Influenza A

the most common type of influenza. These strains have a high propensity for antigenic change resulting in mutations, partly because they can infect various animals where dual infections can occur, giving rise to new hybrid strains. The infections occur in epidemics, which may occur every 2-3 years and which vary in size and severity; perhaps the most important of the three types of influenza (A, B, and C).

Per Stedmans :)

and...

Influenza virus

The family of Orthomyxoviridae contains 3 genera: Influenzavirus A, B; Influenzavirus C; and "Thogoto-like viruses." Each type of virus has a stable nucleoprotein group antigen common to all strains of the type, but distinct from that of the other type; the genome is negative sense single-stranded RNA in 6-8 segments; each also has a mosaic of surface antigens (hemagglutinin and neuraminidase) that characterize the strains and that are subject to variations of two kinds: 1) a rather continual drift that occurs independently within the hemagglutinin and neuraminidase antigens; 2) after a period of years, a sudden shift (notably in type A virus of human origin) to a different hemagglutinin or neuraminidase antigen. The sudden major shifts are the basis of subdivisions of type A virus of human origin, which occur following infection of the animal host with 2 different strains at the same time, resulting in a hybrid virus. Strain notations indicate type, geographic origin, year of isolation, and, in the case of type A strains, the characterizing subtypes of hemagglutinin and neuraminidase antigens (e.g., A/Hong Kong/1/68 (H3 N2); B/Hong Kong/5/72).

This is probably a stupid question, but what does the "A" in influenza A stand for?

More specifically when referring to AH5N1 (Avian Flu)

Thanks,

Melanie

It relates to the antigen involved. This one has an AH5N1 antigen.

World Health Organization

http://www.who.int/csr/disease/avian_influenza/guidelines/infectioncontrol1/en/

It's a PDF file you have to actually read..but some of it is pretty interesting.

I appreciate everyone's responses, however the actual homework (extra credit) question is what does the "A" stand for?

Thanks

I thought that A is the type and H5N1 is the subtype??????