Development of a broad protection Influenza A vaccine based on external domain of Matrix 2 (eM2) protein

L. A. BOADO; A. PERALTA; E. A. SCODELLER; O. TABOGA; P. ALVAREZ; N. MATTION

Simposio; III International Clinical Virology Symposium and Advances in Vaccines; 2010

CEMIC y Pan American Society for Clinical Virology

Development of protective vaccines against influenza virus has proven difficult due to the high mutation rate of the surface proteins. Moreover, occasionally novel influenza strains containing new hemaglutinin (HA) and/or neuraminidase (NA) genes acquired from animal influenza viruses appear in the human population (?genetic shift?) causing pandemics.In order to achieve a wide range protection vaccine against influenza A, we have taken an approach based on Matrix 2 (M2) protein of influenza. The vaccine targets the highly conserved 23 amino acid extracellular domain of M2 protein expressed as display on the membranes of the baculovirus (Bv) particle. This display is obtained the fusion of this 23 mer peptide to the N-terminal of Bv glycoprotein gp64 (eM2-gp64). Several studies have shown that immunization with this peptide generates a protective immune response against lethal challenge with influenza virus. Moreover, since this peptide is highly conserved among different strains of influenza A, the response generated is, in most cases, cross-protective. Additionally, the proposed system combines others advantages like the natural activation of the immune system by Bv and the presentation of this peptide in a similar influenza virus context. Cloning the coding sequence of eM2 in the transfer vector pVLSUP1. This is a pVL1393 vector (BD Biosciences) with the gp64 sequence cloned plus a multiple cloning site between the signal peptide and the mature sequence of the protein. Obtaining of recombinant Bv by transfection of Sf9 cells with pVLSUP1- eM2 plus linearized DNA Baculovirus of AcNPV (BaculoGold, BD Biosciences). Cloning, amplification and production of recombinant virus particles. Obtaining of wild type Bv to be used as control. Formulation of vaccine candidates with different adyuvants. Immunization of 45-60 years olds Balb/c mice by different routes. Collection of sera and determination of specific eM2 antibodies levels by ELISA.Results. We have obtained recombinant Bv expressing the fusion protein eM2-gp64 in their membranes. We formulated experimental vaccines in the presence or absence of different adjuvants and were administrated to mice by different routes. Mice immunized with the recombinant Bv particles developed greater titers than the control groups and this response was dose dependent. The M2 sequence in influenza strains circulating in humans since the beginning of the last century has been highly conserved. Then, an M2-based vaccine is therefore expected to broadly protect against new strains and could potentially be used as a ?universal? vaccine against influenza A.