Researchers at the Ohio State University, in a new study analyzing the behavior of seasonal H1N1 suggests that pandemic flu may become resistant to Tamiflu, the main drug used against it.
OSU scientists traced the evolutionary history of the seasonal H1N1 influenza virus, which first infected humans during the 1918 pandemic. It is one of three seasonal influenza A viruses that commonly infect humans. The others are H1N2 and H3N2. Within H1N1, two strains of virus circulate in humans: a seasonal form and the pandemic form of influenza known as swine flu, which has affected millions and killed thousands of people since it first emerged in North America last spring.
Gradually, the H1N1 strain of seasonal influenza surviving around the world has developed mutations that have caused it to become resistant to oseltamivir-based agents. Tamiflu is the trade name for oseltamivir phosphate.
Daniel Janies, associate professor of biomedical informatics at Ohio State and primary author of the study, said: "Something happened in 2008, when drug resistance took hold.
"The drug-resistant isolates became the ones that survived all over the world. This is just static now. The seasonal H1N1 influenza virus is fixed at resistant."
Janies and his team have traced the history of the same mutation in the pandemic H1N1 strain of the virus as well, with data from its emergence last spring until last December. And they are beginning to see the same kinds of mutation in this virus - changes to an amino acid that allow the virus to resist the effects of oseltamivir - that they saw in the seasonal H1N1 flu.
Janies said: "It is a pretty good bet that whatever pressure is in the environment, excessive use of Tamiflu or something else, that was driving seasonal influenza to become resistant to Tamiflu is also going to apply to pandemic influenza.
"We can see it happening already.
"This has potential to indicate that we are going to have to think of something else to use to treat pandemic H1N1 influenza."