study was designed as a randomized, double-blind, parallel-controlled trial. A total of subjects who met the inclusion criteria and did not meet the exclusion criteria were dynamically randomly assigned to receive the test drug or the reference drug with a single subcutaneous injection of 150 mg by the minimization method. The test group and the reference group had similar demographic characteristics and baseline characteristics of total IgE. The 90% confidence interval of the geometric average ratio of the area under the serum concentration-time curve from the time 0 to the time of last quantifiable concentration, the area under the serum concentration curve from time 0 to infinity, and the maximum observed serum concentration between the 2 groups were within 80%-125%, showing bioequivalence. The changing trend of total and free IgE in the 2 groups was similar after administration, proving the pharmacodynamic similarity. The 2 groups had no significant difference in the positive rate of antidrug antibodies, and the total positive rate of neutralizing antibodies was 0. The incidence of treatment-emergent adverse events and treatment-related adverse events were similar between the 2 groups, with no serious adverse events. This study shows that the test drug had similar pharmacokinetics, immunogenicity, and safety to the reference omalizumab in healthy male subjects.

Safety, immunogenicity, and protective effective of inhaled COVID-19 vaccines: A systematic review and meta-analysis

This study aimed to examine the safety, immunogenicity and protective effective of inhaled COVID-19 vaccines (ICVs). Literature research was done through EMBASE, Cochrane, PubMed, and Web of Science up to 10 March 2024. Pooled estimates with corresponding 95% confidence intervals (CI) were computed and compared using the random effects and common effects model. Of the 15 studies, 11 analyzed safety, 13 analyzed immunogenicity, and 3 analyzed protective effective. The results showed a favorable safety profile of ICVs for primary vaccination series, however it does not always seem to produce the expected immune response and protective effective. Meta-analysis of ICVs booster vaccinations (BVs) showed that the levels of neutralizing antibody Geometric mean titer (nAb-GMT) with aerosolised Ad5-nCoV (AAd5-nCoV) were all higher than those with inactivated vaccine (INA-nCoV) (standard mean difference (SMD) = 2.32; 95% CI: 1.96-2.69) and intramuscular Ad5-nCoV (IMAd5-nCoV) (SMD = 0.31; 95% CI: 0.14-0.48) against the original strain of SARS-CoV-2. Importantly, we also observed similar results in the omicron variant. In addition, ICV in BVs has high mucosal immunity to IgA antibodies. The risk of adverse events was comparable or lower for AAd5-nCoV compared to INA-nCoV or IMAd5-nCoV. Current evidence shows that the safety profile of ICVs were well. The booster dose of AAd5-nCoV had a high immune response (including mucosal immunity) and provided protection against COVID-19 caused by the SARS-CoV-2 omicron variant. Further studies are needed to investigate the long-term safety of intranasal vaccine booster protection and various types of ICVs.

Immunogenicity, efficacy, and safety of biosimilar insulin glargine (Gan & Lee glargine) compared with originator insulin glargine (Lantus®) in patients with type 2 diabetes after 26 weeks' treatment: A randomized open label study

AIM

To evaluate the equivalence of immunogenicity, safety and efficacy of Gan & Lee (GL) Glargine (Basalin®; Gan & Lee Pharmaceutical) with that of the reference product (Lantus®) in adult participants with type 2 diabetes mellitus.

METHODS

This was a phase 3, multicenter, open-label, equivalence trial conducted across 57 sites. In total, 567 participants with type 2 diabetes mellitus were randomized in a 1:1 ratio to undergo treatment with either GL Glargine or Lantus® for 26 weeks. The primary endpoint was the proportion of participants in each treatment arm who manifested treatment-induced anti-insulin antibodies (AIA). Secondary endpoints included efficacy and safety metrics, changes in glycated haemoglobin levels, and a comparative assessment of adverse events. Results were analysed using an equivalence test comparing the limits of the 90% confidence interval (CI) for treatment-induced AIA development to the prespecified margins.

RESULTS

The percentages of participants positive for treatment-induced glycated haemoglobin by week 26 were similar between the GL Glargine (19.2%) and Lantus® (21.3%) treatment groups, with a treatment difference of -2.1 percentage points and a 90% CI (-7.6%, 3.5%) (predefined similarity margins: -10.7%, 10.7%). The difference in glycated haemoglobin was -0.08% (90% CI, -0.23, 0.06). The overall percentage of participants with any treatment-emergent adverse events was similar between the GL Glargine (80.1%) and Lantus® (81.6%) treatment groups.

CONCLUSIONS

GL Glargine was similar to Lantus® in terms of immunogenicity, efficacy, and safety, based on the current study.

Effect of Secukinumab and Tumor Necrosis Factor Inhibitors on Humoral Response to BNT162b2 mRNA Vaccine in Patients With Spondyloarthritis Compared to Immunocompetent Controls

OBJECTIVE

To assess the humoral response to the BNT162b2 mRNA vaccine among patients with spondyloarthritis (SpA) receiving secukinumab (SEC) compared to those receiving tumor necrosis factor inhibitors (TNFi) and immunocompetent controls.

METHODS

Consecutive patients with psoriatic arthritis or axial SpA receiving SEC (n = 37) or TNFi (monotherapy, n = 109; + methotrexate [MTX], n = 16), immunocompetent controls (n = 122), and patients with rheumatoid arthritis (RA) receiving TNFi therapy (controls, n = 50) were vaccinated with 2 or 3 doses of the BNT162b2 vaccine. We evaluated humoral response, adverse events, and disease activity, and monitored for breakthrough coronavirus disease 2019 (COVID-19) postvaccination.

RESULTS

The 2-dose vaccine regimen induced a comparable seropositive response in all study groups. S1/S2 antibody titers (in binding antibody units/mL; mean [SD]) were higher in the SEC group vs the TNFi + MTX-SpA and TNFi-RA groups (192.5 [68.4] vs 104.6 [46.9], P < 0.001, and 143.1 [81.9], P = 0.004). After 6 months, 96.3%, 96.6%, and 80.9% of the SEC, immunocompetent, and TNFi monotherapy-SpA groups (P = 0.10), respectively; 66.7% of the TNFi + MTX-SpA group (P = 0.03); and 63% of the TNFi-RA group (P = 0.004) remained seropositive. S1/S2 antibody titer decline was steeper in the TNFi groups than the SEC group. After the third dose, 100% of the SpA and immunocompetent and 88.9% of the TNFi-RA (P = 0.25) groups were seropositive. Rate of breakthrough COVID-19 infection was higher in the TNFi groups than in the SEC group (36-37.5% vs 10.8%). No significant between-group differences were observed for postvaccination disease activity and adverse events.

CONCLUSION

SEC did not interfere with the immunogenic response to BNT162b2 vaccine in patients with SpA; however, TNFi therapy was associated with lower S1/S2-antibody titers, faster decline, and higher rate of breakthrough infections.

A meta-analysis of immunogenicity and safety of two versus single-doses of influenza A (H1N1) vaccine in person living with HIV

Purpose: Influenza vaccination of person living with HIV (PLWH) is a powerful means to tackle severe clinical outcomes. Few data on two doses of influenza vaccine in PLWH are available.Research Design: To evaluate the immunogenicity and safety of two doses of vaccine as compared with single dose in PLWH, we searched Pubmed, Embase, and web of science databases for relevant articles (January 2009 to April 2023). Pooled SMD or RR and 95% CI were calculated.Results: A total of 2436 participants from 14 studies were included. Compared to single dose influenza vaccine regimen, the pooled RR of seroprotection and seroconversion for two doses of vaccines was 1.14 (95%CI: 1.08-1.21) and 1.25 (95%CI: 1.16-1.34), respectively; the SMD of GMT was 0.42 (95%CI: 0.35, 0.49). Regarding safety, the fever risk in PLWH receiving two doses of vaccine was 3.42 fold higher than that of single dose vaccine, and the risk of myalgia had a quarter reduction. No serious vaccine-related adverse events were reported.Conclusions: Collectively, two doses of the vaccine are associated with a better immunogenicity and an acceptable safety in PLWH. Two doses of the adjuvant vaccination might be a superior vaccination regimen.nation regimen.

Eliminating drug target interference with specific antibody or its F(ab')2 fragment in the bridging immunogenicity assay

Background: DB-1003 is a humanized anti-IgE monoclonal antibody with higher affinity than omalizumab. In the affinity capture elution (ACE)-based bridging electrochemiluminescent immunoassay (ECLIA) for antibodies to DB-1003, monkey serum IgE caused false-positive results. Materials & methods: The target-specific antibody or its F(ab')2 fragment was used to mitigate drug target interference in an ACE-based bridging ECLIA for the detection of anti-DB-1003 antibodies. Results: The sensitivity of the developed assay was at least 100 ng/ml. When the anti-drug antibody concentration was 250 ng/ml, the assay tolerated at least 20.0 μg/ml of the monkey IgE. Conclusion: Incorporating the target-specific antibody or its F(ab')2 fragment can overcome the interference from monkey serum IgE in ACE-based bridging ECLIA for anti-DB-1003 antibody detection.

Immunogenicity and safety of BNT162b2 vaccination in adolescents with systemic lupus erythematosus

OBJECTIVES

We evaluated the immunogenicity and safety of BNT162b2 vaccination in adolescents with systemic lupus erythematosus (adoSLE) receiving either high- or low-dose immunosuppressant (High-IS and Low-IS).

METHODS

Patients aged 12-18 years diagnosed with SLE were enrolled. High-IS was defined as >7.5 mg/day prednisolone or with other immunosuppressant, while Low-IS was defined as only ≤7.5 mg/day of prednisolone and no immunosuppressant. Two doses of BNT162b2 vaccination were given 4 weeks apart, followed by a booster (third) dose at 4-6 months later. Anti-spike receptor binding domain (anti-RBD) IgG against Wuhan, neutralising antibody (NT) against Wuhan and Omicron variants, and cellular immune response by IFN-γ-ELISpot assay were evaluated following vaccination. Adverse events (AEs) and SLE flare were monitored.

RESULTS

A total of 73 participants were enrolled, 40 and 33 in the High-IS and Low-IS group, respectively. At 4 weeks following the 2nd dose, overall anti-RBD IgG seropositivity was 97.3%, with no difference between the groups (p = .498). AdoSLE on High-IS had lower anti-RBD IgG (p < .001), Wuhan NT (p < .001), and IFN-γ-ELISpot (p = .022) than those on Low-IS. A 3rd dose induced significantly higher antibody responses than after the 2nd dose (p < .001) in both groups and established seroconversion against Omicron variants, with persistent lower antibody levels in High-IS group. SELENA-SLEDAI scores within 12 weeks after 2-dose vaccination was higher than before vaccination (3.1 vs 2.5; p < .036); however, the occurrence of disease flare by SELENA-SLEDAI flare index was not different after vaccination compared to before vaccination, consistent across groups. Non-severe AEs occurred similarly in both groups.

CONCLUSION

AdoSLE on High-IS induced lower SARS-CoV-2 vaccine immune responses than Low-IS. Vaccination can increase disease activity and requires close monitoring for disease flare.

2023 White Paper on Recent Issues in Bioanalysis: ISR for ADA Assays, the Rise of dPCR vs qPCR, International Reference Standards for Vaccine Assays, Anti-AAV TAb Post-Dose Assessment, NanoString Validation, ELISpot as Gold Standard (Part 3 - Recommendations on Gene Therapy, Cell Therapy, Vaccines Immunogenicity & Technologies; Biotherapeutics Immunogenicity & Risk Assessment; ADA/NAb Assay/Reporting Harmonization)

The 17th Workshop on Recent Issues in Bioanalysis (17th WRIB) took place in Orlando, FL, USA on June 19-23, 2023. Over 1000 professionals representing pharma/biotech companies, CROs, and multiple regulatory agencies convened to actively discuss the most current topics of interest in bioanalysis. The 17th WRIB included 3 Main Workshops and 7 Specialized Workshops that together spanned 1 week to allow an exhaustive and thorough coverage of all major issues in bioanalysis of biomarkers, immunogenicity, gene therapy, cell therapy and vaccines. Moreover, in-depth workshops on "EU IVDR 2017/746 Implementation and impact for the Global Biomarker Community: How to Comply with these NEW Regulations" and on "US FDA/OSIS Remote Regulatory Assessments (RRAs)" were the special features of the 17th edition. As in previous years, WRIB continued to gather a wide diversity of international, industry opinion leaders and regulatory authority experts working on both small and large molecules as well as gene, cell therapies and vaccines to facilitate sharing and discussions focused on improving quality, increasing regulatory compliance, and achieving scientific excellence on bioanalytical issues. This 2023 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2023 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers the recommendations on Gene Therapy, Cell therapy, Vaccines and Biotherapeutics Immunogenicity. Part 1A (Mass Spectrometry Assays and Regulated Bioanalysis/BMV), P1B (Regulatory Inputs) and Part 2 (Biomarkers, IVD/CDx, LBA and Cell-Based Assays) are published in volume 16 of Bioanalysis, issues 8 and 9 (2024), respectively.

Qualitative, rather than quantitative, differences between HLA-DQ alleles affect HLA-DQ immunogenicity in organ transplantation

Prolonging the lifespan of transplanted organs is critical to combat the shortage of this life-saving resource. Chronic rejection, with irreversible demise of the allograft, is often caused by the development of donor-specific HLA antibodies. Currently, enumerating molecular (amino acid) mismatches between recipient and donor is promoted to identify patients at higher risk of developing HLA antibodies, for use in organ allocation, and immunosuppression-minimization strategies. We have counseled against the incorporation of such approaches into clinical use and hypothesized that not all molecular mismatches equally contribute to generation of donor-specific immune responses. Herein, we document statistical shortcomings in previous study design: for example, use of individuals who lack the ability to generate donor-specific-antibodies (HLA identical) as part of the negative cohort. We provide experimental evidence, using CRISPR-Cas9-edited cells, to rebut the claim that the HLAMatchmaker eplets represent "functional epitopes." We further used unique sub-cohorts of patients, those receiving an allograft with two HLA-DQ mismatches yet developing antibodies only to one mismatch (2MM1DSA), to interrogate differential immunogenicity. Our results demonstrate that mismatches of DQα05-heterodimers exhibit the highest immunogenicity. Additionally, we demonstrate that the DQα chain critically contributes to the overall qualities of DQ molecules. Lastly, our data proposes that an augmented risk to develop donor-specific HLA-DQ antibodies is dependent on qualitative (evolutionary and functional) divergence between recipient and donor, rather than the mere number of molecular mismatches. Overall, we propose an immunological mechanistic rationale to explain differential HLA-DQ immunogenicity, with potential ramifications for other pathological processes such as autoimmunity and infections.

Immunoprotection of FliBc chimeric fiber2 fusion proteins targeting dendritic cells against Fowl adenovirus serotype 4 infection

Hepatitis-hydropericardium syndrome (HHS) is a highly fatal disease in chickens caused by the highly pathogenic fowl adenovirus serotype 4 (FAdV-4), which has severe economic consequences. The fiber2 protein exhibits excellent potential as a candidate for a subunit vaccination against FAdV-4. Despite having a high safety profile, subunit vaccines have low immunogenicity due to their lack of infectivity, which leads to low levels of immune response. As a vaccine adjuvant, Salmonella flagellin possesses the potential to augment the immunological response to vaccinations. Additionally, a crucial strategy for enhancing vaccine efficacy is efficient presentation of immune antigens to dendritic cells (DC) for targeted vaccination. In this study, we designed FAdV-4-fiber2 protein, and a recombinant protein called FliBc-fiber2-SP which based on FAdV-4-fiber2 protein, was generated using the gene sequence FliBc, which retains only the conserved sequence at the amino and carboxyl termini of the flagellin B subunit, and a short peptide SPHLHTSSPWER (SP), which targets chicken bone marrow-derived DC. They were separately administered via intramuscular injection to 14-day-old specific pathogen-free (SPF) chickens, and their immunogenicity was compared. At 21 d postvaccination (dpv), it was found that the FliBc-fiber2-SP recombinant protein elicited significantly higher levels of IgG antibodies and conferred a vaccine protection rate of up to 100% compared to its counterpart fiber2 protein. These results suggest that the DC-targeted peptide fusion strategy for flagellin chimeric antigen construction can effectively enhance the immune protective efficacy of antigen proteins.

Codon-optimization in gene therapy: promises, prospects and challenges

Codon optimization has evolved to enhance protein expression efficiency by exploiting the genetic code's redundancy, allowing for multiple codon options for a single amino acid. Initially observed in E. coli, optimal codon usage correlates with high gene expression, which has propelled applications expanding from basic research to biopharmaceuticals and vaccine development. The method is especially valuable for adjusting immune responses in gene therapies and has the potenial to create tissue-specific therapies. However, challenges persist, such as the risk of unintended effects on protein function and the complexity of evaluating optimization effectiveness. Despite these issues, codon optimization is crucial in advancing gene therapeutics. This study provides a comprehensive review of the current metrics for codon-optimization, and its practical usage in research and clinical applications, in the context of gene therapy.

SARS-CoV-2-specific mucosal immune response in vaccinated versus infected children

The anti-COVID-19 intramuscular vaccination induces a strong systemic but a weak mucosal immune response in adults. Little is known about the mucosal immune response in children infected or vaccinated against SARS-CoV-2. We found that 28% of children had detectable salivary IgA against SARS-CoV-2 even before vaccination, suggesting that, in children, SARS-CoV-2 infection may be undiagnosed. After vaccination, only receptor-binding domain (RBD)-specific IgA1 significantly increased in the saliva. Conversely, infected children had significantly higher salivary RBD-IgA2 compared to IgA1, indicating that infection more than vaccination induces a specific mucosal immune response in children. Future efforts should focus on development of vaccine technologies that also activate mucosal immunity.

The evaluation of cystatin protein vaccines based on the stress response of ticks triggered by low-temperature and toxin stress in Haemaphysalis doenitzi

BACKGROUND

Ticks, which are obligate blood-feeding parasites, transmit a wide range of pathogens during their hematophagic process. Certain enzymes and macromolecules play a crucial role in inhibition of several tick physiological processes, including digestion and reproduction. In the present study, genes encoding type 2 cystatin were cloned and characterized from Haemaphysalis doenitzi, and the potential role of cystatin in tick control was further assessed.

RESULTS

Two cystatin genes, HDcyst-1 and HDcyst-2, were successfully cloned from the tick H. doenitzi. Their open reading frames are 390 and 426 base pairs, and the number of coding amino acids are 129 and 141, respectively. In the midgut, salivary glands, Malpighian tubules and ovaries of ticks, the relative expression of HDcyst-1 was higher in the midgut and Malpighian tubules, and HDcyst-2 was higher in the salivary glands of H. doenitzi, respectively. Lipopolysaccharide (LPS) injection and low-temperature stress elevated cystatin expression in ticks. Enzyme-linked immunosorbent assay showed that both rHDcyst-1 and rHDcyst-2 protein vaccines increased antibody levels in immunized rabbits. A vaccination trial in rabbits infected with H. doenitzi showed that both recombinant cystatin proteins significantly reduced tick engorgement weights and egg mass weight, in particular, rHDcyst-1 significantly prolonged tick engorgement time by 1 day and reduced egg hatching rates by 16.9%. In total, rHDcyst-1 and rHDcyst-2 protein vaccinations provided 64.1% and 51.8% protection to adult female ticks, respectively.

CONCLUSION

This is the first report on the immunological characterization of the cystatin protein and sequencing of the cystatin gene in H. doenitzi. Cystatin proteins are promising antigens that have the potential to be used as vaccines for infestation of H. doenitzi control. © 2024 Society of Chemical Industry.

Phase 1, first-in-human study of TYRP1-TCB (RO7293583), a novel TYRP1-targeting CD3 T-cell engager, in metastatic melanoma: active drug monitoring to assess the impact of immune response on drug exposure

Introduction

Although checkpoint inhibitors (CPIs) have improved outcomes for patients with metastatic melanoma, those progressing on CPIs have limited therapeutic options. To address this unmet need and overcome CPI resistance mechanisms, novel immunotherapies, such as T-cell engaging agents, are being developed. The use of these agents has sometimes been limited by the immune response mounted against them in the form of anti-drug antibodies (ADAs), which is challenging to predict preclinically and can lead to neutralization of the drug and loss of efficacy.

Methods

TYRP1-TCB (RO7293583; RG6232) is a T-cell engaging bispecific (TCB) antibody that targets tyrosinase-related protein 1 (TYRP1), which is expressed in many melanomas, thereby directing T cells to kill TYRP1-expressing tumor cells. Preclinical studies show TYRP1-TCB to have potent anti-tumor activity. This first-in-human (FIH) phase 1 dose-escalation study characterized the safety, tolerability, maximum tolerated dose/optimal biological dose, and pharmacokinetics (PK) of TYRP1-TCB in patients with metastatic melanoma (NCT04551352).

Results

Twenty participants with cutaneous, uveal, or mucosal TYRP1-positive melanoma received TYRP1-TCB in escalating doses (0.045 to 0.4 mg). All participants experienced ≥1 treatment-related adverse event (TRAE); two participants experienced grade 3 TRAEs. The most common toxicities were grade 1-2 cytokine release syndrome (CRS) and rash. Fractionated dosing mitigated CRS and was associated with lower levels of interleukin-6 and tumor necrosis factor-alpha. Measurement of active drug (dual TYPR1- and CD3-binding) PK rapidly identified loss of active drug exposure in all participants treated with 0.4 mg in a flat dosing schedule for ≥3 cycles. Loss of exposure was associated with development of ADAs towards both the TYRP1 and CD3 domains. A total drug PK assay, measuring free and ADA-bound forms, demonstrated that TYRP1-TCB-ADA immune complexes were present in participant samples, but showed no drug activity in vitro.

Discussion

This study provides important insights into how the use of active drug PK assays, coupled with mechanistic follow-up, can inform and enable ongoing benefit/risk assessment for individuals participating in FIH dose-escalation trials. Translational studies that lead to a better understanding of the underlying biology of cognate T- and B-cell interactions, ultimately resulting in ADA development to novel biotherapeutics, are needed.

Construction of recombinant pseudorabies virus expressing PCV2 Cap, PCV3 Cap, and IL-4: investigation of their biological characteristics and immunogenicity

Background

Porcine circovirus type 2 (PCV2) is a globally prevalent and recurrent pathogen that primarily causes slow growth and immunosuppression in pigs. Porcine circovirus type 3 (PCV3), a recently discovered virus, commonly leads to reproductive disorders in pigs and has been extensively disseminated worldwide. Infection with a single PCV subtype alone does not induce severe porcine circovirus-associated diseases (PCVD), whereas concurrent co-infection with PCV2 and PCV3 exacerbates the clinical manifestations. Pseudorabies (PR), a highly contagious disease in pigs, pose a significant threat to the swine industry in China.

Methods

In this study, recombinant strains named rPRV-2Cap/3Cap and rPRV-2Cap/3Cap/IL4 was constructed by using a variant strain XJ of pseudorabies virus (PRV) as the parental strain, with the TK/gE/gI genes deleted and simultaneous expression of PCV2 Cap, PCV3 Cap, and IL-4. The two recombinant strains obtained by CRISPR/Cas gE gene editing technology and homologous recombination technology has genetic stability in baby hamster Syrian kidney-21 (BHK-21) cells and is safe to mice.

Results

rPRV-2Cap/3Cap and rPRV-2Cap/3Cap/IL4 exhibited good safety and immunogenicity in mice, inducing high levels of antibodies, demonstrated 100% protection against the PRV challenge in mice, reduced viral loads and mitigated pathological changes in the heart, lungs, spleen, and lymph nodes during PCV2 challenge. Moreover, the recombinant viruses with the addition of IL-4 as a molecular adjuvant outperformed the non-addition group in most indicators.

Conclusion

rPRV-2Cap/3Cap and rPRV-2Cap/3Cap/IL4 hold promise as recombinant vaccines for the simultaneous prevention of PCV2, PCV3, and PRV, while IL-4, as a vaccine molecular adjuvant, effectively enhances the immune response of the vaccine.

Deglycosylated RBD produced in Pichia pastoris as a low-cost sera COVID-19 diagnosis tool and a vaccine candidate

During the COVID-19 outbreak, numerous tools including protein-based vaccines have been developed. The methylotrophic yeast Pichia pastoris (synonymous to Komagataella phaffii) is an eukaryotic cost-effective and scalable system for recombinant protein production, with the advantages of an efficient secretion system and the protein folding assistance of the secretory pathway of eukaryotic cells. In a previous work, we compared the expression of SARS-CoV-2 Spike Receptor Binding Domain in P. pastoris with that in human cells. Although the size and glycosylation pattern was different between them, their protein structural and conformational features were indistinguishable. Nevertheless, since high mannose glycan extensions in proteins expressed by yeast may be the cause of a nonspecific immune recognition, we deglycosylated RBD in native conditions. This resulted in a highly pure, homogenous, properly folded and monomeric stable protein. This was confirmed by circular dichroism and tryptophan fluorescence spectra and by SEC-HPLC, which were similar to those of RBD proteins produced in yeast or human cells. Deglycosylated RBD was obtained at high yields in a single step, and it was efficient in distinguishing between SARS-CoV-2-negative and positive sera from patients. Moreover, when the deglycosylated variant was used as an immunogen, it elicited a humoral immune response ten times greater than the glycosylated form, producing antibodies with enhanced neutralizing power and eliciting a more robust cellular response. The proposed approach may be used to produce at a low cost, many antigens that require glycosylation to fold and express, but do not require glycans for recognition purposes.

Novel assay format for total anti-adeno-associated virus antibody detection with low capsid consumption and built-in specificity control

Aim: To develop an assay format for detection of total anti-adeno-associated virus 2 (AAV2) antibodies with low capsid material consumption. Methods: An immune complex (IC) assay format was developed. The format is based on the formation of ICs in solution and their subsequent detection using an anti-AAV2 antibody for capture and an antibody against the study species IgG for detection. Results: The feasibility of the IC assay for detection of preexisting and treatment-emergent anti-AAV2 antibodies was demonstrated in cynomolgus monkey and human serum samples, including samples from a preclinical study with AAV2-based therapies. Conclusion: The presented IC assay is an easy-to-perform total anti-AAV2 antibody assay that requires a small amount of unlabeled capsid material and provides an intrinsic specificity control.

RTS,S/AS02A Malaria Vaccine-Induced IgG Responses Equally Recognize Native-Like Fucosylated and Nonfucosylated Plasmodium falciparum Circumsporozoite Proteins

The RTS,S/AS02A malaria vaccine is based on the Plasmodium falciparum circumsporozoite protein (PfCSP), which is O-fucosylated on the sporozoite surface. We determined whether RTS,S/AS02A-induced immunoglobulin G (IgG) antibodies recognize vaccine-like nonfucosylated PfCSP better than native-like fucosylated PfCSP. Similar to previous vaccine trials, RTS,S/AS02A vaccination induced high anti-PfCSP IgG levels associated with malaria protection. IgG recognition of nonfucosylated and fucosylated PfCSP was equivalent, suggesting that PfCSP fucosylation does not affect antibody recognition. Clinical Trials Registration. NCT00197041.

Implications of Immunogenicity Testing for Therapeutic Monoclonal Antibodies: A Quantitative Pharmacology Framework

The interpretation of immunogenicity results for a mAb product and prediction of its clinical consequences remain difficult, despite enormous advances in methodologies and efforts toward the best practice for consistent data generation and reporting. To this end, the contribution from the clinical pharmacology discipline has been largely limited to comparing descriptively the pharmacokinetic (PK) profiles by antidrug antibodies (ADA) status or testing the significance of ADA as a covariate in a population PK setting, similar to the practice for small-molecule drugs in investigating the effect of an intrinsic/extrinsic factor on the drug disposition. There is a need for a mAb disposition framework that captures the dynamics of ADA formation and drug's interactions with the ADA and target as parts of the drug distribution and elimination. Here we describe such a framework and examine it against the PK, ADA, and clinical response data from a phase 3 trial in patients treated with adalimumab. The proposed framework offered a generalized understanding of how the dose, target affinity, and drug/ADA analyte forms affects the manifestation of ADA response with regard to its detections and alterations of drug disposition and effectiveness. Furthermore, as an example, its utility for dose considerations was demonstrated through predicting for late-stage trials of a PCSK9 inhibitor in terms of development in ADA incidence and titers, and consequences on the drug disposition, interaction with target, and downstream lowering effect on LDL-C.

ACE mRNA (Additional Chimeric Element incorporated IVT mRNA) for Enhancing Protein Expression by Modulating Immunogenicity

The development of in vitro transcribed mRNA (IVT mRNA)-based therapeutics/vaccines depends on the management of IVT mRNA immunogenicity. IVT mRNA, which is used for intracellular protein translation, often triggers unwanted immune responses, interfering with protein expression and leading to reduced therapeutic efficacy. Currently, the predominant approach for mitigating immune responses involves the incorporation of costly chemically modified nucleotides like pseudouridine (Ψ) or N1-methylpseudouridine (m1Ψ) into IVT mRNA, raising concerns about expense and the potential misincorporation of amino acids into chemically modified codon sequences. Here, an Additional Chimeric Element incorporated mRNA (ACE mRNA), a novel approach incorporating two segments within a single IVT mRNA structure, is introduced. The first segment retains conventional IVT mRNA components prepared with unmodified nucleotides, while the second, comprised of RNA/DNA chimeric elements, aims to modulate immunogenicity. Notably, ACE mRNA demonstrates a noteworthy reduction in immunogenicity of unmodified IVT mRNA, concurrently demonstrating enhanced protein expression efficiency. The reduced immune responses are based on the ability of RNA/DNA chimeric elements to restrict retinoic acid-inducible gene I (RIG-I) and stimulator of interferon genes (STING)-mediated immune activation. The developed ACE mRNA shows great potential in modulating the immunogenicity of IVT mRNA without the need for chemically modified nucleotides, thereby advancing the safety and efficacy of mRNA-based therapeutics/vaccines.

Endotoxin reduction from biotech silk material inhibits the production of anti-silk antibodies in mice

Eliminating endotoxins is a common problem in the development of biotechnologically produced pharmaceuticals or biomaterials. Residual endotoxins in the final sample may hamper the properties of the product or induce severe adverse effects. Developing an effective downstream purification protocol that ensures a lack of minimal endotoxin content in the final product can be a challenging task. In our previous studies, we developed nanospheres produced from bioengineered silks. Despite their good overall biocompatibility, in vivo characterization of spheres showed mild activation of the immune system (mainly in terms of anti-silk antibody production). Herein, we examined, if the endotoxins delivered with the silk spheres might have contributed to activating the adaptive immune response. We investigated various commercially available methods for endotoxin removal that can be applied as an extra step in downstream endotoxin removal from MS1-type silk proteins. We selected a method that allowed for a 10-fold reduction of endotoxin content in soluble silk and 2-fold in the final product (silk spheres). The reduced level of endotoxins improved the biocompatibility of the silk spheres as these particles induced negligible titers of anti-silk antibodies in an in vivo immune study. Since endotoxins can enhance life-threatening immune responses, it is crucial to optimize the method of their removal before clinical use not only of silk-based products but also of other biomolecules produced biotechnologically.

Rationale for Japanese encephalitis vaccination in short-term travellers to endemic areas

Although the Japanese encephalitis (JE) vaccine is typically strongly recommended for long-term high-risk travellers, some cases of JE infections have been reported amongst short-term travellers with seemingly low risk. This article underscores the advantages and reasoning behind JE vaccination for this particular group of travellers.

A randomized, double-blinded Phase 3 study to demonstrate lot-to-lot consistency and to confirm immunogenicity and safety of the live-attenuated chikungunya virus vaccine candidate VLA1553 in healthy adults†

BACKGROUND

The global spread of the chikungunya virus (CHIKV) increases the exposure risk for individuals travelling to or living in endemic areas. This Phase 3 study was designed to demonstrate manufacturing consistency between three lots of the single shot live-attenuated CHIKV vaccine VLA1553, and to confirm the promising immunogenicity and safety data obtained in previous trials.

METHODS

This randomized, double-blinded, lot-to-lot consistency, Phase 3 study, assessed immunogenicity and safety of VLA1553 in 408 healthy adults (18-45 years) in 12 sites across the USA. The primary endpoint was a comparison of the geometric mean titre (GMT) ratios of CHIKV-specific neutralizing antibodies between three VLA1553 lots at 28 days post-vaccination. Secondary endpoints included immunogenicity and safety over 6 months post-vaccination.

RESULTS

GMTs were comparable between the lots meeting the acceptance criteria for equivalence. The average GMT (measured by 50% CHIKV micro plaque neutralization test; μPRNT50) peaked with 2643 at 28 days post-vaccination and decreased to 709 at 6 months post-vaccination. An excellent seroresponse rate (defined as μPRNT50 titre ≥ 150 considered protective) was achieved in 97.8% of participants at 28 days post-vaccination and still persisted in 96% at 6 months after vaccination. Upon VLA1553 immunization, 72.5% of participants experienced adverse events (AEs), without significant differences between lots (related solicited systemic AE: 53.9% of participants; related solicited local AE: 19.4%). Overall, AEs were mostly mild or moderate and resolved without sequela, usually within 3 days. With 3.9% of participants experiencing severe AEs, 2.7% were classified as related, whereas none of the six reported serious adverse events was related to the administration of VLA1553.

CONCLUSIONS

All three lots of VLA1553 recapitulated the safety and immunogenicity profiles of a preceding Phase 3 study, fulfilling pre-defined consistency requirements. These results highlight the manufacturability of VLA1553, a promising vaccine for the prevention of CHIKV disease for those living in or travelling to endemic areas.

Long-term immunogenicity and safety of heterologous boosting with a SARS-CoV-2 mRNA vaccine (SYS6006) in Chinese participants who had received two or three doses of inactivated vaccine

The emerging new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) needs booster vaccination. We evaluated the long-term safety and immunogenicity of heterologous boosting with a SARS-CoV-2 messenger RNA vaccine SYS6006. A total of 1000 participants aged 18 years or more who had received two (Group A) or three (Group B) doses of SARS-CoV-2 inactivated vaccine were enrolled and vaccinated with one dose of SYS6006 which was designed based on the prototype spike protein and introduced mutation sites. Adverse events (AEs) through 30 days and serious AEs during the study were collected. Live-virus and pseudovirus neutralizing antibody (Nab), binding antibody (immunoglobulin G [IgG]) and cellular immunity were tested through 180 days. Solicited all, injection-site and systemic AEs were reported by 618 (61.8%), 498 (49.8%), and 386 (38.6%) participants, respectively. Most AEs were grade 1. The two groups had similar safety profile. No vaccination-related SAEs were reported. Robust wild-type (WT) live-virus Nab response was elicited with peak geometric mean titers (GMTs) of 3769.5 (Group A) and 5994.7 (Group B) on day 14, corresponding to 1602.5- and 290.8-fold increase versus baseline, respectively. The BA.5 live-virus Nab GMTs were 87.7 (Group A) and 93.2 (Group B) on day 14. All participants seroconverted for WT live-virus Nab. Robust pseudovirus Nab and IgG responses to wild type and BA.5 were also elicited. ELISpot assay showed robust cellular immune response, which was not obviously affected by virus variation. In conclusion, SYS6006 heterologous boosting demonstrated long-term good safety and immunogenicity in participants who had received two or three doses of SARS-CoV-2 inactivated vaccine.

Boosting Vaccine Response in Autoimmune Rheumatic Disease Patients With Inadequate Seroconversion: An Analysis of the Immunogenicity of Vector-Based and Inactivated Vaccines

BACKGROUND

An additional dose of COVID-19 vaccine is being offered to vaccinated people, especially those immunocompromised. The most widely available vaccines in India are the adenoviral vector-based AZD1222 (ChAdOx1 nCoV-19) and the heat-inactivated (BBV152). This study investigated the efficacy of both vaccines in patients with autoimmune rheumatic diseases (AIRD).

OBJECTIVES

 To compare final anti-SARS-CoV-2 antibody titers, neutralization of pseudovirions by these antibodies, and T cell responses between patients of AIRD who had received the third dose of AZD1222 and BBV152 vaccines.

METHODS

Patients with stable AIRD who had completed two doses of COVID-19 vaccination but had a suboptimal response (anti-receptor binding domain (RBD) antibody<212) were randomized (1:1) to receive either AZD1222 or BBV152 as a booster dose. Patients with previous hybrid immunity or those who developed COVID-19 during the trial were excluded. Antibody titers, neutralization of Wuhan and Omicron pseudovirions, and interferon release by T cells (enzyme-linked immunosorbent spot (ELISpot)) in response to the Spike antigen were measured four weeks after this booster dose.

RESULTS

146 were screened, 91 were randomized, and 67 were analyzed per protocol. The third dose improved antibody titers (p<0.001), neutralization of the Wuhan strain (p<0.001), and T cell interferon release (p<0.001) but not neutralization of the Omicron strain (p=0.24). Antibody titers were higher (p<0.005) after ADZ1222 boost (2,414 IU (interquartile range (IQR): 330-10,315)) than BBV1222 (347.7 IU (0.4-973)). Neutralization of the Wuhan stain was better (AZD1222: 76.6%(23.0-95.45) versus BBV152 (32.7% (0-78.9), p=0.03 by ANCOVA). Neutralization of Omicron (0 (0-28.4) vs 0 (0-4.8)) and T cell interferon release (57.0 IU (23.5-95) vs 50.5 IU (13.2-139)) were similar.

CONCLUSION

The third dose improved all parameters of immunogenicity in AIRD patients with previous inadequate responses except Omicron neutralization. The vector-based vaccine exhibits notable efficacy, particularly in antibody titers and neutralizing the Wuhan strain.

TRIAL REGISTRATION

CTRI/2021/12/038928.

A subunit vaccine based on Brucella melitensis rBP26 induces Th1 immune responses and M1 macrophage activation

Brucellosis is a global zoonotic infection caused by Brucella bacteria, which poses a significant burden on society. While transmission prevention is currently the most effective method, the absence of a licenced vaccine for humans necessitates the urgent development of a safe and effective vaccine. Recombinant protein-based subunit vaccines are considered promising options, and in this study, the Brucella BP26 protein is expressed using prokaryotic expression systems. The immune responses are evaluated using the well-established adjuvant CpG-ODN. The results demonstrate that rBP26 supplemented with a CpG adjuvant induces M1 macrophage polarization and stimulates cellular immune responses mediated by Th1 cells and CD8 + T cells. Additionally, it generates high levels of rBP26-specific antibodies in immunized mice. Furthermore, rBP26 immunization activates, proliferates, and produces cytokines in T lymphocytes while also maintaining immune memory for an extended period of time. These findings shed light on the potential biological function of rBP26, which is crucial for understanding brucellosis pathogenesis. Moreover, rBP26 holds promise as an effective subunit vaccine candidate for use in endemic areas.