Nanoparticle Vaccine for Avian Influenza Virus: A Challenge Study against Highly Pathogenic H5N2 Subtype

We used a platform of self-assembling protein nanoparticles (SAPNs) to develop a self-adjuvanted vaccine for avian influenza virus (AIV). A SAPNs named SA-MC-Penn was designed to display the ectodomain of influenza matrix protein 2 (M2e) as a tetramer and Helix C (Hel C) of hemagglutinin as a trimer. Flagellin domains
expressed within a peptide chain were co-assembled into the SAPN core serving as a built-in adjuvant. SA-MC-Penn was administered every two weeks for three times via the intramuscular (IM) or eye drop (ED) routes in chickens starting at four-weeks of age. Sera were collected from immunized chickens at twelve-weeks of age prior to challenge with a highly pathogenic (HP) H5N2 strain of AIV. ELISA results demonstrated that high titers of serum antibodies were induced in the IM immunized SAPNs. Upon challenge with HP AIV, 63 % and 30% of chickens the SAPNs IM and SAPN ED groups, respectively, survived. A reduction in challenge virus shedding from oropharyngeal swabbings of the SAPNs IM vaccinates was observed on days two and 14-post challenge. These results show the SAPNs vaccine prototype was partially protective against HPAIV.