The emergence of H5, H7, and H9 avian influenza virus subtypes in humans reveals their
pandemic potential. Although human-to-human transmission has been limited, the genetic
reassortment of the avian and human/porcine influenza viruses or mutations in some of the
genes resulting in virus replication in the upper respiratory tract of humans could generate
novel pandemic influenza viruses. Current vaccines do not provide cross protection against
antigenically distinct strains of the H5, H7, and H9 influenza viruses. Therefore, newer vaccine approaches are needed to overcome these potential threats. We developed an eggindependent, adenovirus vector-based, multi-epitope (ME) vaccine approach using the
relatively conserved immunogenic domains of the H5N1 influenza virus [M2 ectodomain
(M2e), hemagglutinin (HA) fusion domain (HFD), T-cell epitope of nucleoprotein (TNP). and
HA α-helix domain (HαD)]. Our ME vaccine induced humoral and cell-mediated immune
responses and caused a significant reduction in the viral loads in the lungs of vaccinated
mice that were challenged with antigenically distinct H5, H7, or H9 avian influenza viruses.
These results suggest that our ME vaccine approach provided broad protection against the
avian influenza viruses. Further improvement of this vaccine will lead to a pre-pandemic
vaccine that may lower morbidity, hinder transmission, and prevent mortality in a pandemic
situation before a strain-matched vaccine becomes available.