Laboratory Origins of WSN/33 in Korean Swine
Recombinomics Commentary
February 22, 2005
>> Or the South Korean lab is working on a flu vaccine, using the WSN/33 human sequence from 1933 as a basic template and deliberately scrambling it with various animal flus. In such a scenario, the scientists accidentally created these disturbing influenza strains in the lab in their vaccine production effort. I cannot accept the vaccine idea: why in the world would anybody be making a vaccine against a type of human flu that hasn't circulated on earth for more than 70 years? <<
Since the human WSN/33 sequences at GenBank do not appear to be contaminants, their route from a lab to swine on a farm is of great interest. The two most likely possibilities are an accidental release, or an act of bioterrorism. The sequences themselves provide many clues, but none are conclusive.
The human genes are greater than 99% homologous to WSN/33, but there are a few polymorphisms that are in all swine sequences that are absent in WSN/33. These changes could have been generated sometime in the lab, but the polymorphisms seem to be modern and look as though they were picked up from the infected pigs. None of the isolates are 100% human. All have at least one avian gene and there seem to be several avian sources involved. However, all of the sequences are closest to other Korean isolates, although they are most closely related to the 2004 isolates. These data suggest the infections were recent and involve avian sources in or around South Korea.
The selection of WSN/33 as a human virus for mixing experiment seems wrong for a civilian lab. Mixing experiments with contemporary human viruses would yield the same answers and would be safer. WSN/33 is quite lethal in mice, and is very different than contemporary human viruses, so it could be quite lethal in humans also. If the sequences came from a human virus used in a civilian lab and they were part of a mixing experiment, the WSN/33 virus may have been used in error. Another popular human lab strain is PR8, which is used as the backbone for human vaccines. Thus one scenario would involve two lab errors, one using WSN/33 instead of PR8 for vaccine development, and the other allowing the virus to escape. A variation on this scenario would just involve the escape of WSN/33, which subsequently reassorted and recombined with avian sequences to create the six isolated swine viruses.
A more sinister explanation would involve bioterrorism. The bioterror act could simply involve infecting swine with WSN/33. This could have been followed by dual infections by Korean avian viruses which led to the reassortants and recombinants.
At this point all of the possibilities are speculative and open because there has been no investigation into the origins of the sequneces. The existence of the human WSN/33 sequences in swine still remains unclear 4 months after the sequences were deposited at GenBank, and long after a putative terrorist attack.
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