http://www.digitaljournal.com/science/find-out-why-some-chickens-are-resistant-to-bird-flu/article/470443

It’s all in the genes: Why some chickens are bird flu resistant

Posted Jul 19, 2016 by Tim Sandle
Combating the risks associated with bird flu is of global importance. While some research focuses on treatment, and other parts on addressing transmission, another strand looks at patterns of susceptibility.
Dutch authorities in 2014 culled 150 000 chickens at the farm in Hekendorp  after discovering a stra...
Dutch authorities in 2014 culled 150,000 chickens at the farm in Hekendorp, after discovering a strain of bird flu.
Fred Tanneau, AFP/File
One area of interest to virologists is in understanding how the genes of some chickens confer resistance to a serious strain of bird flu. This is a key research subject at the School of Life Sciences at the University of Lincoln, U.K. (as notified via the university's Twitter account — Uni. of Lincoln UK @unilincoln.)
Bird flu, or avian flu, is an infectious type of influenza that spreads among birds. In rare cases, it can affect humans. Two particular strains have caused serious concern in recent years: H5N1 (since 1997) and H7N9 (since 2013).
Here a research group led by Dr. Colin Butter has examined different chicken susceptibilities to avian influenza. The reason is, he explained in his research note: “Until now we knew relatively little about how a bird's genetics can affect its reaction to flu virus but this new research, which for the first time shows that some poultry lines are genetically resistant to avian flu, represents a significant step forwards.”
Dr. Butter has observed that some chickens are capable of carrying (and therefore transmitting) avian flu but they themselves are genetically resistant to the disease. The viral infection is associated with the respiratory tract and remains only for a limited period of time.
In contrast, chickens that are susceptible to avian influenza remain infectious for as long as they are alive. Moreover, such birds can transmit the virus via feces as well showing effects of the virus in their respiratory system.
Given that the primary means of the flu virus spreading is through feces, the genetically resistant chickens are not classed as infectious. It is though there is a mechanism at play that prevents the virus from being spread when inside the body of the resistant bird.
Researchers hope that by understanding more about the virus-host relationship, measures can be taken to increase the level of resistance; to set up breeding programs; and to use resistant birds to prevent infectious from spreading within and outside of chicken communities. This will require a greater understanding of the mechanisms of resistance.
The research has been published in the journal Scientific Reports. The research is titled “Host genetics determine susceptibility to avian influenza infection and transmission dynamics.”