T Cell epitope mapping of the E-protein of West Nile virus in BALB/c mice

West Nile virus (WNV) is a zoonotic virus, which is transmitted by mosquitoes. It is the causative agent of the disease syndrome called West Nile fever. In some human cases, a WNV infection can be associated with severe neurological symptoms. The immune response to WNV is multifactorial and includes both humoral and cellular immunity. T-cell epitope mapping of the WNV envelope (E) protein has been performed in C57BL/6 mice, but not in BALB/c mice. Therefore, we performed in BALB/c mice a T-cell epitope mapping using a series of peptides spanning the WNV envelope (E) protein. To this end, the WNV-E specific T cell repertoire was first expanded by vaccinating BALB/c mice with a DNA vaccine that generates subviral particles that resemble West Nile virus. Furthermore, the WNV structural protein was expressed in Escherichia coli as a series of overlapping 20-mer peptides fused to a carrier-protein. Cytokine-based ELISPOT assays using these purified peptides revealed positive WNV-specific T cell responses to peptides within the different domains of the E-protein

Universal M2 ectodomain-based influenza A vaccines: preclinical and clinical developments

Influenza vaccines used today are strain specific and need to be adapted every year to try and match the antigenicity of the virus strains that are predicted to cause the next epidemic. The strain specificity of the next pandemic is unpredictable. An attractive alternative approach would be to use a vaccine that matches multiple influenza virus strains, including multiple subtypes. In this review, we focus on the development and clinical potential of a vaccine that is based on the conserved ectodomain of matrix protein 2 (M2) of influenza A virus. Since 1999, a number of studies have demonstrated protection against influenza A virus challenge in animal models using chemical or genetic M2 external domain (M2e) fusion constructs. More recently, Phase I clinical studies have been conducted with M2e vaccine candidates, demonstrating their safety and immunogenicity in humans. Ultimately, and possibly in the near future, efficacy studies in humans should provide proof that this novel vaccine concept can mitigate epidemic and even pandemic influenza A virus infections

Universal influenza A vaccine: Optimization of M2-based constructs

AbstractM2e is the external domain of the influenza A M2-protein. It is minimally immunogenic during infection and conventional vaccination, which explains in part its striking sequence conservation across all human influenza A strains. Previous research has shown that when M2e is linked to an appropriate carrier such as hepatitis B virus core (HBc) particles, it becomes highly immunogenic, eliciting antibodies that fully protect mice against a potentially lethal virus infection. Different M2e-HBc particles and adjuvants suitable for human use were compared for induction of protective immunity. Strong immunogenicity and full protection were obtained after either intraperitoneal or intranasal administration. The most protective particle contained three consecutive M2e-copies linked to the N-terminus of HBc. Although HBc is highly immunogenic, the optimized M2e-HBc vaccine induced an anti-M2e antibody titer even higher than that of anti-HBc

Detection of cellular and humoral immune response following pDNA-based vaccination.

<p>IFN-γ production by (a) CD4-depleted and (c) CD8-depleted splenocytes after stimulation with purified recombinant GST tagged E-protein derived peptides. The WNV E-protein specific T-cell repertoire in BALB/c mice was expanded by two DNA vaccinations. Splenocytes obtained two weeks after the boost were stimulated with different recombinant GST tagged E-protein derived peptides and the numbers of cells producing IFN-γ were determined via ELISPOT. (b) Detection of serum IgG1 and IgG2a titers to the WNV E-protein two weeks after the boost via ELISA.</p

M2e-based universal influenza A vaccine

Human influenza causes substantial morbidity and mortality. Currently, licensed influenza vaccines offer satisfactory protection if they match the infecting strain, but they come with significant drawbacks. These vaccines are derived from prototype viruses, containing the hemagglutinin of influenza viruses that are likely to cause the next epidemic. Their usefulness against a future pandemic, however, remains problematic. A vaccine based on the ectodomain of influenza matrix protein 2 (M2e) could overcome these drawbacks. M2e is highly conserved in both human and avian influenza A viruses. The low immunogenicity against natural M2e can be overcome by fusing M2e to an appropriate carrier such as Hepatitis B virus-derived virus-like particles. Such chimeric particles can be produced in a simple and safe bacterial expression system, requiring minimal biocontainment, and can be obtained in a pure form. Experiments in animal models have demonstrated that M2e-based vaccines induce protection against a lethal challenge with various influenza A virus subtypes. Furthermore, the production and use of an effective M2e-vaccine could be implemented at any time regardless of seasonality, both in an epidemic aswell as in a pandemic preparedness program. In animal models, M2e-vaccines administered parenterally or intranasally protect against disease and mortality following challenge with various influenza A strains. Adjuvants suitable for human use improve protection, which correlates with higher anti-M2e antibody responses of defined subtypes. Recently, Phase I clinical studies with M2e-vaccines have been completed, indicating their safety and immunogenicity. Further clinical development of this universal influenza A vaccine candidate is being pursued in order to validate its protective efficacy in humans