Construction and evaluation of an influenza A virus vaccine based on a M2e-modified alphavirus

Influenza A virus belongs to the family Orthomyxoviridae and causes respiratory infection in infected humans and other vertebrate species including swine, birds, horses and dogs. The virus has hemagglutinin (HA) and neuraminidase (NA) as its surface glycoproteins, which mediate virus entry into host cells (HA) and virion release following budding (NA). The virus experiences continual genetic and antigenic changes (antigenic drift and antigenic shift), which over time results in the evolution of new epidemic strains. Consequently, it is necessary to produce new vaccines against the influenza virus on an annual basis. The seasonal vaccines have drawbacks, including delays in the production of vaccines and distribution, periodic vaccine failure resulting from use of vaccine strains that do not match the strains circulating in the population, and poor induction cross-protective immunity against various strains of influenza. To overcome these problems there is a need to replace the HA/NA antigens of vaccine preparations with an alternative antigen that is highly conserved in nature, does not experience antigenic drift over time, and is capable of inducing cross-protective immunity against many influenza A virus subtypes and strains. The M2 protein has been investigated as a potential vaccine antigen for influenza A virus and serves as the focus of this project.

Here we describe the construction and characterization of a recombinant Sindbis virus that expresses the N-terminal fragment of M2 (M2e) on its surface. This virus, designated E2S1-M2e, was shown to be viable and infectious, to express M2e on the virion surface in a form that reacts with an M2e-specific monoclonal antibody, to induce antibodies against M2e when administered to mice through intranasal and subcutaneous routes, and to protect mice against a lethal challenge with a mouse-adapted strain of influenza A virus PR/8/34/H1N1.