Virologists Study H7N9′s Family Tree to Predict Pandemic Threat
By Gemma Tarlach
Discovermagazine.com
The devil is in the details when it comes to predicting the next viral killer.
As a candidate for the next virus most likely to cause a pandemic, influenza virus H7N9 has gotten attention. Earlier this year, the previously unknown avian virus emerged from the poultry markets of eastern China to infect more than 130 people, killing at least 39.
Now researchers report that a DNA sequence H7N9 has appropriated from another virus, among other factors, make it particularly worrisome. To understand how H7N9 might evolve into a pandemic-ready pathogen, the scientists summarized unusual characteristics of the virus, as well as the entire H7 family, in a review published today in mBio, the online, open-access journal of the American Society for Microbiology.
Stolen genes
Chief among concerns raised in the review is that H7N9 contains an internal gene cassette — essentially a piece of DNA — from the avian virus H9N2. One virus having a piece of DNA from another is not unusual: wild birds, the natural hosts of avian viruses, often are infected with multiple strains, which frequently results in gene-shuffling amongst them.
H7N9′s filching from H9N2 is of concern because the H9 virus family has caused widespread human infection in the past and can move rapidly between avian and mammalian hosts. If H7N9 were to adapt to have these characteristics it would significantly increase the risk of pandemic.
H7N9, like some other H7 viruses, also shows a tendency to infect human conjunctival cells lining the white of the eye and inside of the eyelids. This infection route results in early symptoms like conjunctivitis more frequently than the respiratory symptoms typically associated with influenza, which could cause health practitioners to miss the earliest signs of an outbreak. Conjunctivitis sufferers also often wipe or rub their eyes, which could heighten risk of person-to-person transmission.
The Rest…HERE
