H1N1 - What's in a name?
What is a virus?
Viruses are considered to be non-living. These infectious particles consist of a nucleic acid core (DNA or RNA) surrounded by a protein shell (called a capsid) - sort of the tootsie pop of the microbial world. Viruses do not exhibit a metabolism of their own and cannot reproduce without first infecting a host cell. Common species of viruses include HIV, Influenza, and West Nile.
What does H1N1 mean?
Viruses have a specific host range; in other words, each type of virus typically infects one type of organism. So, feline viruses infect cats; porcine viruses infect pigs; human viruses infect humans; etc. The host range of the virus is controlled by particular proteins, called spikes, that mediate binding of the virus to the host cell.
Flu strains are named according the the H and the N spike proteins. The H is the hemagglutinin protein and the N is the neuraminidase protein. Hemagglutinin is responsible for recognition and entry of the host cell, while the neuraminidase is responsible for the subsequent escape of new viral particles from the infected cell. In the case of the "swine flu", the specific H and N proteins involved are H1 and N1.