Meningococcal serogroups A, C, W-135, and Y tetanus toxoid conjugate vaccine: a new conjugate vaccine against invasive meningococcal disease

Invasive meningococcal disease in older adults in North America and Europe: is this the time for action? A review of the literature

BACKGROUND

Neisseria meningitidis is an encapsulated Gram-negative diplococcus that asymptomatically colonises the upper respiratory tract in up to 25% of the population (mainly adolescents and young adults). Invasive meningococcal disease (IMD) caused by Neisseria meningitidis imposes a substantial public health burden,. The case fatality rate (CFR) of IMD remains high. IMD epidemiology varies markedly by region and over time, and there appears to be a shift in the epidemiology towards older adults. The objective of our review was to assess the published data on the epidemiology of IMD in older adults (those aged ≥ 55 years)in North America and Europe. Such information would assist decision-makers at national and international levels in developing future public health programmes for managing IMD.

METHODS

A comprehensive literature review was undertaken on 11 August 2020 across three databases: EMBASE, Medline and BIOSIS. Papers were included if they met the following criteria: full paper written in the English language; included patients aged ≥ 56 years; were published between 1/1/2009 11/9/2020 and included patients with either suspected or confirmed IMD or infection with N. meningitidis in North America or Europe. Case studies/reports/series were eligible for inclusion if they included persons in the age range of interest. Animal studies and letters to editors were excluded. In addition, the websites of international and national organisations and societies were also checked for relevant information.

RESULTS

There were 5,364 citations identified in total, of which 76 publications were included in this review. We identified that older adults with IMD were mainly affected by serogroups W and Y, which are generally not the predominant strains in circulation in most countries. Older adults had the highest CFRs, probably linked to underlying comorbidities and more atypical presentations hindering appropriate timely management. In addition, there was some evidence of a shift in the incidence of IMD from younger to older adults.

CONCLUSIONS

The use of meningococcal vaccines that include coverage against serogroups W and Y in immunization programs for older adults needs to be evaluated to inform health authorities' decisions of the relative benefits of vaccination and the utility of expanding national immunization programmes to this age group.

Reciprocal Packaging of the Main Structural Proteins of Type 1 Fimbriae and Flagella in the Outer Membrane Vesicles of "Wild Type" Escherichia coli Strains

Fundamental aspects of outer membrane vesicle (OMV) biogenesis and the engineering of producer strains have been major research foci for many in recent years. The focus of this study was OMV production in a variety of Escherichia coli strains including wild type (WT) (K12 and BW25113), mutants (from the Keio collection) and proprietary [BL21 and BL21 (DE3)] strains. The present study investigated the proteome and prospective mechanism that underpinned the key finding that the dominant protein present in E. coli K-12 WT OMVs was fimbrial protein monomer (FimA) (a polymerizable protein which is the key structural monomer from which Type 1 fimbriae are made). However, mutations in genes involved in fimbriae biosynthesis (ΔfimA, B, C, and F) resulted in the packaging of flagella protein monomer (FliC) (the major structural protein of flagella) into OMVs instead of FimA. Other mutations (ΔfimE, G, H, I, and ΔlrhA-a transcriptional regulator of fimbriation and flagella biosynthesis) lead to the packaging of both FimA and Flagellin into the OMVs. In the majority of instances shown within this research, the production of OMVs is considered in K-12 WT strains where structural appendages including fimbriae or flagella are temporally co-expressed throughout the growth curve as shown previously in the literature. The hypothesis, proposed and supported within the present paper, is that the vesicular packaging of the major FimA is reciprocally regulated with the major FliC in E. coli K-12 OMVs but this is abrogated in a range of mutated, non-WT E. coli strains. We also demonstrate, that a protein of interest (GFP) can be targeted to OMVs in an E. coli K-12 strain by protein fusion with FimA and that this causes normal packaging to be disrupted. The findings and underlying implications for host interactions and use in biotechnology are discussed.

Immunogenicity of trimeric autotransporter adhesins and their potential as vaccine targets

The current problem of increasing antibiotic resistance and the resurgence of numerous infections indicate the need for novel vaccination strategies more than ever. In vaccine development, the search for and the selection of adequate vaccine antigens is the first important step. In recent years, bacterial outer membrane proteins have become of major interest, as they are the main proteins interacting with the extracellular environment. Trimeric autotransporter adhesins (TAAs) are important virulence factors in many Gram-negative bacteria, are localised on the bacterial surface, and mediate the first adherence to host cells in the course of infection. One example is the Neisseria adhesin A (NadA), which is currently used as a subunit in a licensed vaccine against Neisseria meningitidis. Other TAAs that seem promising vaccine candidates are the Acinetobacter trimeric autotransporter (Ata), the Haemophilus influenzae adhesin (Hia), and TAAs of the genus Bartonella. Here, we review the suitability of various TAAs as vaccine candidates.

Incidence and Prevention of Invasive Meningococcal Disease in Global Mass Gathering Events

INTRODUCTION

Mass gathering events involve close contact among large numbers of people in a specific location at the same time, an environment conducive to transmission of respiratory tract illnesses including invasive meningococcal disease (IMD). This report describes IMD incidence at mass gatherings over the past 10 years and discusses strategies to prevent IMD at such events.

METHODS

A PubMed search was conducted in December 2018 using a search string intended to identify articles describing IMD at mass gatherings, including religious pilgrimages, sports events, jamborees, and refugee camps. The search was limited to articles in English published from 2008 to 2018. Articles were included if they described IMD incidence at a mass gathering event.

RESULTS

A total of 127 articles were retrieved, of which 7 reported on IMD incidence at mass gatherings in the past 10 years. Specifically, in Saudi Arabia between 2002 and 2011, IMD occurred in 16 Hajj pilgrims and 1 Umrah pilgrim; serotypes involved were not reported. At a youth sports festival in Spain in 2008, 1 case of serogroup B IMD was reported among 1500 attendees. At the 2015 World Scout Jamboree in Japan, an outbreak of serogroup W IMD was identified in five scouts and one parent. At a refugee camp in Turkey, one case of serogroup B IMD was reported in a Syrian girl; four cases of serogroup X IMD occurred in an Italian refugee camp among refugees from Africa and Bangladesh. In 2017, a funeral in Liberia resulted in 13 identified cases of serogroup C IMD. Requiring meningococcal vaccination for mass gathering attendees and vaccinating refugees might have prevented these IMD cases.

CONCLUSIONS

Mass gathering events increase IMD risk among attendees and their close contacts. Vaccines preventing IMD caused by serogroups ACWY and B are available and should be recommended for mass gathering attendees.

FUNDING

Pfizer.

Chimeric hepatitis B virus core particles displaying Neisserial surface protein A confer protection against virulent Neisseria meningitidis serogroup B in BALB/c mice

Purpose

The primary goal of the present study was to explore and evaluate the highly conserved Neisserial surface protein A (NspA) molecule, fused with truncated HBV virus-like particles (VLPs), as a candidate vaccine against the virulent Neisseria meningitidis serogroup B (NMB).

Methods

NspA was inserted into the major immunodominant region of the truncated hepatitis B virus core protein (HBc; amino acids 1–144). The chimeric protein, HBc-N144-NspA, was expressed from a prokaryotic vector and generated HBc-like particles, as determined by transmission electron microscopy. Further, the chimeric protein and control proteins were used to immunize mice and the resulting immune responses evaluated by flow cytometry, enzyme-linked immunosorbent assay, and analysis of serum bactericidal activity (SBA) titer.

Results

Evaluation of the immunogenicity of the recombinant HBc-N144-NspA protein showed that it elicited the production of high levels of NspA-specific total IgG. The SBA titer of HBc-N144-NspA/F reached 1:16 2 weeks after the last immunization in BALB/c mice, when human serum complement was included in the vaccine. Immunization of HBc-N144-NspA, even without adjuvant, induced high levels of IL-4 and a high IgG1 to IgG2a ratio, confirming induction of an intense Th2 immune response. Levels of IL-17A increased rapidly in mice after the first immunization with HBc-N144-NspA, indicating the potential for this vaccine to induce a mucosal immune response. Meanwhile, the immunization of HBc-N144-NspA without adjuvant induced only mild inflammatory infiltration into the mouse muscle tissue.

Conclusion

This study demonstrates that modification using HBc renders NspA a candidate vaccine, which can trigger protective immunity against NMB.

[Genotypes of Neisseria meningitidis isolates in patients with meningococcal meningitis in Paraguay, 1996-2015Genótipos de Neisseria meningitidis isolados de pacientes com doença meningocócica no Paraguai, 1996-2015]

Objetivo

Describir las características fenotípicas y genotípicas de cepas de Neisseria meningitidis aisladas de enfermedad meningocócica en Paraguay entre 1996 y 2015.

Métodos

Se estudiaron por métodos microbiológicos convencionales y técnicas moleculares 114 aislamientos de N. meningitidis y 12 muestras clínicas sin aislamiento confirmadas por reacción en cadena de la polimerasa (PCR) que fueron remitidas por los diferentes centros centinelas y centros colaboradores de Paraguay.

Resultados

El grupo de edad más afectado fue el de menores de 1 año (19,0%), seguido por el de 1 a 5 años (17,5%). Un mayor porcentaje de las cepas se aisló de casos de meningitis (81,7%) y el serogrupo B se encontró en 60,3% de los casos. Los fenotipos más frecuentes fueron B:4:P1.14 (16,0%), B:15:P1.5, C:NT:NST y W:NT:P1.2 (10,5%), respectivamente. Los complejos clonales prevalentes fueron ST-11/ET37 complex 29,6% (8/27) con predominio del serogrupo W (6/8), ST-35 complex 18,5% (5/27) en el serogrupo B (4/4), y ST-32/ET5 complex 14,8% (4/16) en el serogrupo B (5/5).

Conclusiones

En Paraguay la enfermedad meningocócica es relativamente infrecuente. Los análisis de distribución de serogrupo muestran que el más frecuente es el B y en los últimos dos años aumentaron los casos de enfermedad meningocócica por C y W. Los complejos clonales encontrados se correlacionan con los hallados en la región del Cono Sur. Debido al alto nivel de virulencia de N. meningitidis, su vigilancia debe constituir una prioridad estratégica de los sistemas de salud pública nacionales y regionales para prevenir brotes epidémicos y apoyar la toma de decisiones en salud pública.

Bioinformatic analysis of meningococcal Msf and Opc to inform vaccine antigen design

Neisseria meningitidis is an antigenically and genetically variable Gram-negative bacterium and a causative agent of meningococcal meningitis and septicaemia. Meningococci encode many outer membrane proteins, including Opa, Opc, Msf, fHbp and NadA, identified as being involved in colonisation of the host and evasion of the immune response. Although vaccines are available for the prevention of some types of meningococcal disease, none currently offer universal protection. We have used sequences within the Neisseria PubMLST database to determine the variability of msf and opc in 6,500 isolates. In-silico analysis revealed that although opc is highly conserved, it is not present in all isolates, with most isolates in clonal complex ST-11 lacking a functional opc. In comparison, msf is found in all meningococcal isolates, and displays diversity in the N-terminal domain. We identified 20 distinct Msf sequence variants (Msf SV), associated with differences in number of residues within the putative Vn binding motifs. Moreover, we showed distinct correlations with certain Msf SVs and isolates associated with either hyperinvasive lineages or those clonal complexes associated with a carriage state. We have demonstrated differences in Vn binding between three Msf SVs and generated a cross reactive Msf polyclonal antibody. Our study has highlighted the importance of using large datasets to inform vaccine development and provide further information on the antigenic diversity exhibited by N. meningitidis.

Meningococcal Vaccines: Current Status and Emerging Strategies

Neisseria meningitidis causes most cases of bacterial meningitis. Meningococcal meningitis is a public health burden to both developed and developing countries throughout the world. There are a number of vaccines (polysaccharide-based, glycoconjugate, protein-based and combined conjugate vaccines) that are approved to target five of the six disease-causing serogroups of the pathogen. Immunization strategies have been effective at helping to decrease the global incidence of meningococcal meningitis. Researchers continue to enhance these efforts through discovery of new antigen targets that may lead to a broadly protective vaccine and development of new methods of homogenous vaccine production. This review describes current meningococcal vaccines and discusses some recent research discoveries that may transform vaccine development against N. meningitidis in the future.

Knowing the scope of meningococcal disease in Latin America

Opportunities for strengthening surveillance of meningococcal disease exist between and within countries in Latin America. In August of 2015, a workshop was convened in the city of São Paulo, Brazil, to address the following objectives: 1) to review meningococcal disease burden and vaccine use in Latin America; 2) to evaluate the effectiveness of current meningococcal surveillance practices in the region; 3) to identify challenges to meningococcal surveillance in the region; and 4) to outline steps for strengthening meningococcal surveillance and disease control in the region. Based on the workshop’s discussions, recommendations for strengthening surveillance and controlling meningococcal disease in Latin America focus on improving: a) laboratory capabilities for diagnostic testing; b) communication regarding epidemiologic- and laboratory-based analyses; c) communication during outbreaks; d) monitoring of long-term disease outcomes; e) knowledge of vaccines against serogroup B disease; and f) criteria for defining and controlling meningococcal outbreaks. Overall, improving surveillance will help guide strategies for meningococcal disease prevention and control in Latin America.

Immune response to vaccines is maintained in patients treated with dimethyl fumarate

Objectives:

To investigate the immune response to vaccinations in patients with relapsing forms of MS treated with delayed-release dimethyl fumarate (DMF) vs nonpegylated interferon (IFN).

Methods:

In this open-label, multicenter study, patients received 3 vaccinations: (1) tetanus-diphtheria toxoid (Td) to test T-cell–dependent recall response, (2) pneumococcal vaccine polyvalent to test T-cell–independent humoral response, and (3) meningococcal (groups A, C, W-135, and Y) oligosaccharide CRM₁₉₇ conjugate to test T-cell–dependent neoantigen response. Eligible patients were aged 18–55 years, diagnosed with relapsing-remitting MS (RRMS), and either treated for ≥6 months with an approved dose of DMF or for ≥3 months with an approved dose of nonpegylated IFN. Primary end point was the proportion of patients with ≥2-fold rise in antitetanus serum IgG levels from prevaccination to 4 weeks after vaccination.

Results:

Seventy-one patients (DMF treated, 38; IFN treated, 33) were enrolled. The mean age was 45.3 years (range 27–55); 86% were women. Responder rates (≥2-fold rise) to Td vaccination were comparable between DMF- and IFN-treated groups (68% vs 73%). Responder rates (≥2-fold rise) were also similar between DMF- and IFN-treated groups for diphtheria antitoxoid (58% vs 61%), pneumococcal serotype 3 (66% vs 79%), pneumococcal serotype 8 (95% vs 88%), and meningococcal serogroup C (53% vs 53%), all p > 0.05. In a post hoc analysis, no meaningful differences were observed between groups in the proportion of responders when stratified by age category or lymphocyte count.

Conclusions:

DMF-treated patients mount an immune response to recall, neoantigens, and T-cell–independent antigens, which was comparable with that of IFN-treated patients and provided adequate seroprotection.

ClinicalTrials.gov identifier:

NCT02097849.

Classification of evidence:

This study provides Class II evidence that patients with RRMS treated with DMF respond to vaccinations comparably with IFN-treated patients.

Trends in therapeutic drug conjugates for bacterial diseases: a patent review

INTRODUCTION

Drug conjugates are trend topics in Chemical Biology. These entities are an emerging class of highly potent biopharmaceutical drugs, best known in the field of oncology, that have been also designed as a targeted therapy/diagnosis for the treatment/prevention of several bacterial diseases. Antibiotic resistance is now a major threat to public health, and targeted strategies can reduce resistance. The following review aims at giving an overview of the patented therapeutic innovations covering these areas. Particular attention has been given to antibacterial drug conjugates in the last 30 years. Areas covered: The authors provide an overview of the scientific reports describing the research and development of new drug conjugates for bacterial diseases. The review emphasizes the rationale behind synthesis, biological activities and improvement of the new drug conjugates. New technologies applied for the research in this field have also been discussed. The article is based on the most relevant literature related to the development of new therapeutic solutions. The patents presented in this review have been collected from multiple electronic databases including SciFinder, Pubmed, Espacenet and Mendeley. Expert opinion: The new drug conjugates described in the current review proved to display improved delivery, efficacy, targeting abilities and fewer side effects. Versatile approaches were invented to achieve these goals.

Meningococcal quadrivalent tetanus toxoid conjugate vaccine (MenACWY-TT, Nimenrix™): A review of its immunogenicity, safety, co-administration, and antibody persistence

INTRODUCTION

Meningococcal disease is a major cause of morbidity and mortality worldwide with reported epidemics and outbreaks in different parts of the world. Despite the availability of antimicrobial therapy, challenges remain in early recognition and prevention of disease. Several vaccines have been developed to date aiming at preventing disease spread.

DISCUSSION

MenACWY-TT (Nimenrix™) has been extensively studied for use in different age groups. Phase II and III randomized trials have demonstrated its immunogenicity when administered in children aged 1 year and older, adolescents and adults. It has an acceptable safety profile with minor adverse events comparable to other vaccines. Follow up studies have shown persistence of protective antibodies up to three years. MenACWY-TT was safely and effectively co-administered with different recommended vaccines.

CONCLUSION

MenACWY-TT is a safe and immunogenic vaccine that can be used to protect against these four serogroups in individuals older than 1 year of age.

A Synthetic Disaccharide Analogue from Neisseria meningitidis A Capsular Polysaccharide Stimulates Immune Cell Responses and Induces Immunoglobulin G (IgG) Production in Mice When Protein-Conjugated

Some new phosphonoester-linked oligomers, stabilized analogues of the corresponding phosphate-bridged oligomers of Neisseria meningitidis A (MenA) capsular polysaccharide (CPS), were conjugated to human serum albumin (HSA), as a protein carrier model, and studied for immunological activities. We determined (i) in vitro, their biocompatibility (CAM test) and activity in inducing both T cell proliferation (CFSE method) and IL-2 release (ELISA), and (ii) in vivo, their ability to stimulate specific IgG antibody production (ELISA). All HSA-conjugated compounds induce T cell proliferation (40% of proliferation at 10(2) μM), whereas only the phosphonodisaccharide was effective (28% of proliferation at 10(2) μM) among the unconjugated forms. IL-2 release confirmed these results. In addition, the HSA-conjugated showed in vivo the capacity of eliciting the production of specific IgG antibodies. In conclusion, we obtained novel biocompatible, water-stable, and immunoactive MenA CPS analogues. A short disaccharide fragment showed the unusual behavior of triggering T cell proliferation in vitro.

Meningococcal disease in childhood: epidemiology, clinical features and prevention

Invasive meningococcal disease (IMD) represents a public health problem and a leading cause of morbidity and mortality worldwide. IMD can occur as an endemic disease with sporadic cases or epidemics with outbreaks. Neisseria meningitis strains are divided into 13 serogroups, but only five (A, B, C, W-135, and Y) are responsible for most IMD across the world. All age groups are at risk for IMD, but infants and adolescents are particularly vulnerable. The most common clinical manifestations of IMD are meningitis and septicemia, although in some cases both clinical pictures are present. The clinical pattern can differ according to age; in young children, the clinical manifestations may be more insidious and the diagnosis may be more difficult compared to older children or adolescents. Death occurs in 6-10% of cases and sequelae in 4.3-11.2% of cases. Early recognition of children with meningococcal infection is important in order to initiate systemic antibiotic therapy, although vaccination remains the best strategy to control meningococcal disease. Recently, different meningococcal vaccines have been introduced worldwide, resulting in a reduction in the overall burden of the disease. The goal of the next few years should be to increase vaccination coverage against meningococcal diseases, continue to monitor IMD and develop a unique vaccine able to cover all of the main meningococcal strains.

A fusion protein derived from Moraxella catarrhalis and Neisseria meningitidis aimed for immune modulation of human B cells

Moraxella IgD-binding protein (MID) is a well characterized trimeric autotransporter that specifically targets the IgD of B cells. We fused the membrane anchor of the meningococcal autotransporter NhhA with the IgD-binding region of MID (aa 962-1200) to create a chimeric protein designated as NID. The aim was to use this specific targeting to provide a better vaccine candidate against meningococci, in particular serogroup B by enhancing the immunogenicity of NhhA. NID was thereafter recombinantly expressed in E. coli. The NID-expressing E. coli bound to peripheral B lymphocytes that resulted in cellular activation. Furthermore, we also successfully expressed NID on outer membrane vesicles, nanoparticles that are commonly used in meningococcal vaccines. This study thus highlights the applicability of the menigococcal-Moraxella fusion protein NID to be used for specific targeting of vaccine components to the IgD B cell receptor.

Safety and immunogenicity of typhoid fever and yellow fever vaccines when administered concomitantly with quadrivalent meningococcal ACWY glycoconjugate vaccine in healthy adults

BACKGROUND

Compact and short pre-travel immunization schedules, which include several vaccinations in a single visit, are desirable for many travelers. However, concomitant vaccination could potentially compromise immunogenicity and/or safety of the individual vaccines and, therefore, possible vaccine interferences should be carefully assessed. This article discusses the immunogenicity and safety of travel vaccines for typhoid fever (TF) and yellow fever (YF), when administered with or without a quadrivalent meningococcal glycoconjugate ACWY-CRM vaccine (MenACWY-CRM).

METHODS

Healthy adults (18-≤60 years) were randomized to one of three vaccine regimens: TF + YF + MenACWY-CRM (group I; n = 100), TF + YF (group II; n = 101), or MenACWY-CRM (group III; n = 100). Immunogenicity at baseline and 4 weeks post-vaccination (day 29) was assessed by serum bactericidal assay using human complement (hSBA), enzyme-linked immunosorbent assay (ELISA), or a neutralization test. Adverse events (AEs) and serious adverse events (SAEs) were collected throughout the study period.

RESULTS

Non-inferiority of post-vaccination geometric mean concentrations (GMCs) and geometric mean titers (GMTs) was established for TF and YF vaccines, respectively, when given concomitantly with MenACWY-CRM vaccine versus when given alone. The percentages of subjects with seroprotective neutralizing titers against YF on day 29 were similar in groups I and II. The antibody responses to meningococcal serogroups A, C, W-135, and Y were within the same range when MenACWY-CRM was given separately or together with TF and YF vaccines. The percentage of subjects reporting AEs was the same for TF and YF vaccines with or without MenACWY-CRM vaccine. There were no reports of SAEs or AEs leading to study withdrawals.

CONCLUSIONS

These data provide evidence that MenACWY-CRM can be administered with typhoid Vi polysaccharide vaccine and live attenuated YF vaccine without compromising antibody responses stimulated by the individual vaccines. MenACWY-CRM can, therefore, be incorporated into travelers' vaccination programs without necessitating an additional clinic visit (NCT01466387).

Vaccination against infectious diseases: what is promising?

Vaccination has proven to be one of the best weapons protecting the mankind against infectious diseases. Along with the huge progress in microbiology, numerous highly efficacious and safe vaccines have been produced by conventional technology (cultivation), by the use of molecular biology (genetic modification), or by synthetic chemistry. Sterilising prevention is achieved by the stimulation of antibody production, while the stimulation of cell-mediated immune responses may prevent the outbreak of disease in consequence of an acute or reactivated infection. From several examples, two rules are deduced to evaluate the perspectives of future vaccine developments: They are promising, if (1) the natural infectious disease induces immunity or (2) passive immunisation (transfer of antibodies, adoptive transfer of lymphocytes) is successful in preventing infection.

[Meningococcus B: control of two outbreaks by vaccination]

The issue of an effective vaccine against Meningococcus B (MenB) has been overcome by identifying, with the "reverse vaccinology" methodology, some antigens able of inducing a response to the majority of MenB strains circulating in the world. The new 4-components MenB vaccine (4CMenB) has been approved in Europe, Australia and Canada, and included in international pediatric immunization schedules: Australia, Canada, UK. In Italy, the first regions that have recommended vaccination against MenB were Basilicata and Puglia. The management of epidemics/outbreaks requires the implementation of a rapid response by health authorities in respect of a medical emergency with a high impact, even emotional, on the population, as recently demonstrated in two American universities. The declaration of outbreak in place has been followed in both contexts by the adoption of a procedure for the use of the 4CMenB vaccine not yet licensed in the USA. It was thus possible to organize interventions of active prophylaxis in the two campuses, establishing the first large-scale use of the new 4CMenB vaccine and achieving, in a relatively short time, high rates of vaccination coverage. With around 14,000 students immunized with at least one dose, no safety issues have been reported following immunization. Besides, to date there have been no cases in subjects who have received the vaccine. As a result of the two outbreaks described, FDA is now evaluating for the extension of the use of the 4CMenB vaccine in adolescents and young adults in USA.