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

LORENA A. BOADO; ANDREA PERALTA; EDUARDO A. SCODELLER; OSCAR TABOGA; PAULA ALVAREZ; NORA MATTION

Buenos Aires

Congreso; III International Clinical Virology Symposium and Advances in Vaccines.; 2010

CEMIC y Pan American Society for Clinical Virology

Background and aims.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 appear in the human population causing pandemics. In order to achieve a broad range protective vaccine against influenza A, we have taken an approach based on the ectodomain of Matrix 2 (eM2) protein, which has been shown to generate a protective immune response against lethal challenge with live influenza virus. Moreover, since this peptide is highly conserved among different strains, the immune response generated may protect multiple strains of influenza virus.  A 23mer peptide with the eM2 sequence was fused to the N-terminal of Bv glycoprotein gp64 (eM2-gp64) and displayed on the membranes of the baculovirus (Bv) particles. The proposed system has additional advantages, such as the natural activation of the immune system by Bv and the presentation of the eM2 peptide in a similar context as native virus. Methods. The sequence of eM2 was cloned into the vector pVLSUP1 (derived frompVL1393, BD Biosciences) containing the gp64 sequence plus a multiple cloning site downstream of the signal peptide. Recombinant Bv (rBv) were obtained by transfection of Sf9 cells with pVLSUP1-eM2 and the linearized Bv genome (BaculoGold). rBv particles were cloned by limiting dilution and amplified in SF9 cells. The vaccines were formulated with different adyuvants. Forty-five month old Balb/c mice were immunized by different routes. Immune sera was collected and specific eM2 antibody levels were determined by ELISA. Vaccines containing wild type Bv were used as negative controls. Results. A rBv displaying the fusion protein eM2-gp64 in the external membrane was obtained. Mice immunized with this rBv particles developed significant higher titers than the control groups and the responses were found to be dose dependent. Conclusions. The eM2 sequences of influenza virus strains circulating in humans since the beginning of the last century have been highly conserved. A vaccine based on the eM2 peptide is therefore expected to provide broad protection against new strains provided it is properly presented to the immune system, and are suitable candidates for a “universal” influenza vaccine. Challenge experiments are in course