(HealthDay News) – Five mutations in a pandemic avian influenza virus can allow airborne transmission of the virus between ferrets.

Sander Herfst, PhD, from the Erasmus Medical Center in Rotterdam, Netherlands, and colleagues used site-directed mutagenesis to genetically modify the human pathogenic avian influenza A/H5N1 virus, and subsequently serial passaged the virus in ferrets. The authors sought to determine whether A/H5N1 virus could acquire mutations that would increase the risk of mammalian transmission.

The researchers found that the modified virus evolved additional novel mutations in ferrets. The new viruses became airborne transmissible, although none of the recipients died after airborne infection with the modified virus. The airborne-transmitted viruses had five consistent mutations, of which four were in the host receptor-binding protein hemagglutinin and one was in the polymerase complex protein basic polymerase 2. The viruses were susceptible to treatment with oseltamivir and reacted with antisera raised against H5 influenza.

“Thus, avian A/H5N1 influenza viruses can acquire the capacity for airborne transmission between mammals without recombination in an intermediate host and therefore constitute a risk for human pandemic influenza,” Herfst and colleagues conclude.

Several authors disclosed financial ties to the biotechnology and pharmaceutical industries.

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