A combinatory mucosal vaccine against influenza and botulism

Botulinum neurotoxins (BoNTs) are the most poisonous substances known in nature and cause the life-threatening botulism. Currently, there is no FDA licensed botulism vaccine available for public use. Influenza is still an important problem for public health and current influenza vaccines are not optimal for protection against seasonal and potential pandemic influenza. Influenza virus is a negative, segmented RNA virus without DNA intermediate. This makes it safer as a vaccine delivery vector than most DNA viruses that have potential to integrate their genetic elements into host genomes. We hypothesize that a live-attenuated influenza virus expressing botulinum antigens can be developed to a dual use vaccine against both botulism and influenza. Based on influenza virus H1N1 PR8, an engineered influenza viral vector with a 2A cleavage site on NA, was constructed. Using this vector, we generated a recombinant influenza virus, PR8/HC50-rbsd, expressing the receptor binding subdomain of the heavy chain C-terminal receptor binding domain (HC50-rbsd) from BoNT/A. We tested the growth characters of the recombinant PR8/HC50-rbsd virus in chicken eggs and Madin-Darby Canine Kidney epithelial cells (MDCK), and showed that it can be produced to a titer of 5×10E6 plaque forming units/ml in chicken eggs and MDCK cells. Subsequently, mice intranasally vaccinated with the PR8/HC50-rbsd virus conferred protection against challenge with lethal doses of active BoNT/A toxin and wild type H1N1 PR8 influenza virus. Our results demonstrated that it is possible to develop a dual purpose nasal vaccine against both botulism and influenza.