A clade 1 sequence of H5 haemaglutinin from an Asian Avian H5N1 isolate was used as a the template to chemically synthetize a codon optimized version for expression in insect cells. A single clone was chosen for expression optimization and changes were introduced in order to maximize the amount of protein to be produced and to resemble another sequence demonstrated to be present in an isolate causing disease in Humans.
Preliminary analysis at lab scale have shown promising yields of the haemaglutinin using an activity titration assay and an ELISA-based detection method. Optimization of the cell seeding, MOI, and time of harvest have provided valuable data to ensure sufficient production of the protein compatible with scale up application.
In order to test the biological activity of the expressed protein and its ability to trigger an immune response, oil/water emulsions of different amounts of the protein were administered to SPF chickens and antibodies levels were detected using an ELISA-based system and HI titration. Both approaches were able to demonstrate seroconvertion and a dose-response curve was observed among the different doses. Altogether, results support the feasibility of the genetic contruct and the expression platform to produce bulk amounts of protein which could be used for different purposes
