Studies Reveal How Influenza Virus Antigenic Variation Develops and Spreads

During the past decade, influenza strains causing winter epidemics worldwide have originated in the Asian tropics.

The hemagglutinin (HA) protein on the surface of influenza virus is the primary target of antibodies against the virus. The high mutation rate of the HA gene requires that vaccines be reformulated often, and the vaccine makers do not always get it right. For example, for the 2007–2008 season, the available vaccine was less well matched than usual to circulating strains. Two new studies help explain where new flu viruses develop and how they spread.

One international team studied the HA protein in about 13,000 human H3N2 viruses that had been isolated around the world from 2002 to 2007. Their analysis indicates that flu viruses circulate year-round in tropical areas of South and Southeast Asia, constantly creating recurring epidemics with dif…

Reviewing Author

Anthony L. Komaroff, MD

Disclosures

Consultant/Advisory BoardSerImmune Inc.; DxTerity

Grant / Research SupportNIH (1U54NS105542-01)

Editorial BoardsHarvard Health Letter; UpToDate

Anthony L. Komaroff, MD

Disclosures

Consultant/Advisory BoardSerImmune Inc.; DxTerity

Grant / Research SupportNIH (1U54NS105542-01)

Editorial BoardsHarvard Health Letter; UpToDate