Vaccine Protects Animals Against Avian Flu

H5N1 viruses (seen in gold) in
cell culture; © PHIL

"The results of this animal trial are very promising, not only because our vaccine completely protected animals that otherwise would have died, but also because we found that one form of the vaccine stimulates several lines of immunity against H5N1," said Andrea Gambotto, M.D., assistant professor in the departments of surgery and molecular genetics and biochemistry at the University of Pittsburgh School of Medicine.

Gambotto and his colleagues constructed the vaccine by genetically engineering a common cold virus, called adenovirus, to express either all or parts of an avian influenza protein called hemagglutinin (HA) on its surface. Found on the surface of all influenza viruses, HA allows the virus to attach to the cell that is being infected and is, therefore, critical to the influenza virus' ability to cause illness and death.

Most of the mice immunised with the adenovirus containing either the whole or part of the HA protein showed only mild and short-lived weight loss and survived H5N1 infection. Based on that superior degree of protection Gambotto's group tested its effectiveness in chickens: All of them immunised subcutaneously survived exposure to H5N1, developed strong HA-specific antibody responses and showed no clinical signs of disease.

Gambotto and colleagues suggest that rather than replacing traditional inactivated influenza vaccines, their adenovirus-based vaccine could be a critically important complement. A recombinant vaccine could be an attractive alternative for human immunisation as well, they said. Gambotto and his group is planning a small clinical trial of the vaccine in humans in the very near future.; Source: University of Pittsburgh