What are the meanings of A - H - N - 1 - 09 in the A H1N1 09 flu name?

Answer 1

Background information about names of flu virus strains:

For background, H1N1 is the name used to identify several subtypes of flu viruses. A few of the influenza viruses that are in the group of Type A Influenza viruses are labeled that way or in similar ways.

These influenza A virus strains are categorized according to two proteins found on the surface of the virus: hemagglutinin (H) and neuraminidase (N). All influenza A viruses contain hemagglutinin and neuraminidase, but the structure of these proteins differ from strain to strain due to rapid genetic mutation in the viral genome.

Influenza A virus strains are assigned an H number and an N number based on which forms of these two proteins the strain contains. There are 16 H and 9 N subtypes known in birds, but only H 1, 2 and 3, and N 1 and 2 are commonly found in humans. There are also Influenza type B viruses.

Example Swine Flu:

An example is the new "Swine Flu" virus circulating in 2009, the "Influenza A, Novel H1N1/09" Virus. It evolved from a virus that started as a flu that only pigs could get, which is called H1N1, too. But that mutated to a strain that could also infrequently infect humans who were in very close contact with pigs, such as farmers who raised them. The new "Novel H1N1" virus was a further mutation that combined human, bird, and swine flu genes.

The Centers for Disease Control and Prevention and World Health Organization call the pandemic 2009 "Swine Flu": Influenza A, Novel H1N1 Virus. You may also see it written as the "Novel H1N1 Influenza virus", or "Novel Influenza A, H1N1 virus", or "H1N1, formerly Swine Flu".

It has different names in other countries as well, for example: it is called Schweinegrippe in Germany, la Grippe A in France, Mexican Flu in the Netherlands, SOIV (Swine Origin Influenza Virus) in Canada, and la epidemia in Mexico.

The reason they call it "Novel" is that it is new. It is a strain not seen before. There are other strains of H1N1 influenza, but this one has different and new genetic material than the previously seen strains of Type A flu.

What A-H1N1 means:

"A" stands for the influenza sub-type or strain.

These Type A viruses have a protein coating that surrounds them, called a capsid. The surface proteins making up the capsid in these virus strains are Hemagglutinin and Neuraminidase. These surface proteins are the parts of a virus that can be changed when viruses mutate into new forms. This is how they change to be able to attack the cells of new hosts or in new ways in the same hosts. They are no longer recognized as viruses that the immunological system of the host has fought before, and that allows them to mutate to forms that can evade the body's defenses again at first.

In the naming convention of viruses, the protein classifications become part of the name as in H1N1; H for the Hemagglutininand N for the Neuraminidase. Hemagglutinin binds the virus to the cell it is infecting. Neuraminidase is an enzyme that lets the virus be released from the host carrier cell.

There are different subtypes of viruses using the H and N nomenclature, for example the H5N1 subtype is the Avian (Bird) Flu.