Pump-Priming Project Awards - Round 2 Awardees

Dr Annette Erhart

Clinical Epidemiologist
MRC Unit The Gambia at LSHTM (The Gambia)

Collaborators:
Professor Martin Antonio, WHO Collaborating Centre for New Vaccines Surveillance, MRC Unit The Gambia at LSHTM (The Gambia)

Dr Thushan de Silva, Vaccines and Immunity Theme, MRC Unit The Gambia at LSHTM (The Gambia)

Dr Abdul Karim Sesay, Laboratory Service, MRC Unit The Gambia at LSHTM, (The Gambia)

Dr Claire Turner, University of Sheffield (UK)

Professor Pierre Smeesters, Université libre de Bruxelles (ULB) (Belgium)

Summary

Group A streptococcus (GAS) causes a massive burden of disease (>500,000 deaths per year), mainly in low- and middle-income countries (LMICs) where Rheumatic Heart Disease (RHD) causes >34 million cases and > 350,000 deaths per year. In May 2018, the WHO passed a resolution on RHD stressing the urgent need to improve prevention strategies, including the development of an effective vaccine. The most advanced multivalent M protein-based vaccine, currently in early clinical development is based on GAS strains found mainly in Europe and USA. In Africa and according to limited information, GAS infections seem to have a much higher genetic diversity of than in high income countries, suggesting that the efficacy of the current 30-valent vaccine may be sub-optimal. However, a recent study in Mali indicated cross-protection between vaccine and non-vaccine serotypes, with a higher-than-expected potential coverage. In order to further inform potential vaccine coverage in Africa, additional information on local GAS strains is urgently needed. This project aims at generating pioneering data on the molecular epidemiology of GAS in West Africa, and at initiating GAS genomic surveillance. Two hundred clinical GAS isolates stored at the MRC Unit The Gambia (MRCG) and 100 prospectively collected samples in Senegal and Burkina Faso will be analysed using whole genome sequencing at the MRCG.  Results will provide invaluable data to further inform current GAS vaccine development, to monitor antimicrobial resistance and to set the scene for upcoming vaccine trials in Africa.

Project outcomes

This one-year pilot study funded by the BactiVac Network has achieved its main objective of characterizing the molecular epidemiology of GAS strains and initiate GAS genomic surveillance in West Africa. Indeed, through existing regional networks funded by WHO (Reference Laboratory (RL) for Invasive Bacterial Diseases (IBD)) or EDTCP (WANETAM) we could initiate the prospective collection of GAS clinical samples, respectively in Senegal (Hopital Albert Royer, Dakar) and Burkina Faso (Centre Muraz, Bobo Dioulasso).

The GAS prevalence among prospectively collected samples was lower than expected (respectively 6% and 12% in Senegal and Burkina versus 20% expected) and this could unfortunately not be compensated by increasing the recruitment of patients given the short timelines. Therefore, 45 GAS isolates were collected, including 31 in Burkina and 14 in Senegal and, together with 306 retrospective GAS isolates from The Gambia (MRCG Biobank; total = 341), were subjected to analysis using by standard microbiology methods and Whole Genome Sequencing using Illumina MiSeq.

A total of 177 GAS isolates, including a majority of wound- (36%), oropharyngeal carriage- (21%) and blood samples (18%), were successfully sequenced. A total of 65 different emm types were identified and some isolates carried new sub-types which will be submitted to the CDC database. No dominant emm type was found, the most common being emm147 (4.5%) followed by emm44 and emm95 (totalling 4%). Interestingly, emm1 the most dominant emm type found in high income countries (HICs) was not found.

Multi-locus sequence typing (MLST) identified 86 different sequence types (STs) some of which represented new STs. The phylogenetic analysis of the first 70 complete genomes showed clustering of isolates by genotype.

All 177 isolates were tested for the presence of antimicrobial resistance genes using abricate software with the NCBI database. Several antimicrobial resistance genes were identified (Imrc, tets, tet (L), tetM, dfrK, efrA, DFRe and dfrg) and analysis is still ongoing.

Similarly, work is ongoing by a Gambian junior scientist further supported by MRCG to identify virulence factors and to evaluate theoretical vaccine coverage.

Together with other PIs working on GAS at the MRCG we recently created a GAS Study Group to join forces in establishing a regional library of reference GAS isolates and genomic sequences from The Gambia and across West Africa. Moreover, with the experience and contacts acquired during the prospective study with Burkina and Senegal, we plan to further collaborate with the WHO GAS Vaccine R&D Working Group as well as other WHO stakeholders (EPI-, Maternal & Child Health) to extend the scope of work of the existing WHO regional networks (ie, RL for IBD and -Collaborating Centre for New Vaccines Surveillance) to GAS genomic surveillance.

Such data are crucially needed to fill the current knowledge gap on molecular epidemiology of GAS strains in West Africa, inform the development of an effective GAS vaccine, and monitor the GAS population structure and transmission dynamics after the rollout of a vaccine.

Dr Rowena Mitchell (Hoare)

Senior Research Fellow
Institute of Aquaculture University of Stirling (UK)

Collaborators:
Professor Alexandra Adams, Institute of Aquaculture, University of Stirling (UK)

Dr Khalid Shahin, Institute of Aquaculture, University of Stirling (UK)

Dr Matthijs Metselaar, Benchmark Animal Health (UK)

Dr Kim Thompson, Moredun Research Institute (UK)

Dr Thao Ngo, Biotechnology Center of Ho Chi Minh City (Vietnam)

Summary

The majority of fish vaccines are multivalent oil-adjuvanted and given by injection. While they provide good protection against bacterial and viral pathogens, they have some drawbacks such as side effects and can only be delivered by injection. Mucosal vaccination of fish - by immersion and oral (in-feed) routes - has many benefits over injection: cost of application, mass vaccination of juveniles, less handling stress leads to less side effects and infections. At present, a limited number of mucosal vaccines are available for fish, primarily due to them being less effective than injection vaccines with shorter duration of immunity. The benefits of application of vaccine to fish by immersion or oral routes are numerous; ease of application being the foremost especially in less developed countries where expensive vaccination machines are not feasible for farmers. Many fish farmers in LMIC countries would benefit from immersion and oral vaccines that can protect their stocks for the duration of production. Development and optimisation of mucosal vaccines is essential to provide protection of aquaculture species worldwide and contribute to reducing the use of antibiotics and thereby antibiotic resistance. This project will modify an existing monovalent vaccine for a bacterial disease of tilapia, Francisella noatunensis subsp. orientalis (Fno), as a proof of concept to demonstrate the benefits of mucosal vaccination. The technology has the potential to be expanded to encompass other bacterial pathogens of fish in future polyvalent vaccines. Training and dissemination of the resulting technology to LMIC’s will be through a workshop in Vietnam.

Project outcomes

Although tilapia is a well-established cultured species globally, there are few effective commercial vaccines available or used in this species. Tilapia is one of the most important species farmed in developing countries and the majority of diseases in tilapia are bacterial, with treatment by antibiotics common. The benefits of application of vaccine to fish by immersion or oral routes are numerous; ease of application being the foremost especially in less developed countries where expensive vaccination machines are not feasible for farmers. Many fish farmers in LMIC countries would benefit from immersion and oral vaccines that can protect their stocks for the duration of production. Development and optimisation of mucosal vaccines is essential to provide protection of aquaculture species worldwide and contribute to reducing the use of antibiotics and thereby antibiotic resistance.

The current work was performed to optimise the use of mucosal vaccines for tilapia by adapting an existing bacterial vaccine against Francisella noatunensis subsp. orientalis (Fno) as a proof of concept. The vaccine has been shown to provide excellent protection by injection (RPS 82%) as part of a previous study. The current study aimed to optimise the formulation and dose of the Fno vaccine and mucosal adjuvants for oral and immersion delivery. A combination of vaccination routes and booster were tested to optimise vaccine efficacy: immersion/immersion and immersion/oral regimes and also by oral gavage. Uptake of vaccine in tissues and specific antibody responses in serum and mucus were measured.

For efficacy testing of the vaccine, duplicate groups of tilapia were vaccinated by different combinations of routes, for a total of 65 days with a booster at 15 days. Blood and mucus samples were taken for measurement of antibody responses. Efficacy of the vaccines was tested by immersion challenge with a virulent isolate of Fno at 65 days post-vaccination. Interestingly, the uptake study to optimise doses found specific antibody levels were significantly elevated in serum and mucus of fish given the adjuvanted vaccine by gavage. However, significant protection was not induced by any of the vaccine route combinations following challenge. The group vaccinated by immersion with an oral booster had the highest protection with a relative percentage survival of 28%.

Oral vaccination of fish has been problematic due to the need for production of large amounts of antigen, the need to protect the antigen from the harsh environment of the stomach and the lack of knowledge as to immune induction on the one hand and induction of tolerance on the other. The lack of efficacy of oral and immersion vaccines for fish is also attributed to the lack of mucosal adjuvants.

Adjuvants are essential components of the highly protective injectable vaccines available in aquaculture, for example in salmonid species. Therefore, the induction of high levels of specific antibodies against a bacterial pathogen in tilapia as demonstrated by the oral vaccine in conjunction with a novel oral adjuvant (by gavage) in this project is very promising. Further studies are needed to optimise delivery of the oral vaccine in a manner feasible to use on farms.

Professor Calman MacLennan

MRC Senior Clinical Fellow, Jenner Investigator and Group Leader
Jenner Institute, University of Oxford (UK)

Collaborators:
Professor Sanjay Ram, University of Massachusetts Medical School (USA)

Dr Paula Freixeiro, Jenner Institute, University of Oxford (UK)

Dr Christine Rollier, Oxford Vaccine Group, University of Oxford (UK)

Dr Robert W. Kaminski, Walter Reed Army Institute of Research (WRAIR) (USA)

Dr Sinead Delany-Moretlwe, University of the Witwatersrand (South Africa)

Summary

Gonorrhoea, a sexual transmitted infection, is a global problem disproportionately affecting women and infants in LMICs. Complications include pelvic inflammatory disease, ectopic pregnancy, infertility and infant blindness. The problem is exacerbated by increasing resistance to antibiotics which threatens to make gonorrhoea untreatable. There is no licensed gonococcal vaccine. However, a retrospective study of the MenZB meningococcal outer membrane vesicle (OMV) vaccine in New Zealand estimated 31% effectiveness against gonorrhoea. Gonococcus is closely related to meningococcus. We hypothesise that OMV produced from gonococcus instead of meningococcus will better protect against gonorrhoea than MenZB. We have genetically modified a circulating gonococcal strain to produce a gonococcal OMV-based candidate vaccine. This can induce an immune response in mice. We need to understand whether this or a similar candidate OMV vaccine can confer protection.

To test our hypothesis, we will evaluate gonococcal OMVs in the mouse gonorrhoea model. To maximise our chance of success, we will engineer a meningococcal and second gonococcal strain to produce two further OMV vaccine candidates replicating our vaccine design. All three OMV vaccines will be characterised and tested in the mouse gonorrhoea model compared with Bexsero, the commercial four-component meningococcal vaccine which contains MenZB OMVs. If one of our OMV candidate vaccines accelerates clearance of gonococcal infection in mice, this will support advancing the vaccine into clinical development and testing in humans. Finally, we will explore the immunological mechanisms behind the action of the OMV candidates, to help identify correlates of protection that will be valuable for clinical development.

Project outcomes

Background: Neisseria gonorrhoeae (gonococcus) causes 87 million cases of gonorrhea annually with women in low- and middle-income countries disproportionately affected. Rapid emergence of multi-drug resistant gonococcus threatens to make these infections untreatable. The need for a gonococcal vaccine is pressing, but none is available. A retrospective study in New Zealand with Neisseria meningitidis (meningococcus) group B vaccine MeNZB found 31% protection against gonorrhea. MeNZB consists of detergent-extracted outer membrane vesicles (dOMV) and is a components of GSK’s Bexsero (4CMenB) meningococcal group B vaccine.

Aim/Methods: We hypothesised that a gonococcal OMV-based vaccine will have greater efficacy against gonorrhea than a meningococcal OMV-based vaccine. We developed native OMV (NOMV) candidate gonococcal vaccines from recent Chilean gonococcal strain GC_0817560 and laboratory gonococcal strain FA1090. lpxL1 and rmp genes were deleted to reduce reactogenicity, minimize production of potentially unprotective antibodies and increase NOMV yield. NOMV were harvested from bacterial cultures by filtration and ultracentrifugation, characterised for physical properties and formulated with aluminum hydroxide to give candidates dmGC_0817560 NOMV and dmFA1090 NOMV. Immunogenicity and ability to accelerate clearance of FA1090 gonococcal infection compared with Bexsero following parental administration was assessed in the vaginal colonization model in estradiol-treated BALB/c mice.

Results: Deletion of lpxL1 from GC_0817560 and FA1090 resulted in a pentacylated form of lipid A that induced a marked reduction in IL-6 release from human PBMCs, while deletion of rmp further reduced IL-6 release and resulted in increased NOMV yield. dmGC_0817560 NOMV and dmFA1090 NOMV induced gonococcal specific serum and vaginal mucosal IgG and IgA antibodies and gonococcal-specific Th1/Th17 CD4+ T-cell responses. Gonococcal NOMV accelerated clearance of FA1090 from estradiol-treated BALB/c mice significantly faster than Bexsero (P<0.0001). There was no significant difference in clearance of FA1090 by dmGC_0817560 NOMV and dmFA1090 NOMV.

Conclusion: We have demonstrated that candidate gonococcal OMV-based vaccines can clear both homologous and heterologous gonococcal infection in the mouse vaginal gonorrhea model more quickly than meningococcal-vesicle-containing vaccine Bexsero. dmGC_0817560 NOMV represents a promising candidate for further development as a vaccine against gonorrhea.

Dr Sudaxshina Murdan

Associate Professor
School of Pharmacy University College London (UK)

Collaborators:
Dr Fatme Mawas, National Institute for Biological Standards and Control, MHRA (UK)

Dr Seanette Wilson, The Biovac Institute (Biovac) (South Africa)

Summary

The aim of this project is to investigate whether administering a vaccine under the tongue (i.e. sublingually) is more effective than injecting the vaccine, with the goal of preventing infections such as those caused by group A and group B streptococci bacteria. Infections caused by these bacteria result in significant illness and mortality burden, especially in low and middle income countries, and there are no vaccines against these streptococci. A new type of vaccine against group B streptococcus is currently being developed by the industrial partner, and this vaccine will be used to test the aim.

The sublingual route has been selected for its advantages over the injection. Injected vaccines do not always elicit immune responses at the body’s surfaces where group A and group B streptococci enter, infect or are transmitted to others, such as the nose, mouth, intestine, lungs and vagina. In contrast, when vaccines are administered sublingually, immune responses are generated at these sites and in the blood. Immunity at all these places (elicited by sublingual vaccine administration) is therefore more likely to prevent infection by group A and group B streptococci. In addition, the sublingual route avoids the needle and associated problems. In this project, we will administer the vaccine sublingually to experimental animals. Control animals will receive the vaccine by injection. Immune responses in the blood, mouth, nose, intestine and vagina will be measured. The results will establish the potential superiority of the sublingual route for administration of the type of vaccine used.

Project outcomes

Group B Streptococcus (GBS) is a bacterium that is commonly present in adults, in the gut and vagina, and usually does not cause any harm. Occasionally, GBS is transmitted from the mother to the baby during birth, causing meningitis, septicaemia and pneumonia in the first week of life.

Despite the strategies currently in place to prevent GBS infection in newborns i.e. antibiotics given to the mother, on average in the UK, 2 babies a day develop a GBS infection, and as a result, one baby dies every week, while another baby survives with long-term disability in the UK. This shows the urgent need for additional strategies, such as vaccinating pregnant women (as vaccinating newborns is not feasible). However, there are no commercially-available vaccines yet.

We have investigated the possibility of giving pregnant women a vaccine under the tongue i.e. sublingually, so that there would be immunity in the vagina, which would in turn prevent transmission of GBS bacteria from the mother to the baby during vaginal birth. The sublingual route was chosen as it has been shown to generate immunity in the vagina for other vaccines and it is pain-free, practical, cheap and acceptable to patients. It is also needle-free, thus it does not require injection by trained professionals and eliminates needle-related problems, such as disease transmission from accidental needle-stick injuries or from reuse of contaminated needles.

Our experiments in the laboratory have shown that giving a GBS vaccine sublingually in the mouse (an animal model) did indeed generate immunity in the vagina. In addition, immunity was also generated in the mouth, in the gut and in the blood. Statistically, the sublingual route was more effective than the injection route at generating immunity in the vagina, mouth and gut. This shows that in order to prevent transmission of the GBS from the mother to the baby during vaginal birth, and afterwards once the baby is born, giving a vaccine sublingually should be the preferred option compared to the injection. In addition, the sublingual route was statistically as effective as the injection route at generating immunity in the blood. This means that the sublingual route can enable immunity generated by the mother during pregnancy to pass to the foetus via the placenta, which would also protect the newborn against developing a GBS infection.

Subsequent experiments with sublingual vaccination showed that it was possible to reduce the dose of the vaccine five-fold without affecting the immunity in the vagina, mouth, gut and blood. This would significantly reduce the cost of the vaccine. Other experiments have shown that it is also possible to reduce or replace a toxin-based adjuvant (vaccine helper) with a safer alternative without affecting the immunity greatly.

Dr Andrew Preston

Reader in Microbial Pathogenesis
University of Bath (UK)

Collaborator:
Antonio Sanchez, Laboratory of Biologicals and Reagents of Mexico, S.A. of C.V. (Birmex), National Institutes of Health (Mexico)

Summary

Bordetella pertussis, causes whooping cough, or pertussis, a serious disease of infants. Infants are vaccinated against pertussis worldwide. Whole cell pertussis vaccines are used in most of the developing world. They give good protection against disease but cause adverse reactions in many infants, attributed to the endotoxin activity of the lipid A region of B. pertussis LPS. This led to the development of acellular pertussis vaccines that protect infants from serious disease but induce a sub-optimal immunity. This is associated with a resurgence of pertussis in a number of the developed world countries using these vaccines. Thus, there is a need to develop improved pertussis vaccines that can be used worldwide.

In this project we will demonstrate the approach of genetically modifying B. pertussis lipid A to not only reduce its toxicity, but to engineer novel, beneficial immunogenicity (adjuvant activity). This will produce a novel pertussis WCV that is safer, and that induces superior immunity, to current ones.

This project addresses an unmet need to develop novel pertussis vaccines to combat pertussis resurgence and that are affordable worldwide. It will demonstrate proof-of-principle for the approach of engineering whole cell vaccines for specified immune responses that will be widely applicable to a wide range of bacteria. This includes some for which whole cell vaccines are already in use, others for which vaccines are being sought and in the future, novel pathogens for which vaccines might be needed.

Project outcomes

Combinatorial genetic engineering of the lipid A of Bordetella pertussis was performed, resulting in a panel of 50 B. pertussis lipid A variant strains. The immunogenicity of these strains was measured using in vitro assays and those strains inducing responses different from those to WT were identified. Interestingly, strains with both increased and decreased responses were generated by this approach.

Four strains with specific immunogenicity profiles are being tested for toxicity using assays validated for toxicity testing of pertussis vaccines. This project has identified strains that are candidates for further development for novel whole cell pertussis vaccines that have improved safety and efficacy profiles compared to current pertussis vaccines.

Dr Nadja Alexandra Vielot

Postdoctoral Research Associate
Family Medicine, University of North Carolina at Chapel Hill (USA)

Collaborators:
Professor Samuel Vilchez, National University of Nicaragua, León (Nicaragua)

Professor Neil French, University of Liverpool (UK)

Summary

While under-five mortality has steadily declined since 1990, declines in neonatal mortality are less pronounced. Group B Streptococcus (GBS) disease is the most common cause of infant sepsis and meningitis, causing approximately 90,000 deaths and 56,000 stillbirths globally in 2015. Mothers with rectovaginal GBS colonization can vertically transmit GBS to infants during labour, causing early-onset GBS disease (EOD). To prevent EOD, 60 countries have instituted national policies to provide intrapartum antibiotic prophylaxis (IAP) to women with GBS colonization or who meet certain GBS risk criteria. However, lack of universal GBS screening, particularly in low- and middle-income countries (LMIC) complicates EOD prevention. Further, late-onset GBS disease (LOD) can occur with horizontal mother-infant GBS transmission after the first week of life, and cannot be prevented with IAP. A prophylactic GBS vaccine administered late in pregnancy could prevent infant GBS infection.

Investigational GBS vaccines have shown safety and immunogenicity in Phase 2 trials. However, GBS serotype distribution in LMIC are largely unknown. We propose a study in León, Nicaragua, to guide serotype-specific GBS prevention strategies. We will first collect rectovaginal samples from pregnant women to characterize GBS serotype distribution and serotype coverage of candidate pentavalent and hexavalent GBS vaccines. Next, we will describe the frequency and patterns of co-colonization with multiple GBS serotypes in colonized women. This data will improve estimates of serotype-specific GBS vaccine effectiveness, providing evidence-based guidance for GBS vaccine development and policy-making.

Project outcomes

Rectovaginal colonization with group B Streptococcus (GBS) is the primary cause of neonatal sepsis globally. To inform maternal GBS vaccine development, we present preliminary results from an ongoing study of GBS colonization in pregnant women in León, Nicaragua.

We recruited pregnant women at public health clinics in León between 35-37 weeks gestation. We collected one vaginal and one rectal sample from each woman, and transported them to the study lab in modified Stuart’s transport medium. Samples were processed and cultured within 24 hours of collection using three methods: direct plating onto chromogenic agar for presumptive identification of GBS (CHROM); direct plating onto Columbia nalidixic acid (CNA) agar; and incubation in Todd Hewitt w/CAN (LIM) broth followed by plating onto CNA. Suspected GBS colonies underwent Gram stain, catalase test, CAMP test, and latex agglutination serology to confirm GBS. Positive serology was considered definitive for GBS colonization regardless of the culture method, and women with positive serology from either anatomical site were considered colonized with GBS.

We observed moderate agreement between culture methods: LIM versus CNA, k=0.47; LIM versus CHROM, k=0.44. Compared to serology as the gold standard, CNA culture was 30% sensitive for GBS detection; LIM was 56% sensitive; and CHROM was 76% sensitive. Based on serology, 62 women (20%) were colonized with GBS in the vagina, rectum, or both, based on bacterial culture. Thirty-six women were colonized at a single anatomical site, whereas 26 women were colonized at both sites. In two-thirds of women who were colonized with GBS, isolates were resistant to penicillin, the first-line drug for intrapartum antibiotic prophylaxis to prevent infant GBS infection.

Three colonies from each sample were randomly selected to undergo typing for any of the 10 known GBS serotypes. We identified a preponderance of types Ia (30%), II (29%), and III (19%), as well as 3 instances of co-colonization with multiple serotypes: Ib + III (n=2) and Ib + V (n=1). The distribution of GBS serotypes is consistent with regional and global estimates suggesting that types I-V account for the majority of rectovaginal colonization among pregnant women. Furthermore, all of the types detected in our study are included in candidate pentavalent and hexavalent GBS vaccines. If these vaccines are proven safe and efficacious, they could serve as a preferred alternative to penicillin-based GBS prevention, and could greatly reduce the burden of GBS colonization and subsequent infant GBS disease in Nicaragua.

Professor Brendan Wren

Professor of Microbial Pathogenesis
London School of Hygiene and Tropical Medicine (UK)

Collaborators:
Professor Stephen Baker, The University of Oxford (OUCRU) (Vietnam)

Dr Jennifer Dow, London School of Hygiene and Tropical Medicine (UK)

Summary

For the past 18 years the Wren group and others have pioneered Protein Glycan Coupling Technology (PGCT) for the production of low-cost recombinant glycoconjugate vaccines in host cells such as E. coli. The technology involves coupling a protein carrier to a glycan of vaccine potential (e.g. O-antigen or capsules) using a bacterial oligosaccharyltransferase in E. coli cells. This allows the production of an inexhaustible and renewal supply of pure cloned bioconjugate vaccine in a single step process. Low cost vaccines produced by the Wren group using PGCT include those to protect against pneumonia, tularemia and melioidosis. In addition, GSK/GlycoVaxyn have shown that PGCT can be used for the production of Shigella dysenteriae type 1 O-antigen coupled to the Pseudomonas carrier protein ExoA, this is currently in human vaccine trials. We will improve on this vaccine by 1) coupling Shigella carrier proteins, that the Baker group have shown in Vietnam to have vaccine potential in their own right, to the Shigella dysenteriae O-antigen and 2) couple the best Shigella protein candidates to additional Shigella O-antigens including Shigella sonnei. The double-hit approach of coupling candidate protein and glycan immunogens should allow for the production of broad-coverage effective Shigella vaccines. This pump priming grant will enable significant steps to be made towards producing a new generation of recombinant “Shigella plus” vaccines. The subsequent testing of these candidates will facilitate significant funds towards a human trialled vaccine and the overall aim to produce an effective low-cost broad-coverage Shigella vaccine – a current imperative in LMICs.

Project outcomes

Shigellosis remains a major cause of diarrheal disease in low income countries and causes substantial morbidity and mortality. A safe, effective Shigella vaccine that include coverage of Shigella sonnei is a current global imperative. In previous research the Baker lab identified 12 proteins by protein microarray analyses to be highly immunogenic in children infected with Shigella. Eight of these proteins were shown to raise antibody responses when injected into rabbits. Upon testing of the respective rabbit polyclonal sera for complement-mediated serum bactericidal activity (SBA) against Shigella, 6 of the 8 proteins had raised antibody responses with strong SBA activity.

In this study we cloned these six proteins (with glycotags) in an appropriate E. coli strain and demonstrated expression of these proteins. In parallel, we were also able to express the O-antigens from S. dysenteriae and S. sonnei appropriate E. coli strains. We were able to couple three of the six proteins (all from S. sonnei) to the S. dysenteriae O-antigen using our protein glycan coupling technology. The three new “Shigella plus” vaccine candidates are available for testing and evaluation.

Dr Qibo Zhang

Senior Lecturer in Immunology
Institute of Infection and Global Health
University of Liverpool (UK)

Collaborators:
Prof Tim Mitchell, University of Birmingham (UK)

Dr. Anna-Karin Maltais, Eurocine Vaccines AB (Sweden)

Summary

Streptococcus pneumoniae (pneumococcus) is a leading cause of bacterial pneumonia and sepsis in children particularly in LMIC countries. The most cost-effective public health intervention to reduce pneumococcal diseases is vaccination. However, despite the effectiveness of current polysaccharide-based vaccines, invasive pneumococcal disease  still affects significant numbers of people worldwide, due to the increase in cases caused by non-vaccine serotypes. Recent efforts focus on development of vaccines based on protein antigens, as they are likely to induce protection against most serotypes and cheaper to produce. As pneumococcus normally colonizes the nasopharynx, local immunisation via nasal spray potentially provides an alternative effective vaccination strategy which may not only be effective against invasive disease but also against local nasal carriage. Recent studies showed that immune T cell type (Th17) responses are critical in clearing pneumococcus from the nose and we demonstrated that a protein fragment from pneumococcus  strongly activate this Th17 cell. In this project, we aim to develop a novel vaccine based on this protein to be used as an intranasal spray vaccine against pneumococcal infection.  Vaccines as tools to reduce AMR has been well established including the use of pneumococcal conjugate vaccines. New vaccines against multiple serotypes of pneumococcus will likely make an even more significant impact to reduce antibiotic use and AMR. 

Project outcomes

Pneumococcus is a leading cause of bacterial pneumonia and sepsis in humans particularly in LMIC countries. The most cost-effective public health intervention to reduce pneumococcal diseases is vaccination. However, despite the effectiveness of current polysaccharide-based vaccines, invasive pneumococcal disease still affects significant numbers of people worldwide, due to the increase in cases caused by non-vaccine serotypes. Recent efforts focus on development of vaccines based on protein antigens, as they are likely to induce protection against most serotypes and cheaper to produce. Vaccines as tools to reduce antimicrobial resistance (AMR) has been well established including the use of pneumococcal conjugate vaccines. New vaccines against multiple serotypes of pneumococcus will likely make an even more significant impact to reduce antibiotic use and AMR.

We have identified a small pneumococcal protein molecule which activates significant T cell responses that correlate with protection against pneumococcal infection. Together with a vaccine adjuvant, it may become an effective intranasal spray vaccine preventing multiple serotypes of pneumococcal infection in humans.