Farmed carnivores may become 'disease reservoirs' posing human health
risk

Date:
August 24, 2021
Source:
University of Cambridge
Summary:
Carnivorous animals lack key genes needed to detect and respond to
infection by pathogens, a study has found. Farming large numbers
of carnivores, like mink, could allow the formation of undetected
'disease reservoirs', in which a pathogen could spread to many
animals and mutate to become a risk to human health.



FULL STORY ========================================================================== Carnivorous animals lack key genes needed to detect and respond to
infection by pathogens, a study has found. Farming large numbers of
carnivores, like mink, could allow the formation of undetected 'disease reservoirs', in which a pathogen could spread to many animals and mutate
to become a risk to human health.


========================================================================== Research led by the University of Cambridge has discovered that carnivores
have a defective immune system, which makes them likely to be asymptomatic carriers of disease-causing pathogens.

Three key genes in carnivores that are critical for gut health were found
to have lost their function. If these genes were working, they would
produce protein complexes called inflammasomes to activate inflammatory responses and fight off pathogens. The study is published today in the
journal Cell Reports.

The researchers say that the carnivorous diet, which is high in protein,
is thought to have antimicrobial properties that could compensate for
the loss of these immune pathways in carnivores -- any gut infection is expelled by the production of diarrhea. But the immune deficiency means
that other pathogens can reside undetected elsewhere in these animals.

"We've found that a whole cohort of inflammatory genes is missing in
carnivores -- we didn't expect this at all," said Professor Clare Bryant
in the University of Cambridge's Department of Veterinary Medicine,
senior author of the paper.

She added: "We think that the lack of these functioning genes contributes
to the ability of pathogens to hide undetected in carnivores, to
potentially mutate and be transmitted becoming a human health risk."
Zoonotic pathogens are those that live in animal hosts before jumping
to infect humans. The COVID-19 pandemic, thought to originate in a wild
animal, has shown the enormous damage that can be wrought by a novel
human disease. Carnivores include mink, dogs, and cats, and are the
biggest carriers of zoonotic pathogens.

Three genes appear to be in the process of being lost entirely in
carnivores: the DNA is still present but it is not expressed, meaning
they have become 'pseudogenes' and are not functioning. A third gene
important for gut health has developed a unique mutation, causing two
proteins called caspases to be fused together to change their function
so they can no longer respond to some pathogens in the animal's body.

"When you have a large population of farmed carnivorous animals, like
mink, they can harbour a pathogen -- like SARS-CoV-2 and others --
and it can mutate because the immune system of the mink isn't being
activated. This could potentially spread into humans," said Bryant.

The researchers say that the results are not a reason to be concerned
about COVID-19 being spread by dogs and cats. There is no evidence that
these domestic pets carry or transmit COVID-19. It is when large numbers
of carnivores are kept together in close proximity that a large reservoir
of the pathogen can build up amongst them, and potentially mutate.

========================================================================== Story Source: Materials provided by University_of_Cambridge. The original
text of this story is licensed under a Creative_Commons_License. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Zsofi Digby, Panagiotis Tourlomousis, James Rooney, Joseph P. Boyle,
Betsaida Bibo-Verdugo, Robert J. Pickering, Steven J. Webster,
Thomas P.

Monie, Lee J. Hopkins, Nobuhiko Kayagaki, Guy S. Salvesen, Soren
Warming, Lucy Weinert, Clare E. Bryant. Evolutionary loss of
inflammasomes in the Carnivora and implications for the carriage
of zoonotic infections. Cell Reports, 2021; 36 (8): 109614 DOI:
10.1016/j.celrep.2021.109614 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210824121049.htm

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