UGA researchers have used a virus commonly found in dogs as the foundation for a new vaccine against H7N9 influenza, more commonly known as bird flu.
H7N9 is one of several influenza virus strains that circulate in bird populations, and the first human cases were reported in China in March 2013, according to the World Health Organization. The H7N9 virus strain is particularly concerning, however, because most patients rapidly develop severe pneumonia that sometimes requires intensive care and mechanical ventilation.
“The mortality rate for this virus is over 30 percent, so there is an urgent need to develop a good vaccine,” said study co-author Biao He, who holds the Fred C. Davison Distinguished University Chair in Veterinary Medicine in UGA’s College of Veterinary Medicine. “We have developed a vaccine that protected both mice and guinea pigs against a lethal H7N9 challenge, and we think it may be a very strong candidate for human vaccine tests.”
He and his collaborators, in the study detailed in the journal PLOS ONE, used another virus called parainfluenza virus 5, or PIV5, as a kind of delivery vehicle for their H7N9 vaccine. Although harmless in humans, PIV5 is thought to contribute to upper respiratory infections in dogs.
Small segments of H7N9 genes are placed inside PIV5, which is then used to immunize animals. While destroying the harmless PIV5 carrier, the immune system learns to recognize and destroy H7N9 before it can cause severe illness.
“All of the vaccinated mice were protected against the H7N9 virus,” He said. “But our experiments also revealed an unexpected result: The vaccinated animals did not produce a detectable level of antibodies.”
He and his colleagues plan to continue investigating their H7N9 vaccine in other animal models, but he hopes that their most recent discovery may lead other researchers to re-examine vaccines that did not produce a high antibody titer.
“There may be a lot of perfectly good vaccines out there for a variety of diseases that were simply shelved because they did not perform well on the antibody titer test,” He said.