Swine Flu thoughts (H1N1)

My first thought on hearing of the swine flu outbreak was that society continues to go 1970's retro. Last I heard of it was around 1976.

So what is the H1N1 or swine flu? Good question. It's a flu virus that started in pigs, but has mutated enough so that it can now infect humans. Flu viruses have chemical markers on their outer surface. It is these adhesins that allow for the binding of the flu virus to cell surfaces before they infiltrate and infect them. The "H1N1" moniker refers to these markers on the virus surface.

These adhesins give the flu virus specificity for hosts. This is why dog viruses don't infect humans and vice versa. That is, until they do. Viruses can have a high mutation rate. Part of the reason for this is some don't really have a lot of mechanisms to make sure that their DNA is copied correctly. This is where mutations arise. This is especially true of viruses such as the flu virus where their genetic information is carried in RNA instead of DNA. And the flu virus is an RNA virus.

See, viruses have to get inside of intact cells in order to reproduce and manufacture more virus particles. They're stripped down life forms that carry genetic information and not much else. They use the host cell for energy and for expressing their genetic information and manufacturing virus proteins--guided by the virus genetic information. They storm the cell and take over, kind of like an invading army. It's an efficient way of life unless your genetic information is contained as RNA. The host doesn't have the enzymes to copy RNA like that. The virus usually has to carry the information for making it, and frankly RNA replication doesn't have as robust as a proof-reading mechanism as DNA replication does.

And viruses are simple organisms to begin with. They only have a few genes as opposed to thousands for bacteria and multiples of thousand for humans.

For the flu virus this means that the adhesin genes change, which lead to the adhesin proteins change. This ultimately results in different adhesin proteins on the surface of flu viruses which can, if the right combination of mutations occur, change a virus that would normally infect pigs now infect humans. (same with birds to humans). Physiologically and biochemically, it turns out that pigs are quite similar to humans.

For more information on the outbreak, check out the CDC website for swine flu. For more information on the life cycle of the flu virus itself check out this site.