Despite an intensive
vaccine program
influenza infections remain a major health problem, due to the viruses' ability to change its envelope
glycoprotein hemagglutinin (HA), through shift and drift, permitting
influenza to escape protection induced by current
vaccines or natural immunity. Recently a new variant, H7N9, has emerged in China causing global concern. First, there have been more than 130 laboratory-confirmed human
infections resulting in an alarmingly high death rate (32.3%). Second, genetic changes found in H7N9 appear to be associated with enabling
avian influenza viruses to spread more effectively in mammals, thus transmitting
infections on a larger scale. Currently, no
vaccines or drugs are effectively able to target H7N9. Here, we report the rapid development of a synthetic consensus
DNA vaccine (pH7HA) to elicit potent protective immunity against the H7N9 viruses. We show that pH7HA induces broad antibody responses that bind to divergent HAs from multiple new members of the H7N9 family. These antibody responses result in high-titer HAI against H7N9. Simultaneously, this
vaccine induces potent polyfunctional effector CD4 and CD8T cell memory responses. Animals vaccinated with pH7HA are completely protected from H7N9 virus
infection and any morbidity associated with lethal challenge. This study establishes that this synthetic consensus
DNA vaccine represents a new tool for targeting emerging
infection, and more importantly, its design, testing and development into seed stock for
vaccine production in a few days in the pandemic setting has significant implications for the rapid deployment of
vaccines protecting against
emerging infectious diseases.