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The Jenner Institute is based within the Nuffield Department of Medicine, University of Oxford, and operates out of the Old Road Campus Research Building, in Headington, Oxford.
Rabies glycoprotein engineering for improved stability and expression.
Current rabies vaccines require multiple doses and are relatively expensive, limiting their accessibility. Novel low-cost vaccines capable of inducing a protective antibody response against the rabies virus glycoprotein (RVG) are therefore desirable. Structure-guided engineering of the antigen may enhance its qualitative or quantitative immunogenicity, as may transgene cassette optimisation in the case of vectored vaccines. We investigated the potential of these approaches for the design of improved rabies vaccines. We evaluated twelve candidate cassette designs. While codon optimisation enhanced expression in vitro, it did not translate into improved immunogenicity. Co-expression or RVG with rabies matrix protein (RVM) did not detectably affect expression or immunogenicity. Inserting a C-terminal trimerisation domain was detrimental to expression in vitro and did not improve immunogenicity compared to the wild-type comparator. We screened 72 mutant constructs for in vitro expression and pre-fusion stabilisation. Several mutants enhanced expression and/or pre-fusion stability at low pH. Combination of the previously reported H270P mutation with the H419L substitution achieved enhanced stability. An L271Q + H419L double mutant achieved the greatest positive effect upon expression. Neither of double mutants improved immunogenicity compared to wild-type RVG when tested using an mRNA vaccine platform. These mutant constructs may be of value for protein subunit vaccines, but full length wild-type RVG may be sufficiently conformationally stable and well-expressed for optimal immunogenicity of adenovirus and mRNA vaccines in mice.
Synergistic blockade of TIGIT and PD-L1 increases type-1 inflammation and improves parasite control during murine blood-stage Plasmodium yoelii non-lethal infection
ABSTRACT Pro-inflammatory immune responses are rapidly suppressed during blood-stage malaria but the molecular mechanisms driving this regulation are still incompletely understood. In this study, we show that the co-inhibitory receptors TIGIT and PD-1 are upregulated and co-expressed by antigen-specific CD4 + T cells (ovalbumin-specific OT-II cells) during non-lethal Plasmodium yoelii expressing ovalbumin ( Py NL -OVA ) blood-stage infection. Synergistic blockade of TIGIT and PD-L1, but not individual blockade of each receptor, during the early stages of infection significantly improved parasite control during the peak stages (days 10–15) of infection. Mechanistically, this protection was correlated with significantly increased plasma levels of IFN-γ, TNF, and IL-2, and an increase in the frequencies of IFN-γ-producing antigen-specific T-bet + CD4 + T cells (OT-II cells), but not antigen-specific CD8 + T cells (OT-I cells), along with expansion of the splenic red pulp and monocyte-derived macrophage populations. Collectively, our study identifies a novel role for TIGIT in combination with the PD1-PD-L1 axis in regulating specific components of the pro-inflammatory immune response and restricting parasite control during the acute stages of blood-stage Py NL infection.
Comparative performance of the InBios SCoV-2 DetectTM IgG ELISA and the in-house KWTRP ELISA in detecting SARS-CoV-2 spike IgG antibodies in Kenyan populations
Background The InBios SCoV-2 Detect™ IgG ELISA (InBios) and the in-house KWTRP ELISA (KWTRP) have both been used in the estimation of SARS-CoV-2 seroprevalence in Kenya. Whereas the latter has been validated extensively using local samples, the former has not. Such validation is important for informing the comparability of data across the sites and populations where seroprevalence has been reported. Methods We compared the assays directly using pre-pandemic serum/plasma collected in 2018 from 454 blood donors and 173 malaria cross-sectional survey participants, designated gold standard negatives. As gold standard SARS-CoV-2 positive samples: we assayed serum/plasma from 159 SARS-CoV-2 PCR-positive patients and 166 vaccination-confirmed participants. Results The overall agreement on correctly classified samples was >0.87 for both assays. The overall specificity was 0.89 (95% CI, 0.87–0.91) for InBios and 0.99 (95% CI, 0.97–0.99) for KWTRP among the gold standard negative samples while the overall sensitivity was 0.97 (95% CI, 0.94–0.98) and 0.93 (95% CI, 0.90– 0.95) for InBios and KWTRP ELISAs respectively, among the gold standard positive samples. In all, the positive predictive value for InBios was 0.83 (95% CI, 0.79-0.87) and 0.98 (95% CI, 0.96-0.99) for KWTRP while the negative predictive value was 0.98 (95% CI, 0.97- 0.99) and 0.97 (95% CI, 0.95-0.98) for InBios and KWTRP respectively. Conclusions Overall, both assays showed sufficient sensitivity and specificity to estimate SARS-CoV-2 antibodies in different populations in Kenya.
Establishing laboratory reference ranges for haematological and biochemical blood parameters in adults and children in Kilifi, Kenya
Background Accurate laboratory reference ranges (RR) are essential for diagnosis and management of patients in routine clinical care and clinical trials. RRs vary between geographical location due to differences in population demographics and blood analysis equipment, so locally derived RRs are essential. Here we establish adult and paediatric RRs for a rural population in Kilifi, Kenya using clinical trial data from KEMRI-Wellcome Trust Research Programme (KWTRP). Methods Data from healthy, non-pregnant participants from six clinical trials conducted between 2016 and 2020 were used. Coulter ACT 5 Diff and Ilab Aries were used for haematological and biochemical analysis respectively. Quality control was undertaken daily prior to sample analysis. Derived RRs were compared with RRs from other African countries and further afield. All analyses were performed using R version 3.6.1 (Reference Intervals package). Results 2338 adults and 2054 children were included, 52% of adults and 51% of children were male, median adult age was 32.5 years. Haemoglobin range was lower in women compared to men (9.5–14.2g/dL and 11.5–16.6g/dL respectively), platelet upper limit of normal (ULN) was higher in women compared to men (397 x 103/μL vs 358 x 103/ μL). Biochemistry values were higher in men (ALT ULN 57 U/L in men and 35 U/L in women, creatinine ULN 113umol/L in men and 91umol/L in women). Paediatric RRs showed differences in multiple parameters depending on the age of the child. In both adults and children, many parameters in 2023 Kilifi RRs differed from those in other countries. There was however little difference between 2023 and 2017 Kilifi paediatric RRs. Conclusions This study provides RRs for adults and children in Kilifi, and the most extensive RRs available for much of East and Southern Africa. We show the need for locally derived reference ranges, highlighting differences between sex, age and geographical location.
Non-typhoidal Salmonella combination vaccines: clinical development plan and regulatory considerations.
Invasive non-typhoidal serovars of Salmonella enterica,S. Typhimurium and S. Enteritidis, (iNTS) are estimated to cause over 500,000 cases of disease leading to more than 79,000 deaths with a high case fatality ratio of 14.5 %. Most infections occur in infants and young children in LMICs in sub-Saharan Africa where host risk factors for iNTS disease such as malaria, malnutrition, HIV infection, and anemia are common. iNTS disease is observed from birth, with a peak incidence early in the second year of life, declining before the age of 3 years. The prevalence of multiple drug resistance of iNTS has increased markedly by decade, emphasizing the need for effective vaccines. A clinical development plan and regulatory pathway for licensure of iNTS vaccines has been shaped following the development of Preferred Product Characteristics and R&D Roadmap through a series of expert consultations. Several iNTS alone or combined with Typhoid Conjugate Vaccine platforms are in early clinical development. Encouraging safety and immunogenicity data have prompted developers and manufacturers to plan efficacy trials, aligned with regulatory expectations. It is critical to clearly communicate iNTS disease burden in endemic countries and to discuss complexities related to iNTS single component or combination vaccine clinical development with regulators. An essential component is the disease burden in infants less than 6 months of age, which will inform the optimal age of first vaccination (less than or from 6 months), compatibility across national expanded programme on immunization schedules, and whether a booster dose would be needed. Early regulatory guidance is essential to make informed regulatory decisions and to guide the clinical development plan and licensure pathway. Continued communication with public health stakeholders and end-user representatives will effectively contribute to better awareness and education about iNTS disease and protection afforded by vaccination.
Early mucosal responses following a randomised controlled human inhaled infection with attenuated Mycobacterium bovis BCG
Abstract The development of an effective vaccine against Mycobacterium tuberculosis is hampered by an incomplete understanding of immunoprotective mechanisms. We utilise an aerosol human challenge model using attenuated Mycobacterium bovis BCG, in BCG-naïve UK adults. The primary endpoint of this study (NCT03912207) was to characterise the early immune responses induced by aerosol BCG infection, the secondary endpoint was to identify immune markers associated with in-vitro protection. Blinded volunteers were randomised to inhale 1 × 107 CFU aerosolised BCG or 0.9% saline (20:6); and sequentially allocated to bronchoscopy at day 2 or 7 post-inhalation (10 BCG, 3 saline each timepoint). In the bronchoalveolar lavage post-aerosol BCG infection, there was an increase in frequency of eosinophils, neutrophils, NK cells and Donor-Unrestricted T cells at day 7, and the frequency of antigen presenting cells decreased at day 7 compared with day 2. The frequency of interferon-gamma+ BCG-specific CD4+ T cells increased in the BAL and peaked in the blood at day 7 post-BCG infection compared to day 2. BAL cells at day 2 and day 7 upregulated gene pathways related to phagocytosis, MHC-II antigen loading, T cell activation and proliferation. BCG’s lack of key virulence factors and its failure to induce granulomas, may mean the observed immune responses do not fully recapitulate Mycobacterium tuberculosis infection. However, human infection models can provide unique insights into early immune mechanisms, informing vaccine design for complex pathogens.
Nipah virus vaccines evaluated in pigs as a 'One Health' approach to protect public health.
Nipah virus (NiV) causes a severe neurological disease in humans. The first NiV outbreak, in Malaysia, involved pig-to-human transmission, that resulted in significant economic losses to the local pig industry. Despite the risk NiV poses to pig-dense regions, no licensed vaccines exist. This study therefore assessed three NiV vaccine candidates in pigs: (1) adjuvanted soluble NiV (s)G protein, (2) adjuvanted pre-fusion stabilised NiV (mcs)F protein, and (3) adenoviral vectored NiV G (ChAdOx1 NiV G). NiV sG induced the strongest neutralising antibody response, NiV mcsF induced antibodies best able to neutralise cell-cell fusion, whereas ChAdOx1 NiV G elicited CD8+ T-cell responses. Despite differences in immunogenicity, prime-boost immunisation with all candidates conferred a high degree of protection against NiV infection. Follow-up studies demonstrated longevity of immune responses and broadly comparable immune responses in Bangladeshi pigs under field conditions. These studies provide a platform for developing a NiV vaccine for pigs.
Repertoire, function, and structure of serological antibodies induced by the R21/Matrix-M malaria vaccine.
The World Health Organization (WHO) recently recommended the programmatic use of the R21/Matrix-M vaccine for Plasmodium falciparum malaria prevention in children living in malaria-endemic areas. To determine its effects on humoral immunity, we conducted a proteomic analysis of polyclonal IgG antibodies directed against the NANP tetrapeptide of the circumsporozoite protein (CSP), which comprises the vaccine's core immunogen. In 10 malaria-naïve adult volunteers, R21/Matrix-M induced polarized IgG anti-NANP repertoires, heavily skewed for IGHV3-30/3-33 genes bearing minimal somatic mutation, which remained static in composition following a controlled human malaria infection challenge. Notably, these vaccine-generated antibodies cross-reacted with another protective CSP epitope, the N-terminal junction region, despite its absence from the R21 construct. NANP-specific IGHV3-30/3-33 mAbs mined from polyclonal IgG repertoires blocked sporozoite invasion in vitro and prevented parasitemia in vivo. Overall, R21/Matrix-M elicits polarized, minimally mutated, polyclonal IgG responses that can target multiple protective CSP epitopes, offering molecular insight into the serological basis for its demonstrated efficacy against P. falciparum malaria.
Adenoviral vaccines—Infectious disease
Since the early 2000s, adenoviral vectors have been extensively used for the development of infectious disease vaccines. The first clinical vectors were derived from species C human adenovirus type 5 (HAdV-C5) and induced robust T cell and antibody responses against the encoded antigen. However, with widespread prevalence of HAdV-C5 in the human population, pre-existing immunity against the vector often adversely impacts vaccine immunogenicity. To circumvent this, rare human types and nonhuman types have been evaluated as vaccine vectors. Impressively, over 50 adenoviral vectored vaccines have been clinically evaluated against a wide range of pathogens, exploring different dosing regimens and delivery routes. In 2014, the first adenovirus-based vaccine was licensed, utilizing a vector derived from HAdV-D26, a rare human species D adenovirus with low seroprevalence. This adenoviral vector is delivered in a heterologous prime-boost regimen with Modified Vaccinia Ankara vector for prophylaxis against Ebola virus disease. Multiple clinical adenoviral vectored vaccines have since been granted marketing authorization. This success and subsequent widespread administration of adenoviral vectored vaccines is an additional source of antivector immunity, alongside that generated through natural adenovirus infection. This further drives the necessity to understand the mechanisms and impacts of antivector immunity, in addition to developing approaches to negate these. This chapter outlines the breadth of clinical adenoviral vectored vaccines developed against viral, parasitic and bacterial pathogens of humans, defining the clinical needs and associated challenges of such vaccines. The highlights and limitations of these adenoviral vectored vaccines are summarized, alongside vector delivery routes and dosing regimens, populations included during clinical evaluation, vaccine immunogenicity and efficacy outcomes, and the efforts to identify correlates of vaccine-induced protection.
MetE: a promising protective antigen for tuberculosis vaccine development
IntroductionTuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), remains a significant global health concern. The existing vaccine, Bacillus Calmette-Guérin (BCG), provides inconsistent protection, highlighting the pressing need for a more effective vaccine. We aimed to identify novel MTB antigens and assess their protective efficacy as TB vaccine candidates.MethodsUsing immunopeptidomics, we identified 64 and 80 unique mycobacterial antigens derived from BCG and MTB, respectively. We prioritised antigens based on HLA allele coverage through an immunoinformatics approach.ResultsThe candidates, hisD, metE, and mmpL12, delivered as DNA vaccines, were evaluated for efficacy in mice using the ex vivo Mycobacterial Growth Inhibition Assay (MGIA) and metE was identified as a promising candidate. In vivo murine MTB challenge experiments confirmed the protective efficacy conferred by metE when formulated as recombinant protein with AS01™ or AddaS03™ adjuvants, compared to the naïve group. The immunogenic profiles of metE formulated in the two different adjuvants differed, with metE-AS01™ inducing antigen-specific IFN-γ, TNF-α, IL-2, IL-17, IgG1 and IgG2a-c, while metE-AddaS03™ induced TNF-α, IL-2, IL-17, IL-4, IgM, IgG1, IgG2b.ConclusionOur findings highlight metE as a promising protective antigen for future TB vaccine development.
R21/Matrix-M malaria vaccine drives diverse immune responses in pre-exposed adults: insights from a phase IIb controlled human malaria infection trial.
INTRODUCTION: The recently licenced R21/Matrix-M vaccine induces a protective antibody response. In this study, we examined vaccine-induced responses in semi-immune adults in a controlled human malaria infection (CHMI) Phase IIb clinical trial. METHODS: Plasma and peripheral blood mononuclear cells from healthy adult volunteers living in coastal Kenya were analysed following vaccination with R21/Matrix-M (n = 19) and CHMI challenge with Plasmodium falciparum (PfSPZ NF54) sporozoites (n = 17). Humoral immunity was evaluated by quantifying antigen specific antibody subtypes and subclasses via ELISA, alongside functional antibody properties including avidity and complement fixation elicited by vaccination and challenge. Antigen-specific memory B cells were characterised using FluoroSpot assays to detect concurrent secretion of multiple antibody isotypes and the frequency and phenotypes of circulating Tfh (cTfh) cells were assessed using multiparametric flow cytometry. RESULTS: Vaccination increased antibody titres across IgA, IgM, and IgG isotypes and IgG1 and IgG3 subclasses but not IgG2 or IgG4 subclasses, targeting different vaccine antigens (full-length R21, NANP, and C-terminus), indicating a broad and heterogeneous response. The responses were maintained over time and, importantly, they demonstrated complement-fixing capabilities. IgG+ and IgA+ antigen-specific memory B cells were boosted but were short-lived for IgA. We observed an increase in total CXCR5+/PD1+ cTfh cells following vaccination and challenge with the predominant Th2/Th17 population. DISCUSSION: We provide insights into the diverse immune responses induced by R21/Matrix-M vaccination and their potential contribution to protection against malaria. These findings highlight the potential of the R21/Matrix-M vaccination and protection in adults with varying levels of prior malaria exposure.
Vaccine-induced responses to R21/Matrix-M - an analysis of samples from a phase 1b age de-escalation, dose-escalation trial.
IntroductionThe pre-erythrocytic malaria vaccine R21 vaccine adjuvanted with Matrix-M reported good efficacy (75%) in an ongoing phase 3 trial and was recommended World Health Organization for use in children 5-36 months. Vaccine-induced antibodies against NANP are associated with protection, however, various factors such as age, pre-existing immunity, and vaccine dose have been shown to influence vaccine responses.MethodsSamples from adults (n =18), children (n = 17), and infants (n = 51) vaccinated with R21/Matrix-M in a phase I trial were assayed for vaccine-specific antibody responses. We measured antibodies (quantity) by MSD and ELISA; and function (quality) by complement (C1q) fixation assay, inhibition of sporozoite invasion (ISI) assay, and avidity assay. Pre-existing malaria antibody exposure was assessed using an anti-3D7 Plasmodium falciparum crude parasite lysate ELISA.ResultsVaccine-induced CSP antibodies (against full-length R21, NANP, and C terminus), exhibited complement fixation and inhibition of sporozoites. These were significantly lower in adults compared to children and infants. Additionally, children had a higher rate of decay of vaccine-induced antibodies compared to adults 2 years post-vaccination. Furthermore, a higher Matrix-M adjuvant dose resulted in significantly higher C1q fixation, and ISI than the low adjuvant dose in infants. Importantly, functional measures ISI and C1q-fixation were positively associated with the vaccine-induced antibodies overall, but avidity was not. Interestingly, in adults, previous malaria exposure was negatively associated with ISI but positively correlated with avidity and C1q fixation. At baseline, all the study participants were seropositive for anti-HBsAg IgG above the WHO-required protective threshold of 10 mIU/mL, and titers significantly increased post-vaccination.DiscussionR21/Matrix-M was immunogenic across all age groups, with age and vaccine dose significantly affecting antibody magnitude and function. These findings emphasize the importance of evaluating the right adjuvant and vaccine dose for clinical development progression. This could thus inform the development of next-generation malaria vaccines. However, additional crucial factors need further exploration.
Validity of Clinical Severity Scores for Respiratory Syncytial Virus: A Systematic Review.
BackgroundRespiratory syncytial virus (RSV) is a widespread respiratory pathogen, and RSV-related acute lower respiratory tract infections are the most common cause of respiratory hospitalization in children <2 years of age. Over the last 2 decades, a number of severity scores have been proposed to quantify disease severity for RSV in children, yet there remains no overall consensus on the most clinically useful score.MethodsWe conducted a systematic review of English-language publications in peer-reviewed journals published since January 2000 assessing the validity of severity scores for children (≤24 months of age) with RSV and/or bronchiolitis, and identified the most promising scores. For included articles, (1) validity data were extracted, (2) quality of reporting was assessed using the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis checklist (TRIPOD), and (3) quality was assessed using the Prediction Model Risk Of Bias Assessment Tool (PROBAST). To guide the assessment of the validity data, standardized cutoffs were employed, and an explicit definition of what we required to determine a score was sufficiently validated.ResultsOur searches identified 8541 results, of which 1779 were excluded as duplicates. After title and abstract screening, 6670 references were excluded. Following full-text screening and snowballing, 32 articles, including 31 scores, were included. The most frequently assessed scores were the modified Tal score and the Wang Bronchiolitis Severity Score; none of the scores were found to be sufficiently validated according to our definition. The reporting and/or design of all the included studies was poor. The best validated score was the Bronchiolitis Score of Sant Joan de Déu, and a number of other promising scores were identified.ConclusionsNo scores were found to be sufficiently validated. Further work is warranted to validate the existing scores, ideally in much larger datasets.