Double-Layered M2e-NA Nanoparticles Induce Broad Protection Against Different Influenza Viruses in Mice

The development of a universal influenza vaccine is an ideal strategy to eliminate public health threats from influenza epidemics and pandemics. Influenza conserved structures are outstanding immunogens for such a vaccine. Layered protein nanoparticles composed of well-designed conserved influenza structures have improved immunogenicity with new physical and biochemical features. We constructed and purified structure-stabilized influenza matrix protein 2 ectodomain (M2e) and M2e-neuraminidase fusion proteins (M2e-NAs). We produced double-layered M2e-NA protein nanoparticles by chemical crosslinking M2e-NA onto M2e nanoparticle surfaces. Immunizations with these protein nanoparticles induced immune protection against influenza viruses with homologous and heterosubtypic NA in mice. Double-layered M2e-NA protein nanoparticles induced higher levels of humoral and cellular responses compared with their comprising protein mixture or M2e nanoparticles. In addition, the layered M2e-NA protein nanoparticle group demonstrated strong cytotoxic T cell responses. We also found that antibody responses contributed to heterosubtypic influenza viral immune protection. The protective immunity was long-lasting. To favorite rapid distribution and convenient administration of a universal influenza vaccine, we incorporated the FliC-adjuvanted M2e-NA nanoparticles into logistically simple microneedle patches (MNPs) for skin vaccination in mice. The nanoparticle MNPs significantly increased M2e and NA-specific antibody levels, the numbers of germinal center B cells, and IL-4 secreting splenocytes. MNPs incorporating the double-layered nanoparticles protected mice against homologous and heterosubtypic influenza viruses. Our results demonstrated that M2e-NA nanoparticles could be developed into a standalone or synergistic component of a universal influenza vaccine strategy. MNP skin vaccination can logistically simplify the vaccines for extensive distribution and administration

Strategies Targeting Hemagglutinin as a Universal Influenza Vaccine

Influenza virus has significant viral diversity, both through antigenic drift and shift, which makes development of a vaccine challenging. Current influenza vaccines are updated yearly to in- clude strains predicted to circulate in the upcoming influenza season, however this can lead to a mismatch which reduces vaccine efficacy. Several strategies targeting the most abundant and im- munogenic surface protein of influenza, the hemagglutinin (HA) protein, have been explored. These strategies include stalk-directed, consensus-based, and computationally derived HA immunogens. In this review, we explore vaccine strategies which utilize novel antigen design of the HA protein to improve cross-reactive immunity for development of a universal influenza vaccine

The challenges of creating a universal influenza vaccine

The lack of population immunity to the periodically emerging pandemic influenza strains makes influenza infection especially dangerous. The fragmented nature of the influenza virus genome contributes to the formation of influenza virus reassortants containing genomic fragments from different strains. This mechanism is the main reason for the natural influenza virus antigenic diversity as well as for the occurrence of influenza pandemics. Vaccination is the best measure to prevent the spread of influenza infection, but the efficacy of existing vaccines is not sufficient, especially for the elderly and small children. Specific immunity, developed after disease or immunization, poorly protects against infection by influenza viruses of another subtype. In this regard, there is an urgent need for a more effective universal influenza vaccine that provides a long-lasting broad cross-protective immunity, and is able to protect against influenza A and B viruses of all known subtypes. The basic approaches to as well as challenges of creating such a vaccine are discussed in this review.The lack of population immunity to the periodically emerging pandemic influenza strains makes influenza infection especially dangerous. The fragmented nature of the influenza virus genome contributes to the formation of influenza virus reassortants containing genomic fragments from different strains. This mechanism is the main reason for the natural influenza virus antigenic diversity as well as for the occurrence of influenza pandemics. Vaccination is the best measure to prevent the spread of influenza infection, but the efficacy of existing vaccines is not sufficient, especially for the elderly and small children. Specific immunity, developed after disease or immunization, poorly protects against infection by influenza viruses of another subtype. In this regard, there is an urgent need for a more effective universal influenza vaccine that provides a long-lasting broad cross-protective immunity, and is able to protect against influenza A and B viruses of all known subtypes. The basic approaches to as well as challenges of creating such a vaccine are discussed in this review

Production and purification of chimeric HBc virus-like particles carrying influenza virus LAH domain as vaccine candidates

Background: The lack of a universal influenza vaccine is a global health problem. Interest is now focused on structurally conserved protein domains capable of eliciting protection against a broad range of influenza virus strains. The long alpha helix (LAH) is an attractive vaccine component since it is one of the most conserved influenza hemagglutinin (HA) stalk regions. For an improved immune response, the LAH domain from H3N2 strain has been incorporated into virus-like particles (VLPs) derived from hepatitis B virus core protein (HBc) using recently developed tandem core technology. Results: Fermentation conditions for recombinant HBc-LAH were established in yeast Pichia pastoris and a rapid and efficient purification method for chimeric VLPs was developed to match the requirements for industrial scale-up. Purified VLPs induced strong antibody responses against both group 1 and group 2 HA proteins in mice. Conclusion: Our results indicate that the tandem core technology is a useful tool for incorporation of highly hydrophobic LAH domain into HBc VLPs. Chimeric VLPs can be successfully produced in bioreactor using yeast expression system. Immunologic data indicate that HBc VLPs carrying the LAH antigen represent a promising universal influenza vaccine component

Influenza nucleoprotein delivered with aluminium salts protects mice from an influenza virus that expresses an altered nucleoprotein sequence

Influenza virus poses a difficult challenge for protective immunity. This virus is adept at altering its surface proteins, the proteins that are the targets of neutralizing antibody. Consequently, each year a new vaccine must be developed to combat the current recirculating strains. A universal influenza vaccine that primes specific memory cells that recognise conserved parts of the virus could prove to be effective against both annual influenza variants and newly emergent potentially pandemic strains. Such a vaccine will have to contain a safe and effective adjuvant that can be used in individuals of all ages. We examine protection from viral challenge in mice vaccinated with the nucleoprotein from the PR8 strain of influenza A, a protein that is highly conserved across viral subtypes. Vaccination with nucleoprotein delivered with a universally used and safe adjuvant, composed of insoluble aluminium salts, provides protection against viruses that either express the same or an altered version of nucleoprotein. This protection correlated with the presence of nucleoprotein specific CD8 T cells in the lungs of infected animals at early time points after infection. In contrast, immunization with NP delivered with alum and the detoxified LPS adjuvant, monophosphoryl lipid A, provided some protection to the homologous viral strain but no protection against infection by influenza expressing a variant nucleoprotein. Together, these data point towards a vaccine solution for all influenza A subtypes

Development of universal influenza vaccines targeting conserved viral proteins

Vaccination is still the most efficient way to prevent an infection with influenza viruses. Nevertheless, existing commercial vaccines face serious limitations such as availability during epidemic outbreaks and their efficacy. Existing seasonal influenza vaccines mostly induce antibody responses to the surface proteins of influenza viruses, which frequently change due to antigenic shift and or drift, thus allowing influenza viruses to avoid neutralizing antibodies. Hence, influenza vaccines need a yearly formulation to protect against new seasonal viruses. A broadly protective or universal influenza vaccine must induce effective humoral as well as cellular immunity against conserved influenza antigens, offer good protection against influenza pandemics, be safe, and have a fast production platform. Nanotechnology has great potential to improve vaccine delivery, immunogenicity, and host immune responses. As new strains of human epidemic influenza virus strains could originate from poultry and swine viruses, development of a new universal influenza vaccine will require the immune responses to be directed against viruses from different hosts. This review discusses how the new vaccine platforms and nanoparticles can be beneficial in the development of a broadly protective, universal influenza vaccine

Steps toward a Universal Influenza Vaccine: Research Models and Comparison of Current Approaches

The ability of influenza virus to adapt to various species and evade natural immunity makes the ubiquitous pathogen particularly difficult to eradicate. Annual reformulation of influenza vaccines is costly and time-consuming and has varying efficacy against influenza virus strains. Therefore, worldwide efforts aim to develop a universal influenza vaccine to prevent potential healthcare emergencies such as pandemic influenza threats, such as the 1918 Spanish Flu and pandemic Swine Flu of 2009. Efficacy of a universal influenza vaccine must overcome current challenges with subtype diversity, antigenic drift, and adequately protect against emerging reassortants from both environmental and agricultural sources. Furthermore, the manufacturing and production of vaccines largely influence the effectiveness of a vaccine and technological advancements may soon rival current vaccine strategies. This review discusses the evolution and diversity of influenza viruses, how viral glycoprotein hemagglutinin plays a dominant role in influenza surveillance and assessment of protection and compares the methodologies of current and upcoming vaccine options. While the obstacles remain daunting, growing knowledge of influenza evolution and immunity may lead to more viable candidates that protect against broader varieties of influenza viruses and help prevent future international health crises

Novel Platforms for the Development of a Universal influenza vaccine

Despite advancements in immunotherapeutic approaches, influenza continues to cause severe illness, particularly among immunocompromised individuals, young children, and elderly adults. Vaccination is the most effective way to reduce rates of morbidity and mortality caused by influenza viruses. Frequent genetic shift and drift among influenzavirus strains with the resultant disparity between circulating and vaccine virus strains limits the effectiveness of the available conventional influenza vaccines. One approach to overcome this limitation is to develop a universal influenza vaccine that could provide protection against all subtypes of influenza viruses. Moreover, the development of a novel or improved universal influenza vaccines may be greatly facilitated by new technologies including virus-like particles, T-cell-inducing peptides and recombinant proteins, synthetic viruses, broadly neutralizing antibodies, and nucleic acid-based vaccines. This review discusses recent scientific advances in the development of next-generation universal influenza vaccines.Funding Agencies|GlaxoSmithKline Biologicals SA; Marie-Curie IEF grant SAMUFLU FP7-PEOPLE-IEF [626283]; Marie-Curie ITN grant HOMIN FP7-PEOPLE-ITN [626283]</p

A Research and Development (R&D) roadmap for influenza vaccines: Looking toward the future

Improved influenza vaccines are urgently needed to reduce the burden of seasonal influenza and to ensure a rapid and effective public-health response to future influenza pandemics. The Influenza Vaccines Research and Development (R&D) Roadmap (IVR) was created, through an extensive international stakeholder engagement process, to promote influenza vaccine R&D. The roadmap covers a 10-year timeframe and is organized into six sections: virology; immunology; vaccinology for seasonal influenza vaccines; vaccinology for universal influenza vaccines; animal and human influenza virus infection models; and policy, finance, and regulation. Each section identifies barriers, gaps, strategic goals, milestones, and additional R&D priorities germane to that area. The roadmap includes 113 specific R&D milestones, 37 of which have been designated high priority by the IVR expert taskforce. This report summarizes the major issues and priority areas of research outlined in the IVR. By identifying the key issues and steps to address them, the roadmap not only encourages research aimed at new solutions, but also provides guidance on the use of innovative tools to drive breakthroughs in influenza vaccine R&D.publishedVersio

Single-Dose Mucosal Immunization with a Candidate Universal Influenza Vaccine Provides Rapid Protection from Virulent H5N1, H3N2 and H1N1 Viruses

The sudden emergence of novel influenza viruses is a global public health concern. Conventional influenza vaccines targeting the highly variable surface glycoproteins hemagglutinin and neuraminidase must antigenically match the emerging strain to be effective. In contrast, "universal" vaccines targeting conserved viral components could be used regardless of viral strain or subtype. Previous approaches to universal vaccination have required protracted multi-dose immunizations. Here we evaluate a single dose universal vaccine strategy using recombinant adenoviruses (rAd) expressing the conserved influenza virus antigens matrix 2 and nucleoprotein.In BALB/c mice, administration of rAd via the intranasal route was superior to intramuscular immunization for induction of mucosal responses and for protection against highly virulent H1N1, H3N2, or H5N1 influenza virus challenge. Mucosally vaccinated mice not only survived, but had little morbidity and reduced lung virus titers. Protection was observed as early as 2 weeks post-immunization, and lasted at least 10 months, as did antibodies and lung T cells with activated phenotypes. Virus-specific IgA correlated with but was not essential for protection, as demonstrated in studies with IgA-deficient animals.Mucosal administration of NP and M2-expressing rAd vectors provided rapid and lasting protection from influenza viruses in a subtype-independent manner. Such vaccines could be used in the interval between emergence of a new virus strain and availability of strain-matched vaccines against it. This strikingly effective single-dose vaccination thus represents a candidate off-the-shelf vaccine for emergency use during an influenza pandemic