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Background Risks to mother and fetus following Ebola virus infection are very high. Evaluation of safety and immunogenicity of non-replicating Ebola vaccine candidates is a priority for use in pregnant women. This is the protocol for a randomized, open-label, single-center phase 3 clinical trial of the safety, reactogenicity, and immunogenicity of the 2-dose Ebola vaccine regimen in healthy adult pregnant women. This 2-dose regimen has been shown to be safe, judged effective, and approved in non-pregnant populations. Methods A total of 2000 adult (≥ 18 years of age) pregnant women will be enrolled from antenatal care facilities in Western Rwanda and randomized (1:1) to receive the 2-dose Ebola vaccine regimen (Ad26.ZEBOV, MVA-BN-Filo (group A)) or control (unvaccinated pregnant women (group B)). The primary objectives are to (1) assess adverse maternal/fetal outcomes in randomized pregnant women up to 1.5 months after delivery and (2) assess adverse neonatal/infant outcomes in neonates/infants born to randomized women up to 3.5 months after birth. The frequency and relatedness of all serious adverse events in women and newborns from randomization or birth, respectively, until study end will be reported. The reactogenicity and unsolicited adverse events of the 2-dose Ebola vaccine regimen in all vaccinated pregnant women (group A) will be reported. We will also assess the immunogenicity of the 2-dose Ebola vaccine regimen in 150 pregnant women who are anticipated to receive both vaccine doses within the course of their pregnancy (a subset of the 1000 pregnant vaccinated women from group A) compared to 150 non-pregnant women vaccinated after delivery (a subset of group B). The persistence of maternal antibodies in 75 infants born to women from the group A subset will be assessed. Exploratory analyses include assessment of acceptability of the 2-dose Ebola vaccine regimen among group A and assessment of maternal antibodies in breast milk in 50 women from group A and 10 controls (women from group B prior to vaccination). Discussion This study is intended to support a label variation to relax restrictions on use in pregnant women, a vulnerable population with high medical need. Trial registration Clinicaltrials.gov NCT04556526 . September 21, 2020.

IntroductionEbola virus disease (EVD) continues to be a significant public health problem in sub-Saharan Africa, especially in the Democratic Republic of the Congo (DRC). Large-scale vaccination during outbreaks may reduce virus transmission. We established a large population-based clinical trial of a heterologous, two-dose prophylactic vaccine during an outbreak in eastern DRC to determine vaccine effectiveness.Methods and analysisThis open-label, non-randomised, population-based trial enrolled eligible adults and children aged 1 year and above. Participants were offered the two-dose candidate EVD vaccine regimen VAC52150 (Ad26.ZEBOV, Modified Vaccinia Ankara (MVA)-BN-Filo), with the doses being given 56 days apart. After vaccination, serious adverse events (SAEs) were passively recorded until 1 month post dose 2. 1000 safety subset participants were telephoned at 1 month post dose 2 to collect SAEs. 500 pregnancy subset participants were contacted to collect SAEs at D7 and D21 post dose 1 and at D7, 1 month, 3 months and 6 months post dose 2, unless delivery was before these time points. The first 100 infants born to these women were given a clinical examination 3 months post delivery. Due to COVID-19 and temporary suspension of dose 2 vaccinations, at least 50 paediatric and 50 adult participants were enrolled into an immunogenicity subset to examine immune responses following a delayed second dose. Samples collected predose 2 and at 21 days post dose 2 will be tested using the Ebola viruses glycoprotein Filovirus Animal Non-Clinical Group ELISA. For qualitative research, in-depth interviews and focus group discussions were being conducted with participants or parents/care providers of paediatric participants.Ethics and disseminationApproved by Comité National d’Ethique et de la Santé du Ministère de la santé de RDC, Comité d'Ethique de l'Ecole de Santé Publique de l’Université de Kinshasa, the LSHTM Ethics Committee and the MSF Ethics Review Board. Findings will be presented to stakeholders and conferences. Study data will be made available for open access.Trial registration numberNCT04152486.

Two phase 3 clinical studies were conducted in the USA to bridge across different Ad26.ZEBOV manufacturing processes and sites, and to evaluate the immunogenicity of different dose levels of Ad26.ZEBOV and MVA-BN-Filo. Study 1 evaluated the immunological equivalence of three batches of Ad26.ZEBOV administered as dose 1, followed by one batch of MVA-BN-Filo as dose 2. In Study 2, immunogenic non-inferiority of intermediate (Ad26.ZEBOV: 2 × 1010 viral particles [vp], MVA-BN-Filo: 5 × 107 infectious units [Inf.U]) and low (8 × 109 vp, 5 × 107 Inf.U) doses of Ad26.ZEBOV and MVA-BN-Filo were evaluated against the full clinical dose (5 × 1010 vp, 1 × 108 Inf.U). In Study 1, equivalence was demonstrated for two of three batch comparisons post-dose 1 and all three batches after the full regimen. Study 2 demonstrated a dose-dependent response; however, non-inferiority against the full clinical dose was not met. All regimens were well tolerated and immune responses were observed in all participants, regardless of manufacturing process or dose. Consistency of immunogenicity of different Ad26.ZEBOV batches was demonstrated and a dose-dependent response was observed after Ad26.ZEBOV, MVA-BN-Filo vaccination. ClinicalTrials.gov identifiers: NCT02543268; NCT02543567.

It has been proven challenging to conduct traditional efficacy trials for Ebola virus (EBOV) vaccines. In the absence of efficacy data, immunobridging is an approach to infer the likelihood of a vaccine protective effect, by translating vaccine immunogenicity in humans to a protective effect, using the relationship between vaccine immunogenicity and the desired outcome in a suitable animal model. We here propose to infer the protective effect of the Ad26.ZEBOV, MVA-BN-Filo vaccine regimen with an 8-week interval in humans by immunobridging. Immunogenicity and protective efficacy data were obtained for Ad26.ZEBOV and MVA-BN-Filo vaccine regimens using a fully lethal EBOV Kikwit challenge model in cynomolgus monkeys (nonhuman primates [NHP]). The association between EBOV neutralizing antibodies, glycoprotein (GP)-binding antibodies, and GP-reactive T cells and survival in NHP was assessed by logistic regression analysis. Binding antibodies against the EBOV surface GP were identified as the immune parameter with the strongest correlation to survival post EBOV challenge, and used to infer the predicted protective effect of the vaccine in humans using published data from phase I studies. The human vaccine-elicited EBOV GP-binding antibody levels are in a range associated with significant protection against mortality in NHP. Based on this immunobridging analysis, the EBOV GP-specific-binding antibody levels elicited by the Ad26.ZEBOV, MVA-BN-Filo vaccine regimen in humans will likely provide protection against EBOV disease.

The mechanisms regulating the outgrowth of neurites during development, as well as after injury, are key to the understanding of the wiring and functioning of the brain under normal and pathological conditions. The amyloid precursor protein (APP) is involved in the pathogenesis of Alzheimer's disease (AD). However, its physiological role in the central nervous system is not known. Many physical interactions between APP and intracellular signalling molecules have been described, but their functional relevance remains unclear. We show here that human APP and Drosophila APP‐Like (APPL) can induce postdevelopmental axonal arborization, which depends critically on a conserved motif in the C‐terminus and requires interaction with the Abelson (Abl) tyrosine kinase. Brain injury induces APPL upregulation in Drosophila neurons, correlating with increased post‐traumatic mortality in appl d mutant flies. Finally, we also found interactions between APP and the JNK stress kinase cascade. Our findings suggest a role for APP in axonal outgrowth after traumatic brain injury.

Without clinical efficacy data, vaccine protective effect may be extrapolated from animals to humans using an immunologic marker that correlates with protection in animals. This immunobridging approach was used for the two-dose Ebola vaccine regimen Ad26.ZEBOV, MVA-BN-Filo. Ebola virus (EBOV) glycoprotein binding antibody data obtained from 764 vaccinated healthy adults in five clinical studies (NCT02416453, NCT02564523, NCT02509494, NCT02543567, NCT02543268) were used to calculate mean predicted survival probability (with preplanned 95% confidence interval [CI]). We used a logistic regression model based on EBOV glycoprotein binding antibody responses in vaccinated non-human primates (NHPs) and NHP survival after EBOV challenge. While the protective effect of the vaccine regimen in humans can be inferred in this fashion, the extrapolated survival probability cannot be directly translated into vaccine efficacy. The primary immunobridging analysis evaluated the lower limit of the CI against predefined success criterion of 20% and passed with mean predicted survival probability of 53.4% (95% CI: 36.7–67.4).

The adjuvanted hepatitis B vaccine, HB-AS04, elicits more rapid and persistent protective antibody concentrations than double doses of conventional recombinant vaccines in patients with renal insufficiency. We compared the immunogenicity, reactogenicity, and safety of the AS02(V)-adjuvanted hepatitis B vaccine HB-AS02 with that of HB-AS04. In this phase III, open, randomized study, 151 hepatitis B vaccine-naïve pre-dialysis, peritoneal dialysis, and hemodialysis patients aged 15 years and older received three doses of HB-AS02 at 0, 1, and 6 months. Another 149 similar patients received four doses of HB-AS04 at 0, 1, 2, and 6 months, and all were followed up for 12 months. HB-AS02 elicited more rapid and persistent seroprotection than HB-AS04, with rates of 77 and 39%, respectively, 1 month after the second vaccine dose, and 94 and 79%, respectively, at 12 months. Superiority of HB-AS02 over HB-AS04 in anti-hepatitis B geometric mean concentrations was found at all time points. HB-AS02 was more reactogenic than HB-AS04, but adverse events were mainly transient, of mild to moderate intensity with no reportable vaccine-related serious events. We conclude that a three-dose primary course of HB-AS02 induced more rapid, enhanced, and persistent protection in patients with renal insufficiency than the licensed four-dose primary schedule of HB-AS04. This adjuvanted vaccine affords greater protection with reduced need for booster doses in patients at high risk of hepatitis B infection.

The adjuvanted hepatitis B vaccine, HB-AS04, elicits more rapid and persistent protective antibody concentrations than double doses of conventional recombinant vaccines in patients with renal insufficiency. We compared the immunogenicity, reactogenicity, and safety of the AS02V-adjuvanted hepatitis B vaccine HB-AS02 with that of HB-AS04. In this phase III, open, randomized study, 151 hepatitis B vaccine-naïve pre-dialysis, peritoneal dialysis, and hemodialysis patients aged 15 years and older received three doses of HB-AS02 at 0, 1, and 6 months. Another 149 similar patients received four doses of HB-AS04 at 0, 1, 2, and 6 months, and all were followed up for 12 months. HB-AS02 elicited more rapid and persistent seroprotection than HB-AS04, with rates of 77 and 39%, respectively, 1 month after the second vaccine dose, and 94 and 79%, respectively, at 12 months. Superiority of HB-AS02 over HB-AS04 in anti-hepatitis B geometric mean concentrations was found at all time points. HB-AS02 was more reactogenic than HB-AS04, but adverse events were mainly transient, of mild to moderate intensity with no reportable vaccine-related serious events. We conclude that a three-dose primary course of HB-AS02 induced more rapid, enhanced, and persistent protection in patients with renal insufficiency than the licensed four-dose primary schedule of HB-AS04. This adjuvanted vaccine affords greater protection with reduced need for booster doses in patients at high risk of hepatitis B infection.

The precise number and pattern of axonal connections generated during brain development regulates animal behavior. Therefore, understanding how developmental signals interact to regulate axonal extension and retraction to achieve precise neuronal connectivity is a fundamental goal of neurobiology. We investigated this question in the developing adult brain of Drosophila and find that it is regulated by crosstalk between Wnt, fibroblast growth factor (FGF) receptor, and Jun N-terminal kinase (JNK) signaling, but independent of neuronal activity. The Rac1 GTPase integrates a Wnt-Frizzled-Disheveled axon-stabilizing signal and a Branchless (FGF)-Breathless (FGF receptor) axon-retracting signal to modulate JNK activity. JNK activity is necessary and sufficient for axon extension, whereas the antagonistic Wnt and FGF signals act to balance the extension and retraction required for the generation of the precise wiring pattern.

The behaviour of all animals is governed by the connectivity of neural circuits in the brain. Neurodevelopmental and neurodegenerative diseases, as well as traumatic injuries to the nervous system, can alter or disrupt the normal connectivity of the brain and result in disability. In this review, we highlight the contributions of the genetic model organism Drosophila melanogaster to our understanding of neural connectivity in health and disease. In this context we also discuss the research areas in which we believe the fruitfly is likely to be a useful model system in the future.