According to a report from the Centers for Disease Control and Prevention circulated in the April 14th edition of ProMED Mail, the second of two patients, who contracted H5N1 avian influenza, yielded a virus with two genetic mutations. The changes occurred in the PB2 gene and are associated with replication in mammalian cells. The virus did not, however, demonstrate mutations that would allow person-to-person transmission.
Dr. Richard Webby - St. Judes Childrens' Hospita |
Dr. Richard J. Webby, of St. Jude Children’s Research Hospital and an acknowledged expert on influenza viruses, noted, “There are three major categories of changes we think H5 has to undergo to switch from being a bird virus to being a human virus.” He added, “The sequences from the person in Chile have one of those classes of changes and we also note that of these three sets, this is the easiest one for the virus to make.”
PB2 mutations are common in mammals infected with H5N1 avian influenza virus. Mammalian hosts include mink, foxes, skunks, bears, seals, sea lions, domestic dogs and cats and possibly other wild mammals that have yet to be sampled.