Focus on the Flu

Public health officials who warn of a looming flu pandemic cite as cause for worry recent Asian cases in which influenza viruses normally restricted to aquatic birds were transmitted to humans. Fortunately, in each case, the virus stopped short of spreading from person to person. But the growing fear is that, if a bird influenza virus became transmissible among people, the new strain would be unrecognized by the human immune system, leading to widespread infection, illness and death. Three such 20th-century pandemics occurred in 1918, 1957, and 1968.

Kanta Subbarao, M.D., senior investigator in the Respiratory Viruses Section of NIAID's Laboratory of Infectious Diseases, headed by Brian Murphy, M.D. and Robert Purcell, M.D., is working to prevent the worst case scenario from occurring. She and others in the lab are creating a vaccine for each of the 15 hemagglutinin proteins found in bird strains of influenza A that currently are not transmissible to humans. In this way, should a strain containing any one of these proteins make the jump to people, a vaccine could be prepared rapidly. The live, attenuated vaccines would be given as a nasal spray.

Heading the list of vaccines to be developed are those for the proteins H2, H5, H7, and H9, which is in keeping with priorities set by the World Health Organization. H2, though currently transmissible among humans, has not circulated since 1968; therefore, anyone born after that year has never been exposed to it.

Once the pandemic vaccines have been developed, they will be tested—first in animals and later in humans—for safety and the ability to spur an immune response.

• For more information on Dr. Subbarao's research, please visit her NIAID laboratory Web page.