Anti-Influenza Oral Vaccines Derived from Attenuated Salmonella

Oral gene delivery vectors, such as those derived from attenuated strains, have shown great promise in the development of oral vaccines against various human diseases. For example, the -based Ty21a vaccine stimulates local, cellular, and systemic immunity against typhoid fever-causing simultaneously, demonstrating its unique and powerful triple-action effect that is not associated with parenteral vaccines. Influenza infection, caused by seasonal and pandemic influenza viruses, can potentially lead to large numbers of deaths in humans and animals, as well as significant financial losses. It is a global public health priority to develop better and more effective vaccines against strains of influenza viruses, especially those circulating avian influenza virus strains with pandemic potential. In this chapter, we first review recent research in understanding the ability of -based vectors to perform efficient gene transfer and induce strong immune responses. Moreover, we also describe several representative examples of -based anti-influenza virus vaccines in recent studies, as additional vectors with different strategies for delivery and expression of different factors to enhance their ability for gene delivery and immune responses are being explored as oral vaccine candidates. Finally, we discuss prospects for developing attenuated expressing different influenza virus antigens against various strains of influenza viruses, including the H5N1 avian influenza viruses.