Antibodies from Sierra Leonean and Nigerian Lassa fever survivors cross-react with recombinant proteins representing Lassa viruses of divergent lineages.

Lassa virus (LASV) is the causative agent of Lassa fever, an often-fatal hemorrhagic disease that is endemic in West Africa. Seven genetically distinct LASV lineages have been identified. As part of CEPI's (Coalition for Epidemic Preparedness Innovations) Lassa vaccine development program, we assessed the potential of the human immune system to mount cross-reactive and cross-protective humoral immune responses to antigens from the most prevalent LASV lineages, which are lineages II and III in Nigeria and lineage IV in Sierra Leone. IgG and IgM present in the blood of Lassa fever survivors from Nigeria or Sierra Leone exhibited substantial cross-reactivity for binding to LASV nucleoprotein and two engineered (linked and prefusion) versions of the glycoproteins (GP) of lineages II-IV. There was less cross-reactivity for the Zinc protein. Serum or plasma from Nigerian Lassa fever survivors neutralized LASV pseudoviruses expressing lineage II GP better than they neutralized lineage III or IV GP expressing pseudoviruses. Sierra Leonean survivors did not exhibit a lineage bias. Neutralization titres determined using LASV pseudovirus assays showed significant correlation with titres determined by plaque reduction with infectious LASV. These studies provide guidance for comparison of humoral immunity to LASV of distinct lineages following natural infection or immunization.

Correction to: Developing vaccines against epidemic-prone emerging infectious diseases.

In the original publication of this article, the author name Richard Hatchett was incorrectly published.

Developing vaccines against epidemic-prone emerging infectious diseases.

Today's world is characterized by increasing population density, human mobility, urbanization, and climate and ecological change. This global dynamic has various effects, including the increased appearance of emerging infectious diseases (EIDs), which pose a growing threat to global health security.Outbreaks of EIDs, like the 2013-2016 Ebola outbreak in West Africa or the current Ebola outbreak in Democratic Republic of the Congo (DRC), have not only put populations in low- and middle-income countries (LMIC) at risk in terms of morbidity and mortality, but they also have had a significant impact on economic growth in affected regions and beyond.The Coalition for Epidemic Preparedness Innovation (CEPI) is an innovative global partnership between public, private, philanthropic, and civil society organizations that was launched as the result of a consensus that a coordinated, international, and intergovernmental plan was needed to develop and deploy new vaccines to prevent future epidemics.CEPI is focusing on supporting candidate vaccines against the World Health Organization (WHO) Blueprint priority pathogens MERS-CoV, Nipah virus, Lassa fever virus, and Rift Valley fever virus, as well as Chikungunya virus, which is on the WHO watch list. The current vaccine portfolio contains a wide variety of technologies, ranging across recombinant viral vectors, nucleic acids, and recombinant proteins. To support and accelerate vaccine development, CEPI will also support science projects related to the development of biological standards and assays, animal models, epidemiological studies, and diagnostics, as well as build capacities for future clinical trials in risk-prone contexts.

Exploring Vaccine Hesitancy Through an Artist-Scientist Collaboration : Visualizing Vaccine-Critical Parents' Health Beliefs.

This project explores vaccine hesitancy through an artist-scientist collaboration. It aims to create better understanding of vaccine hesitant parents' health beliefs and how these influence their vaccine-critical decisions. The project interviews vaccine-hesitant parents in the Netherlands and Finland and develops experimental visual-narrative means to analyse the interview data. Vaccine-hesitant parents' health beliefs are, in this study, expressed through stories, and they are paralleled with so-called illness narratives. The study explores the following four main health beliefs originating from the parents' interviews: (1) perceived benefits of illness, (2) belief in the body's intelligence and self-healing capacity, (3) beliefs about the "inside-outside" flow of substances in the body, and (4) view of death as a natural part of life. These beliefs are interpreted through arts-based diagrammatic representations. These diagrams, merging multiple aspects of the parents' narratives, are subsequently used in a collaborative meaning-making dialogue between the artist and the scientist. The resulting dialogue contrasts the health beliefs behind vaccine hesitancy with scientific knowledge, as well as the authors' personal, and differing, attitudes toward these.

Variability of genes encoding surface proteins used as vaccine antigens in meningococcal endemic and epidemic strain panels from Norway.

Surface-expressed protein antigens such as factor H-binding protein (fHbp), Neisserial adhesin A (NadA), Neisserial heparin-binding antigen (NHBA) and Porin protein A (PorA); all express sequence variability that can affect their function as protective immunogens when used in meningococcal serogroup B vaccines like the recently-approved 4CMenB (Bexsero(®)). We assessed the sequence variation of genes coding for these proteins and two additional proteins ("fusion partners" to fHbp and NHBA) in pathogenic isolates from a recent low incidence period (endemic situation; 2005-2006) in Norway. Findings among strains from this panel were contrasted to what was found among isolates from a historic outbreak (epidemic situation; 1985-1990). Multilocus sequence typing revealed 14 clonal complexes (cc) among the 66 endemic strains, while cc32 vastly predominated in the 38-strain epidemic panel. Serogroup B isolates accounted for 50/66 among endemic strains and 28/38 among epidemic strains. Potential strain-coverage ("sequence match") for the 4CMenB vaccine was identified among the majority (>70%) of the endemic serogroup B isolates and all of the epidemic serogroup B isolates evaluated. Further information about the degree of expression, surface availability and the true cross-reactivity for the vaccine antigens will be needed to fully characterize the clinical strain-coverage of 4CMenB in various geographic and epidemiological situations.

Vaccines against meningococcal serogroup B disease containing outer membrane vesicles (OMV): lessons from past programs and implications for the future.

The utility of wild-type outer membrane vesicle (wtOMV) vaccines against serogroup B (MenB) meningococcal disease has been explored since the 1970s. Public health interventions in Cuba, Norway and New Zealand have demonstrated that these protein-based vaccines can prevent MenB disease. Data from large clinical studies and retrospective statistical analyses in New Zealand give effectiveness estimates of at least 70%. A consistent pattern of moderately reactogenic and safe vaccines has been seen with the use of approximately 60 million doses of three different wtOMV vaccine formulations. The key limitation of conventional wtOMV vaccines is their lack of broad protective activity against the large diversity of MenB strains circulating globally. The public health intervention in New Zealand (between 2004-2008) when MeNZB was used to control a clonal MenB epidemic, provided a number of new insights regarding international and public-private collaboration, vaccine safety surveillance, vaccine effectiveness estimates and communication to the public. The experience with wtOMV vaccines also provide important information for the next generation of MenB vaccines designed to give more comprehensive protection against multiple strains.

Considerations for controlling invasive meningococcal disease in high income countries.

The development of conjugate vaccines has enabled the prevention and control of Neisseria meningitidis caused by serogroups A, C, W-135 and Y. Vaccines that provide protection against a broad number of serogroup B strains likely will be available soon to enable greater control of meningococcal disease in high income countries. We present an argument for adequate post-marketing surveillance to monitor epidemiological shifts and to provide a context for the safety and reactogenicity of serogroup B vaccines, including the newer recombinant vaccines. We also offer a series of recommendations to address possible concerns about vaccine safety.

The Global Meningococcal Initiative: recommendations for reducing the global burden of meningococcal disease.

The Global Meningococcal Initiative (GMI) is composed of an international group of scientists, clinicians and public health officials with expertise in meningococcal immunology, epidemiology and prevention. The primary goal of the GMI is the promotion of the global prevention of invasive meningococcal disease through education and research. The GMI members reviewed global meningococcal disease epidemiology, immunization strategies, and research needs. Over the past decade, substantial advances in meningococcal vaccine development have occurred and much has been learned about prevention from countries that have incorporated meningococcal vaccines into their immunization programs. The burden of meningococcal disease is unknown for many parts of the world because of inadequate surveillance, which severely hampers evidence-based immunization policy. As the field of meningococcal vaccine development advances, global surveillance for meningococcal disease needs to be strengthened in many regions of the world. For countries with meningococcal vaccination policies, research on vaccine effectiveness and impact, including indirect effects, is crucial for informing policy decisions. Each country needs to tailor meningococcal vaccination policy according to individual country needs and knowledge of disease burden. Innovative approaches are needed to introduce and sustain meningococcal vaccination programs in resource-poor settings with a high incidence of meningococcal disease.

2nd international workshop on Neisseria vaccines (Neisseria vaccines 2009).

A 5-day workshop on Neisseria vaccines was held in Varadero, Cuba, 17-22 May 2009, and hosted by the Latin American Association for Immunology and the Cuban Society for Immunology, which attracted more than 100 scientists from different parts of the world. The meeting summarizes current knowledge regarding Neisseria species vaccine development, including plain polysaccharide vaccines, conjugate polysaccharides and protein-based vaccines. Main discussion topics were the discovery of new potential antigens with protective capacity, current and new vaccines, pathogenesis and immune response, clinical trials and alternative correlates of protection and manufacture, control and regulation, gonococcus vaccines, and adjuvant as the main component of Neisseria vaccines. Seven keynote addresses, 32 oral presentations, 49 posters and an International Vaccine Course were presented. The meeting was concluded with a 'Hot Topics' session discussing future challenges. This article highlights the most important issues presented.

Properties and clinical performance of vaccines containing outer membrane vesicles from Neisseria meningitidis.

Meningococcal outer membrane proteins have been used for over 20 years in more than 80 million doses; either as carrier protein in a Haemophilus influenzae type b (Hib) polysaccharide conjugate vaccine or as vesicle vaccine formulations against meningococcal disease. Conventional wild-type outer membrane vesicle (wtOMV) vaccines are the only formulations that have shown efficacy against serogroup B meningococcal disease. This has been demonstrated in Cuba, Norway and New Zealand; where epidemics, dominated by one particular strain or clone, were causing high rates of disease and wtOMV vaccines have been used for epidemic control. The most significant limitation for widespread use of wtOMV is that the immune response is strain-specific in infants, mostly directed against the immuno-dominant porin protein, PorA. The natural orientation of surface-exposed membrane antigens and the preservation of good physico-chemical stability are key features of OMV vaccines. The efficacy, tolerability and safety of wtOMV vaccines have been well proven. The most recent experience from New Zealand demonstrated a vaccine effectiveness of 80% for children less than 5 years of age, over a period of 24 months. Such results are encouraging for the further use of "tailor-made" OMV vaccines for epidemic control. Moreover, it provides opportunities for development of OMV vaccines with various additional cross-protective potential. There is good reason to believe that in the coming few years the "OMV-concept" will be exploited further and that a number of cross-protective "universal" antigens will be included in vaccines against serogroup B meningococcal disease. The desire to have a global vaccine strategy that enables susceptible individuals to be protected against all the relevant serogroups of meningococcal disease may become a reality.

Strategies for development of universal vaccines against meningococcal serogroup B disease: the most promising options and the challenges evaluating them.

A vaccine inducing protection against most of the circulating variants of serogroup B meningococcal strains is not yet available. A number of plausible options are currently under investigation. A conjugate vaccine based on a modified capsular polysaccharide might well work, but has safety concerns from molecular mimicry between group B sialic acid and human tissue. Recently, however, the group B capsule has been shown to contain de-N-acetyl sialic acid residues that do not cross react with normal host tissues and can then be the target of bactericidal antibodies. Potentially, this polysaccharide structure could form the basis of a safe and protective group B vaccine. Outer membrane vesicles (OMVs) from Neisseria lactamica avoid the immunodominant and highly strain specific immune response against the PorA protein, and are reported to elicit cross reactive protection in mice against lethality from challenge with meningococcal group B bacteria. However, the serum antibody responses lack bactericidal activity, and the mechanisms of protection are unknown. A number of universal, cross-reactive antigens have been identified through "reverse vaccinology" and successfully tested as recombinant protein vaccines. Promising results have also been demonstrated using OMV vaccines prepared from strains engineered for upregulation of conserved, cross-reactive antigens. This approach takes advantage of experience gained with conventional wild-type OMV vaccines and the large number of new antigens identified through sequencing the genome of N. meningitidis. Initial studies show that the traditional use of detergents to decrease toxicity by extraction of lipopolysaccharides (LPS) should, if possible, be omitted in order to avoid extraction of important lipoproteins. In the absence of detergent extraction, clinical OMV formulations with acceptable toxicity may still be achieved by constructing vaccine production strains with genetically detoxified LPS. Thus, a MenB vaccine might be designed based on non-cross-reactive capsular antigens, OMV vaccines from genetically modified strains, recombinant proteins or a combination of these approaches. Given all of the recent data available and experience gained, the possibility for development of a universal vaccine for prevention of group B meningococcal disease looks promising. For evaluation of vaccine formulations relying on cross-reactive proteins, selection of strains for representation of the global epidemiological situation will be of outmost importance. Defining criteria for establishing and revising such strain collections is currently ongoing and will be a key element in developing and evaluating new protein based vaccines in the time to come.

The concept of "tailor-made", protein-based, outer membrane vesicle vaccines against meningococcal disease.

Protein-based, outer membrane vesicle (OMV) vaccines have previously proven to be efficacious against serogroup B meningococcal disease in Norway and Cuba. Currently, a public health intervention is going on in order to control a serogroup B epidemic in New Zealand. The scale-up and standardization of vaccine production required for controlling the New Zealand epidemic has allowed the establishment of large-scale GMP manufacturing for OMV vaccines. The outcome of this will be licensing of the vaccine in New Zealand and possibly other countries. The availability of licensed OMV vaccines raises the question of whether such vaccines may provide the opportunity to control other outbreaks and epidemics. For instance, such a vaccine could control a localised outbreak of group B meningococci in Normandy, France. "Tailor-made" vaccines, focusing on the sub-capsular antigens may also be considered for use in sub-Saharan Africa for the prevention of the recurrent outbreaks by serogroups A and W135 meningococci. This assumption is based on the epidemiological observation that meningococcal outbreaks in Africa are clonal and are strikingly stable regarding their phenotypic characteristics.

A non-living nasal influenza vaccine can induce major humoral and cellular immune responses in humans without the need for adjuvants.

Twenty-eight healthy adult volunteers were immunized intranasally with an inactivated whole-virus influenza vaccine based on the strain A/New Caledonia/20/99 (H1N1), either in saline or mixed with formaldehyde-inactivated Bordetella pertussis as a mucosal adjuvant, or in a thixotropic vehicle with mucoadhesive properties. After four doses, all groups of vaccinees developed significant IgG- and IgA-antibody responses, measured by ELISA, in respectively serum and nasal secretions. None of the volunteers had demonstrable hemagglutination inhibition (HAI) antibodies in serum before being immunized, whereas more than 80% of them reached HAI titers>or=40, considered protective, after immunizations. In addition, cellular immune responses, measured as significant increases in CD4+ T-cell proliferation and granzyme B-producing cytotoxic T-cells, were detected against the vaccine strain as well as against heterologous virus strains (H3N2). However, no additive effect on these responses could be demonstrated with use of B. pertussis or the thixotropic substance in the present vaccines. It appeared, actually, that the mucoadhesive vehicle containing the thixotropic substance was less efficient than were the two other formulations. An influenza vaccine made as a simple particulate formulation of inactivated virus, and given repeatedly onto the nasal mucosa, may thus be an attractive alternative to currently available vaccines.

Immunisation schedules for non-replicating nasal vaccines can be made simple by allowing time for development of immunological memory.

Mice immunised intranasally with multiple doses of outer membrane vesicles (OMVs) from group B meningococci developed antibody responses that depended on the interval between doses. High levels of antibodies in saliva and extracts of faeces were induced within 4 weeks after an OMV vaccine had been given at weekly intervals, whereas the antibody responses in these samples were negligible when given four times at 1-day or 1-h intervals, or as one large dose. Only modest responses were obtained in serum after 4 weeks, however, whether the vaccine had been given repeatedly at any schedule, including the 1-week interval, or as one dose. On the other hand, two large doses given 8 weeks apart induced booster antibody responses in both serum and secretions that matched the responses from a second series of the four smaller doses. Intranasal immunisations may thus stimulate immunological memory more rapidly in secretions than in serum. In order to secure adequate systemic responses by a minimum of doses, nasal vaccines should therefore be given at intervals longer than 4 weeks, in harmony with the intervals recommended for injectable vaccines.

Bordetella pertussis can act as adjuvant as well as inhibitor of immune responses to non-replicating nasal vaccines.

In mice immunised intranasally with an inactivated whole-virus influenza (INV) vaccine, or ovalbumin (OVA), formalin-inactivated Bordetella pertussis (Bp) augmented antibody responses to the same degree as did cholera toxin (CT) when simply being mixed with INV or OVA. In order to study possible non-carrier effects of mucosal adjuvants, mice were given Bp or CT intranasally 1 day before or 1 day after the INV vaccines. At high antigen doses, both Bp and CT had an adjuvant effect on antibodies in serum also when given 1 day after the vaccine. However, Bp and CT inhibited such antibody responses in serum and saliva when given 1 day ahead of the vaccine. This inhibitory effect was most marked at low antigen doses, i.e. when the adjuvant effect was less obvious. In that event, Bp also inhibited responses in serum and saliva when given 1 day after the INV vaccine. The inhibition of these responses may thus depend on Bp and CT themselves being strongly immunogenic, and competing with INV for the functional capacity of the mucosal immune system.

Outer membrane vesicles from Neisseria meningitidis.

Flow cytometry was used to study the expression of leukocyte adhesion molecules CD11a, CD11b, CD11c, CD14, and CD62L (L-selectin) and production of reactive oxygen species (ROS) in an ex vivo human whole-blood system stimulated with lipopolysaccharide-containing outer membrane vesicles (LPS-OMV) from N. meningitidis. Results demonstrated a dose-dependent increase in surface expression of CD11a, CD11b, CD11c and CD14 in granulocytes and monocytes (maximal at 30-120 min) upon OMV-LPS challenge, whereas CD62L expression was heavily downregulated (maximal at 30-120 min). The OMV-associated LPS was almost as potent (on a weight basis) as purified LPS from E. coli in inducing adhesion molecule modulation but the response was delayed. Upon stimulation with OMV-LPS or E. coli-LPS, the production of intracellular ROS increased in both granulocytes and monocytes when dihydroethidium (DHE, mainly reflecting superoxide anion) was used as a probe, whereas peroxynitrite production monitored with dihydrorhodamine 123 (DHR) was not significantly changed. The OMV-mediated modulation of leukocyte adhesion molecule expression and increased ROS production may certainly lead to increased entrapment of leukocytes in the microcirculation and contribute to untoward inflammatory reactions as seen in systemic meningococcal disease.

Can nonliving nasal vaccines be made to work?

Nasal vaccines consisting of nonliving particulate formulations can induce immune responses of importance for protection against infection. The most promising results have been obtained with vaccines against influenza, pertussis and group B meningococcal disease. So far, however, the results do not challenge the standing of corresponding injectable vaccines, although results of experiments in animals do indicate that effective nonliving nasal vaccines may soon be developed. This will depend on refined immunization schedules to benefit from immunological memory and on formulations to make the vaccines more accessible to the immune system by way of mucosal adjuvants or immune modulators.