Host-targeted self-attenuated influenza virus as an effective nasal spray vaccine in aged population

Abstract The elderly are at high risk for influenza infection and its complication. However, current inactivated influenza vaccines are often modestly immunogenic and show low protective immunity in the elderly, due to immunosenescence. New approaches are urgently needed for developing effective vaccines against influenza for the elderly. In current study, we have constructed new recombinant influenza viruses, named host-targeted self-attenuated influenza viruses (SAIVs), which can express functional mammalian species-specific artificial microRNAs (amiRNAs). The expression of these amiRNAs can inhibit expression of some host factors critical for influenza replication, and therefore the resultant recombinant influenza viruses are replication restricted and attenuated in the host cells. One of these SAIVs, which can express an amiRNA that inhibits expression of the host cellular Cdc2-like kinase 1 (CLK1), was produced in embryonic chicken eggs and evaluated in an aged mouse model of influenza infection. It elicited robust antibody and T cell responses against influenza virus and demonstrated significantly protective efficacy against lethal infection with wild type influenza virus H1N1 PR8 after single dose of intranasal vaccination. Our research finding provided a proof of concept that the new host targeted self-attenuated influenza virus can be further used as an effective vaccine against influenza in aged population. Supported by a research grant from National Institute of Allergy and Infectious Diseases (AI133207).