Sunday, October 27, 2013

Study: Uncommon #H5N1 mutations may transmit in mammals


A study assessing H5N1 avian flu mutations as the virus spreads in ferrets found that mutations that were present in as few as 5.9% of the viruses infecting one ferret could be transmitted to another, according to data published this week in Nature Communications.
US and Japanese researchers, including Yoshihiro Kawaoka, DVM, PhD, of the University of Wisconsin, used data from transmission studies already conducted by Kawaoka in 2011 on engineered H5N1 strains. Publication of that controversial work was originally halted but later allowed by US biosecurity experts.
The team used deep sequencing to identify genetic mutations that happened as the virus replicated in and transmitted between ferrets. They found that during transmission natural selection acts strongly on hemagglutinin (HA), the protein the virus uses to attach to host cells.
They found that within-host genetic diversity in HA increases during replication but is dramatically reduced upon transmission via respiratory droplets—to only one or two distinct HA segments, a small portion of the viral genome.
However, the discovery that mutations present in only 5.9% of the viruses infecting one ferret could be transmitted to another suggests that even rare mutations could be transmitted if they have an evolutionary advantage, according to a Science Daily story on the study.
"Fully avian viruses may act differently in nature," said lead author Thomas Friedrich, PhD, from the University of Wisconsin. "But the data suggest to us that it wouldn't take many viruses from a chicken to infect a person, if the right mutations were there—even if they were a tiny minority of the overall virus population."
Oct 23 Nature Comm abstract
Oct 23 Science Daily story

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