Friday, July 28, 2017

Arch. Of Virology: Novel Reassortant H5N6 Isolated From Cats - Eastern China



Until cats (both large and small) began dying in Asia from avian H5N1 back in 2004, it was generally believed that cats were relatively immune to influenza A infection. Gradually that perception has changed (see Catch As Cats Can) - particularly with regard to novel flu viruses (see Companion Animals And Novel H1N1). 
Last winter we saw a large, unprecedented outbreak of avian H7N2 among hundreds of cats in New York City animal shelters (see NYC Health Dept. Statement On Avian H7N2 In Cats) which eventually led to one human infection (link).
At almost the same time, South Korea announced the discovery of at least 3 cats infected with the H5N6 virus in Gyeonggi Province (see Korean CDC Statement On H5N6 In Cats).  MAFRA's Quarantine division immediately announced plans to test stray cats in and around multiple areas that have been hit by avian influenza. 
Increasingly cats (and dogs) are viewed as potential intermediate hosts for novel influenza viruses.
These companion animals - who often interface with wildlife - are in a unique position to serve as a conduit for zoonotic viruses to humans, even in urban settings.

Which brings us to the following study, whose details are sadly tucked behind a paywall. Luckily the abstract still provides us with a fair amount of information.
Genetic characterization of novel reassortant H5N6-subtype influenza viruses isolated from cats in eastern China

Xueliang Cao, Fan Yang,Haibo Wu, Lihua Xu
Brief Report  First Online: 21 July 2017

Cats are susceptible to influenza A viruses and therefore may act as transmission vectors within households, posing a potential public health concern. Two novel reassortant H5N6 influenza viruses were isolated from cats in Zhejiang Province, Eastern China, in 2016.
Both viruses were characterized by whole-genome sequencing with subsequent phylogenetic analysis and genetic comparison. Phylogenetic analysis showed that these viruses received their genes from H5N6, H9N2, and H7N9 influenza viruses isolated from China. These H5N6 viruses were able to replicate in mice without prior adaptation. Our results show that continued circulation of these viruses could endanger humans.
We aren't provided with any details on this novel reassortant, other than its parental viruses (H5N6, H9N2, and H7N9).  It does, however, reaffirm that the promiscuous H5N6 virus continues to reassort with other viruses in China.

The discovery that these avian H5N6 viruses were able to replicate without adaptation in mice suggests that while these cats might have been infected through contact with infected birds, it could just as easily have come from contact with small mammals or rodents.

Over the years we've looked at the potential role of peridomestic animals (cats, dogs, rodents, small mammals, etc.) in spreading avian flu viruses, and affecting its evolution.

More evidence that things we used to think were rare with novel influenza viruses, may be more commonplace than we know.