| Animal Health
It’s all in the genes: New research reveals why
some chickens are resistant to bird flu
The genes of some chickens make them almost completely resistant to a serious strain of bird flu, new research has
revealed.
he findings, which are
published in the journal
Scientific Reports, show that
genetics play a key part in
whether the birds are
susceptible or resistant to the
potentially deadly virus. Until now, scientists
around the world have paid little attention to the
role the genetics of birds play in the
transmission of flu, focusing instead on how the
virus itself evolves and infects.
Led by Dr Colin Butter from the School of
Life Sciences at the University of Lincoln, UK,
this new research, which was carried out at The
Pirbright Institute, could prove valuable in
developing our understanding of the
mechanisms of influenza transmission within
and between birds. Dr Butter is one of the UK’s
leading authorities on avian flu with expertise in
animal science, virology and immunology.
Influenza virus is the cause of influenza, or
‘flu’ – the contagious respiratory viral disease
common in many birds and mammals. The
viruses circulating in wild birds and
domesticated poultry are of particular interest
to scientists because they may mutate into
forms that are capable of infecting humans, and
represent an emerging threat to human health
as potential sources of the next flu pandemic.
This danger has led the World Health
Organisation to highlight effective control
measures, as well as an in-depth assessment
of factors surrounding the infection of host
animals, as part of their research priorities. Dr
Butter’s study takes an important step towards
meeting these needs.
Dr Butter, Reader in Bioveterinary Science at
the University of Lincoln, said: “It is important
T
for us to understand how different genetic lines
of bird react to influenza viruses, so that we can
begin to understand the spread of the disease.
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.
“Our results are valuable in emphasising the
important role a ‘host’ plays in the spread of
avian flu, and also in highlighting a number
factors relating to the chain of infection and
control mechanisms which are affected by the
route of infection.”
The research team, based at The Pirbright
Institute (an international research centre
working to improve the health of farm animals
worldwide), also included specialists from the
University of Oxford and The Francis Crick
Institute in London and was funded by the
Biotechnology and Biological Sciences
Research Council (BBSRC). The researchers
examined two different lines of chickens to
determine whether genetics played a part in the
susceptibility or resistance to infection.
They found that birds that carried the virus
but were genetically resistant to the disease
only shed the virus through their respiratory
tract and for a limited period of time, whereas
birds which were susceptible to the disease
also shed virus in faeces and over a longer
time. The researchers discovered that this was
the only relevant means of spreading the virus
and that resistant birds were therefore
completely unable to initiate or sustain a chain
of infection. Further results in the study suggest
that this could be due to a genetic restriction
within the animal which stops the virus
spreading when inside the body.
Professor Venugopal Nair, the Head of the
Avian Viral Diseases programme at The
Pirbright Institute, said: “The findings of this
study emphasise the importance of examining
the intricate nature of the virus-host interactions
and the potential role of the host genetic factors
influencing the transmission dynamics and
outcomes of important diseases such as avian
flu.”
Influenza virus is the cause of influenza, or
‘flu’ – the contagious respiratory viral
disease common in many birds and
mammals
These findings now lead the way for further
investigation and work is being planned to
discover and examine the precise biological
mechanisms behind genetic resistance. This
could have major implications for poultry
breeding, as well as human flu treatments, in
the future.
Dr Butter added: “The prospect of breeding
birds with natural immunity to influenza virus
would certainly widen the scope of existing
control measures and perhaps limit the risk to
the human population of the emergence of
pandemic viruses. Furthermore, as human
genetic determinants for catching flu are
comparatively unknown, research such as ours
which is developing a better understanding of
the genes and mechanisms involved could als