Fig. 1. Adenovirus vector-based vaccine strategy for influenza.

This process involves identification of appropriate immunogen/s that needed to be incorporated in an adenovirus vector. For example, hemagglutinin (HA) and nucleoprotein (NP) serve as excellent immunogens for influenza viruses. The gene of interest can be amplified from RNA isolated from influenza virus infected cells or embryonated eggs by reverse transcriptase PCR (RT-PCR). Alternately, the codon-optimized gene can be synthesized if the sequence is known. The gene of interest under the control of an appropriate promoter and a polyadenylation site is required to be cloned into a shuttle vector in order to generate adenovirus vector carrying the gene/s of interest. The adenovirus vector is characterized for expression of the appropriate immunogen/s followed by the preparation of virus stocks in a certified cell line. Immunogenicity and vaccine efficacy will then be tested in appropriate animal models while making plans for a large scale vector production using bioreactors. The vector virus isolated from bioreactor/s is processed for virus purification and concentration followed by vaccine formulation and dispensing. This vaccine is now ready for testing in the animal species it is intended for. Adenovirus vector-based vaccine needs to undergo Phase 1 to III clinical trials before it could be distributed for human use.