Word: virus
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...says the nightmare scenario would involve the pandemic appearance of the highly pathogenic H5N1 avian influenza. With a mortality rate of more than 60%, the virus is so dangerous to humans that his team can work with it only in biosecurity Level 4 laboratories, the highest level of biological containment available. So far, H5N1 is passed to humans only from birds and is not transmissible between humans. But if it were to swap genes with another influenza virus, possibly H1N1 (through, for example, a patient who contracts the two illnesses simultaneously), a new, more lethal pandemic strain could emerge with...
...hardiness as a human scourge is the result, paradoxically, of the instability of its genetic structure. One flu virus can easily swap genetic information with another or mutate as it reproduces. The World Influenza Centre is one of five WHO centers (there are others in Atlanta, Tokyo and Melbourne, and there's a lab in Memphis specializing in animal influenza) that form the hub of a global influenza-surveillance network. The center receives samples taken from ill patients in more than 100 countries. By examining the genetic makeup of the viruses in these samples, scientists can make educated guesses about...
...reports of a more severe infection with higher mortality rates, we can map the changes that made the virus more severe and monitor its spread. That could help health officials formulate policies," says Hay. "But we are always playing catch-up with flu. It's impossible to stay ahead of this virus...
According to WHO figures, the H1N1 virus has so far proved to be mild, causing only 1,200 deaths among 160,000 confirmed cases. Hay says his team is watching for several changes in the virus' genome that could make the pandemic more severe. The first involves the H1N1 vaccine that is currently in production. The batch is based on a recipe that Hay's team helped put together in April. As it takes six months to produce a vaccine, virologists must be on the lookout for "antigenic drift" - changes in the virus that would let it escape the immune...
...team is also on the lookout for changes in the virus that might make it resistant to the antiviral drug Tamiflu, which has been shown to reduce the severity of the disease caused by many flu viruses. Tamiflu works by inhibiting the neuraminidase enzyme (that's the N in H1N1) and preventing it from doing its job of helping the virus replicate once inside a human cell. But certain amino-acid changes in the neuraminidase can render Tamiflu ineffective. This usually happens over time following extensive prescribing of the drug, but it can also occur spontaneously. In the winter...