>>Why do you think the sequences were made in a laboratory?<<
I said the sequences came from a lab (not made in a lab). Here is a little more detail. Labs that study viruses isolate them and store samples. When the sample is stored (frozen), the genetic information is in suspended animation. When the virus gets thawed and begins to grow, for the virus its like "The Time Machine". I comes back to life at a later date.
WS/33 was the first human virus isolated. It was from a physician (Christopher Andrewes) in England in 1933. The first author on the 1933 Lancet paper was Wilson Smith (hence the WS name of the virus). In 1940 there was interest in studying the neurotropic effects seen in the 1918 pandemic, so WS/33 was used to infect mice and WSN/33 was isolated from mouse brain (the N is for neurotropic).
WSN/33 became popular because it could grow in tissue culture. In this case it was MDCK cells, a popular line established by Madin and Darby from Canine Kidney cells, hence the name MDCK. These cells are used to isolate viruses such as the SARS CoV. WSN/33 can grow in tissue culture because its N is missing a glycosylation site and this allows it to sequester plasminiogen (a precursor to a protease found in plasma), which then cleaves HA to let the flu virus enter a cell. Thus, WSN/33 is particularly virulent because it hijacks a common protease to help it infect cells (these virus are much smarter than most realize).
WSN/33 has a number of unusual genetic markers including a 16 aa deletion in NA, a 1 aa deletion in HA, and a mutation in M2 that makes it resitant to Amantadine. These various markers serve as a genetic finger print. In addition, the virus changes over time to survive and these changes also can be used to identify viruses.
The viruses isolated in 2004 pigs have different combinations of human flu genes (also identified by the sequence) and each of the human flu genes is over 99% homologous (matches) to WSN/33 and they have the characteristic finger prints identified above.
recombinomics.com
Since WSN/33 has spent much of the past 70 years in suspended animation in a freezer in some lab, gentically it looks like it did in 1933. As it grows in pigs it begins to chnage again almost all of the WSN/33 genes in 2004 are slightly different than WSN/33 and each other, indicating the infectious are fairly recent and they came from WSN/33.
Hence the virus is from a lab (not made in a lab), and since the virus is from 1933, the differences between 1933 and 2004 viruses will be picked up by infected person's immune system and WSN/33 will look very foreign (just like an avian flu gene would look very foreign) and an agressive foregn flu virus can be a very dangerous thing. |
