Are there many different types of H5 avian influenza “bird flu” viruses?
There are many types of H5, which may have been in circulation for thousands of years. The first thing to know is that it’s a huge leap for a bird virus to become a human virus that spreads efficiently in people Influenza A viruses are divided into categories or subtypes based on their two surface proteins they carry – hemaglutinin and neuraminidase. To date, scientists have found 16 hemagluttinins and nine neuraminidases, the H and the N in a flu virus’s name. In theory there may be 144 different combinations.’ But some Hs and Ns have never been found together, leading experts to think that some combinations cannot be formed. Most of the known combinations have shown no talent at infecting people. Even within a subtype, there is a lot of variation among viruses. There is no cookie cutter that punches out identical H5N1s. So when H5N1 viruses have been found scientists needed to perform genetic analysis on them to see how closely matched they are to the Asian viruses. Q : How does a “b
