Dengue virus (DENV) is a mosquito-borne Flavivirus that is endemic in many tropical and sub-tropical countries where the transmission vectors Aedes spp. mosquitoes resides. There are four serotypes of the virus. Each serotype is antigenically different, meaning they elicit heterologous antibodies. Infection with one serotype will create neutralizing antibodies to the serotype. Cross-protection from other serotypes is not long term, instead heterotypic infection can cause severe disease. This review will focus on the innate immune response to DENV infection and the virus evasion of the innate immune system by escaping recognition or inhibiting the production of an antiviral state. Activated innate immune pathways includes type I interferon, complement, apoptosis, and autophagy, which the virus can evade or exploit to exacerbate disease. It is important to understand out how the immune system reacts to infection and how the virus evades immune response in order to develop effective antivirals and vaccines.

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Oil-in-water (O/W) nanoemulsion-based vaccine adjuvants such as MF59® are often used in seasonal and pandemic influenza vaccines. However, vaccines containing nanoemulsions require cold chain for storage and are sensitive to accidental freezing. We explored the feasibility of developing dry powders of vaccines adjuvanted with MF59 or AddaVax™, a preclinical grade nanoemulsion that has the same composition and droplet size as MF59, by thin-film freeze-drying (TFFD). AddaVax alone was successfully converted from a liquid to dry powders by TFFD using trehalose as a stabilizing agent while maintaining the droplet size distribution of the AddaVax when reconstituted, whereas subjecting the same AddaVax composition to conventional shelf freeze-drying led to significant aggregation or fusion. TFFD was then applied to convert liquid AddaVax-adjuvanted vaccines containing either model antigens such as ovalbumin and lysozyme, mono-, bi-, and tri-valent recombinant hemagglutinin (rHA) protein-based H1 and/or H3 (universal) influenza vaccine candidates, as well as the MF59-containing Fluad® Quadrivalent influenza vaccine to dry powders. Antigens, stabilizing agents, and buffer showed different effects on the physical properties of the vaccines (e.g., mean particle size and particle size distribution) after subjected to TFFD, but the integrity and hemagglutination activity of the rHA antigens did not significantly change and the immunogenicity of reconstituted influenza vaccine candidates was preserved when evaluated in BALB/c mice. The vaccine dry powder was not sensititve to repeated freezing-and-thawing, in contrast to its liquid counterpart. It is concluded that TFFD can be applied to convert vaccines containing MF59 or an nanoemulsion with the same composition and droplet size as MF59 from liquid to dry powders while maintaining the immunogencity of the vaccines, and it may be used to prepare dry powders of multivalent universal influenza vaccines.

Any potential dengue virus (DENV) vaccine needs to elicit protective immunity against strains from all four serotypes to avoid potential antibody dependent enhancement (ADE). In this study, four independent DENV envelope (E) glycoproteins were generated using wild-type E sequences from viruses isolated between 1943 to 2006 using computationally-optimized broadly reactive antigen (COBRA) methodology. COBRA and wild-type E antigens were expressed on the surface of subvirion viral particles (SVPs). Four separate wild-type E antigens were used for each serotype. Mice vaccinated with wild-type DENV SVPs had anti-E IgG antibodies that neutralized serotype specific viruses. COBRA DENV SVPs elicited a broader breadth of antibodies that neutralized strains across all four serotypes. Two COBRA DENV vaccine candidates that elicited the broadest breadth of neutralizing antibodies in mice were used to vaccinate rhesus macaques (Macca mulata) that were either immunologically naïve to any DENV serotype or were had pre-existing antibodies to DENV. Antibodies elicited by COBRA DENV E immunogens neutralized all 12 strains of DENV in vitro, which was comparable to antibodies elicited by a tetravalent wild-type E SVP vaccination mixture. Therefore, using a single DENV COBRA E protein can elicit neutralizing antibodies against strains representing all four serotypes of DENV in both naïve and dengue pre-immune populations. Importance Dengue virus infects millions of people living in the tropical areas of the world. Dengue induced diseases can range from mild to severe with death. An effective vaccine will need to neutralize viruses from all four serotypes of dengue without induced enhanced disease. A dengue E vaccine candidate generated by computationally optimized broadly reactive antigen algorithms elicits broadly neutralizing protection for current circulating strains from all four serotypes regardless of immune status. Most Dengue vaccines in development formulate four separate components based on prM-E from a wild type strain representing each serotype. Designing a monovalent vaccine that elicits protective immunity against all four serotypes is an effective and economical strategy

Each year, new influenza virus vaccine formulations are generated to keep up with continuously circulating and mutating viral variants. A next-generation influenza virus vaccine would provide long-lasting, broadly-reactive immune protection against current and future influenza virus strains for both seasonal and pre-pandemic viruses. Next generation immunogens were designed using computationally optimized broadly reactive antigen (COBRA) methodology to protect against a broad range of strains over numerous seasons. Novel HA and NA amino acid sequences were derived from multilayered consensus sequence alignment for multiple subtypes of influenza. This multivalent formulation was hypothesized to elicit broadly protective immune responses against both seasonal and pre-pandemic influenza viruses. Mice were vaccinated with multivalent mixtures of HA and NA (H1, H2, H3, H5, H7, N1, N2) proteins. Multivalent COBRA vaccinations elicited antibodies that recognized a broad panel of strains and vaccinated mice were protected against viruses representing multiple subtypes. This is a promising candidate for a universal influenza vaccine that elicits protective immune responses against seasonal and pre-pandemic strains over multiple seasons.