Newswise — Infectious disease experts are awaiting an infinitesimal event of momentous importance: the mutation of the novel H1N1 influenza virus. “The Centers for Disease Control and Prevention and the World Health Organization are constantly monitoring the virus as it spreads,” says John Tudor, Ph.D., a microbiologist and professor of biology at Saint Joseph’s University in Philadelphia, “but there is no way to predict where, when or if mutation will occur.”
Scientists do know how the virus can mutate. “The mutation, or antigenic shift, would occur in a cell when it is infected with two different strains of the H1N1 virus,” says Tudor. “When this happens, a reassortment of genetic information may end up in a single virus particle, making a new strain, which may be more or less virulent than the original.”
Tudor notes that these are the kinds of mutations that worry most scientists, with many asking: How would a mutation affect the vaccine?
“Minor changes in the viral genome sequence can also occur, which may affect the efficacy of a vaccine,” says Tudor. “But even if a mutation occurs, it is likely that an H1N1 vaccine would still provide a significant level of protection against related strains. The level of protection would depend on how closely related the mutated strain is to the strain(s) used in producing the vaccine.”
Though known as “swine” flu, Tudor notes this may be a misnomer. “Analysis of the genome indicates it contains genetic fragments from Asian and European pigs as well as birds and humans of unknown source. Since the origin of the genetic elements came from four sources, it’s called a quadruple reassortment virus.”
According to Tudor, “H” and “N” refers to two components of the virus: Hemagglutinin and Neuraminidase, which can occur in 144 possible combinations. Luckily, only three usually infect humans – H1N1, H2N2 and H3N2. “The anti-flu medications Tamiflu and Relenza act by blocking the N component,” he notes.
Tudor warns that the prophylactic use of Tamiflu could contribute to the virus becoming resistant. “Staff at a camp in North Carolina gave campers prophylactic doses, and later, when some became ill, Tamiflu didn’t help. Like any other medication, we need to use it appropriately for it to be effective. The CDC recommends against giving flu drugs to healthy people in order to prevent illness.”
Historically, there have been other instances of seasonal flu designated H1N1. “Studies have concluded both seasonal flu virus and variants like the current H1N1 are probably descended from the 1918 influenza known as Spanish Flu,” Tudor says.
Though the 1918 flu caused millions to perish, Tudor says recent descendants of the virus appear to cause less severe disease. “This is apparently the case for the present pandemic.”
In the meantime, Tudor is keeping his fingers crossed, hoping for the less virulent mutation, or no mutation at all.
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