Recent developments in the analysis of the H1N1 swine influenza virus have shown that the lethal viral strain does not combine genes from humans, birds and pigs, as first thought, but that it’s rather made up of a combination of two swine flu strains, which, brought together, are deadly to us. Scientists studying the strains have told Wired that the find may help researchers get a better understanding of how the virus acts, as well as of what methods could be employed to limit and eventually stop its spread.
“This is what we call a reassortment between two currently circulating pig flu viruses. Why it’s emerged in humans is anyone’s guess. It hasn’t been seen before in pigs, as far as I know,” University of Edinburgh Viral Geneticist Andrew Rambaut, who is involved in the H1N1 investigation efforts, explained. He worked on analyzing viral samples collected from two children in California, which were diagnosed as carriers of the swine flu strain.
The US Centers for Disease Control and Prevention (CDC) harvested the viral samples, and then made the genome sequence available to a number of research teams around the world, under what was known as an international database of flu genomes. Though Wired could not obtain an immediate response from the American authorities, documents released by the agency to scientists seem to confirm the suspicions that the lethal strain is actually made up entirely of pig genes, without any other additions.
The experts said that the two strains involved in the new pathogen were the North American and the European pig flu. The former was first described in the 1930s, while the other was thoroughly analyzed and described in 1979. How they combined is still a mystery, but geneticists argued that the “active ingredient” in the mix, which allowed it to become contagious to humans, was the neuraminidase enzyme, which coded the N1 designation in H1N1.
“The new neuraminidase gene that came in from Eurasian swine is one we’ve never before seen circulating in humans. That’s one of the reasons it’s spreading rapidly. Very few people will have any immunity to this particular combination, which is what gives the concern that this will be a pandemic rather than just a normal seasonal flu outbreak. It remains to be seen how much and to what extent there is existing immunity,” Rambaut added.
“Influenza virus mutates remarkably rapidly, so there is no doubt that the virus will mutate and evolve in humans. Quite what this evolution will result in is difficult to tell,” University of Pennsylvania virus evolution specialist Eddie Holmes concluded.