Advances in the development of vaccines against human influenza

LORENA BOADO; ANDREA PERALTA; DIEGO CARGNELUTTI; EDUARDO SCODELLER; OSCAR TABOGA; PAULA ALVAREZ; NORA MATTION

Punta del Este

Workshop; International Course ¨Molecular Biology of Viral Diseases¨; 2011

Facultad de Ciencias de la Universidad de la República y Réseau International des Institus Pasteur

Current seasonal vaccines for the prevention of influenza are effective to neutralize homologous infections, generating protective antibodies against the major envelope glycoproteins hemagglutinin (HA) and neuraminidase, but their ability to cover hetero-subtypical strains is variable or absent. Given the high genetic variability of this virus, the vaccine strains must be updated annually. In the context of a potential pandemic, two major health issues have been highlighted: the provision of sufficient amount vaccine doses, and the necessity of broader hetero-subtypical coverage. Regarding the former issue, our laboratory is optimizing the production of vaccines based on recombinant HA (rHA), produced through the baculovirus/insect cells expression system. The sequences of several HA genes have been cloned in the transfer vector pVL1393 and cotransfected in Sf9 cells with the linearized genomic AcNPV Bv DNA (BaculoGold, BD). The rHAs have been characterized by SDS-PAGE and Western Blot. It is worth mentioning, that the use of the Bv expression system has been approved by the FDA for production of pandemic vaccines based on HA antigens, and given the lack of local production of influenza vaccines, this technology might enable a safe and rapid scalable system to cover local needs. Regarding the second issue, in order to achieve a wide range protection vaccine, we have developed an approach based on the Matrix 2 (M2) protein of influenza. The vaccine candidate targets the highly conserved extracellular domain of M2 protein (eM2) expressed as display on the membranes of rBv particles. This display is obtained through the fusion of the 23 mer peptide to the N-terminal of the Bv glycoprotein gp64 (eM2-gp64). We have already obtained rBvs expressing the fusion protein eM2-gp64 in their membranes, which have been used in immunization assays. Mice immunized with rBvs/eM2 particles developed higher antibody titers than the control groups and this response was dose dependent. Considering that the M2 sequences of influenza strains circulating in humans since the beginning of the last century have been highly conserved, we expect that an M2-based vaccine will generate broader protection against new emerging strains and could potentially be used as a ?universal? vaccine against influenza A.