Development of a Influenza A "universal" vaccine using a polymeric bacterial scaffold as a carrier of viral antigens.

PAULA ALVAREZ; VANESA ZYLBERMAN; GISELLE GHERSI; FERNANDO GOLDBAUM; NORA MATTION

Buenos Aires

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

Background and aims. Influenza is a respiratory disease that ranges in severity from subclinical infection to primary viral pneumonia, which may result in death. The most effective protection is afforded by vaccination, provided a proper matching with the circulating strains is obtained. In order to achieve a wider protective spectrum, we have taken an approach based on the highly conserved 23 amino acid extracellular domain of M2 protein (eM2) expressed as a fusion with a recombinant decameric bacterial protein (eM2-Quimera). Several studies have shown that this peptide generates a protective immune response against lethal challenge with live influenza virus. Moreover, since this peptide is highly conserved among different strains, the response generated is, in most cases, cross-protective. The present development is promising because it involves the use of a potent immunostimulatory bacterial decameric protein as a carrier, which might significantly increase the response against the eM2 peptide and therefore cross-protective capacity. Methods.  The sequence of eM2 was cloned in the vector pET11a in frame with the carrier gene. E. coli cultures were transformed with the construction.  Decameric molecules formed spontaneously through association of 10 recombinant eM2-Quimera monomers.  The fusion proteins were formulated as vaccines with different adjuvants and used to immunize 45 day-old Balb/c mice by different routes. Immune sera were collected and specific eM2 antibody levels were determined by ELISA. Vaccines containing the protean carrier alone were used as a negative control. Results. The recombinant eM2-Quimera decameric protein was expressed and purified from bacterial cells. Experimental vaccines were formulated with or without adjuvants and were administrated to mice by different routes. Mice immunized with the recombinant eM2-Quimera protein developed higher titers than the control groups and the immune responses were found to be dose dependent. Conclusions. The eM2 peptide sequences of influenza strains circulating in humans since the beginning of the last century have been highly conserved. Therefore, an eM2-Quimera vaccine is expected to enhance the presentation of the influenza antigen to the immune system and provide broad protection against multiple strains.