Cross-Protective Potential and Protection-Relevant Immune Mechanisms of Whole Inactivated Influenza Virus Vaccines Are Determined by Adjuvants and Route of Immunization

Adjuvanted whole inactivated virus (WIV) influenza vaccines show promise as broadly protective influenza vaccine candidates. Using WIV as basis we assessed the relative efficacy of different adjuvants by carrying out a head-to-head comparison of the liposome-based adjuvants CAF01 and CAF09 and the protein-based adjuvants CTA1-DD and CTA1-3M2e-DD and evaluated whether one or more of the adjuvants could induce broadly protective immunity. Mice were immunized with WIV prepared from A/Puerto Rico/8/34 (H1N1) virus intramuscularly with or without CAF01 or intranasally with or without CAF09, CTA1-DD, or CTA1-3M2e-DD, followed by challenge with homologous, heterologous or heterosubtypic virus. In general, intranasal immunizations were significantly more effective than intramuscular immunizations in inducing virus-specific serum-IgG, mucosal-IgA, and splenic IFNγ-producing CD4 T cells. Intranasal immunizations with adjuvanted vaccines afforded strong cross-protection with milder clinical symptoms and better control of virus load in lungs. Mechanistic studies indicated that non-neutralizing IgG antibodies and CD4 T cells were responsible for the improved cross-protection while IgA antibodies were dispensable. The role of CD4 T cells was particularly pronounced for CTA1-3M2e-DD adjuvanted vaccine as evidenced by CD4 T cell-dependent reduction of lung virus titers and clinical symptoms. Thus, intranasally administered WIV in combination with effective mucosal adjuvants appears to be a promising broadly protective influenza vaccine candidate.Peer Reviewe

Construction, expression and purification of hepatitis B core mutants for structural investigations and generation of novel vaccine prototypes

Darba mērķis bija konstruēt un attīrīt dažādus hepatīta B vīrusa (HBV) nukleokapsīda proteīna (HBc) mutantus (a) strukturāliem pētījumiem un (b) jaunu vakcīnu prototipu izstrādei. HBc dimēru mijiedarbības pētījumiem ar šūnas transportproteīniem un/vai kodola poru kompleksa proteīniem uz 145 aminoskābju garā HBc (HBcΔ145) bāzes tika konstruēti mutanti: N33→R, A36→Q un R127→E. Divi pēdējie tika veiksmīgi ekspresēti un attīrīti. Abi veidoja dimērus, bet ne nukleokapsīdas, tomēr A36→Q proteīns producējās labāk un tika iegūts ar augstāku tīrības pakāpi. Jaunu vakcīnu prototipu izstrādei tika pārbaudīta HBc mutanta E77→K spēja ķīmiski saistīt Laima boreliozes izraisītājas Borrelia burgdorferi ārējās virsmas proteīnu BB0689. Tika konstruēts E77→K mutants uz 176 aminoskābju gara HBc bāzes. Izveidotais konstrukts tika ekspresēts E. coli un nukleokapsīdu formā attīrīts no šūnām. Šī struktūra bija piemērota BB0689 proteīna ķīmiskai piesaistei, un ar himērajām daļiņām tika imunizētas peles.The main purpose of this work was to generate hepatitis B core mutants for (a) structural investigations and (b) generation of novel vaccine prototypes. Three HBc mutants were constructed on basis of C-terminally truncated 145 amino acids long HBc (HBcΔ145) to investigate possible interactions between HBc dimers and cellular transportproteins. Mutants were created by substitutions of N33→R, A36→Q and R127→E. Last two were expressed and purified. Both were forming free dimers but only protein A36→Q was suitable for further investigations in HBV cellular transport due to its high purity. As for novel vaccine candidates, HBc capsid-forming mutant E77→K was tested for chemical coupling to Lyme disease agent Borrelia burgdorferi outer surface protein BB0689. Mutation was constructed on basis of 176 amino acids long HBc. Construct was expressed following purification of VLPs. Capsids were suitable for chemical coupling to BB0689, and resulting chimeric VLPs were used for the immunization

Cross-Protective Potential and Protection-Relevant Immune Mechanisms of Whole Inactivated Influenza Virus Vaccines Are Determined by Adjuvants and Route of Immunization

Adjuvanted whole inactivated virus (WIV) influenza vaccines show promise as broadly protective influenza vaccine candidates. Using WIV as basis we assessed the relative efficacy of different adjuvants by carrying out a head-to-head comparison of the liposome-based adjuvants CAF01 and CAF09 and the protein-based adjuvants CTA1 -DD and CTA1-3M2e-DD and evaluated whether one or more of the adjuvants could induce broadly protective immunity. Mice were immunized with WIV prepared from A/Puerto Rico/8/34 (RINI) virus intramuscularly with or without CAF01 or intranasally with or without CAF09, CTA1 -DD, or CTA1-3M2e-DD, followed by challenge with homologous, heterologous or heterosubtypic virus. In general, intranasal immunizations were significantly more effective than intramuscular immunizations in inducing virus-specific serum-IgG, mucosal-IgG, and splenic IFN gamma-producing CD4 T cells. Intranasal immunizations with adjuvanted vaccines afforded strong cross-protection with milder clinical symptoms and better control of virus load in lungs. Mechanistic studies indicated that non-neutralizing IgG antibodies and CD4 T cells were responsible for the improved cross-protection while IgA antibodies were dispensable. The role of CD4 T cells was particularly pronounced for CTA1-3M2e-DD adjuvanted vaccine as evidenced by CD4 T cell-dependent reduction of lung virus titers and clinical symptoms. Thus, intranasally administered WIV in combination with effective mucosal adjuvants appears to be a promising broadly protective influenza vaccine candidate.</p

Detoxified synthetic bacterial membrane vesicles as a vaccine platform against bacteria and SARS-CoV-2

Abstract The development of vaccines based on outer membrane vesicles (OMV) that naturally bud off from bacteria is an evolving field in infectious diseases. However, the inherent inflammatory nature of OMV limits their use as human vaccines. This study employed an engineered vesicle technology to develop synthetic bacterial vesicles (SyBV) that activate the immune system without the severe immunotoxicity of OMV. SyBV were generated from bacterial membranes through treatment with detergent and ionic stress. SyBV induced less inflammatory responses in macrophages and in mice compared to natural OMV. Immunization with SyBV or OMV induced comparable antigen-specific adaptive immunity. Specifically, immunization with Pseudomonas aeruginosa-derived SyBV protected mice against bacterial challenge, and this was accompanied by significant reduction in lung cell infiltration and inflammatory cytokines. Further, immunization with Escherichia coli-derived SyBV protected mice against E. coli sepsis, comparable to OMV-immunized group. The protective activity of SyBV was driven by the stimulation of B-cell and T-cell immunity. Also, SyBV were engineered to display the SARS-CoV-2 S1 protein on their surface, and these vesicles induced specific S1 protein antibody and T-cell responses. Collectively, these results demonstrate that SyBV may be a safe and efficient vaccine platform for the prevention of bacterial and viral infections

A vaccine combination of lipid nanoparticles and a cholera toxin adjuvant derivative greatly improves lung protection against influenza virus infection

This is a proof-of-principle study demonstrating that the combination of a cholera toxin derived adjuvant, CTA1-DD, and lipid nanoparticles (LNP) can significantly improve the immunogenicity and protective capacity of an intranasal vaccine. We explored the self-adjuvanted universal influenza vaccine candidate, CTA1-3M2e-DD (FPM2e), linked to LNPs. We found that the combined vector greatly enhanced survival against a highly virulent PR8 strain of influenza virus as compared to when mice were immunized with FPM2e alone. The combined vaccine vector enhanced early endosomal processing and peptide presentation in dendritic cells and upregulated co-stimulation. The augmenting effect was CTA1-enzyme dependent. Whereas systemic anti-M2e antibody and CD4+ T-cell responses were comparable to those of the soluble protein, the local respiratory tract IgA and the specific Th1 and Th17 responses were strongly enhanced. Surprisingly, the lung tissue did not exhibit gross pathology upon recovery from infection and M2e-specific lung resident CD4+ T cells were threefold higher than in FPM2e-immunized mice. This study conveys optimism as to the protective ability of a combination vaccine based on LNPs and various forms of the CTA1-DD adjuvant platform, in general, and, more specifically, an important way forward to develop a universal vaccine against influenza