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Identification of Cattle Virus Helps Researchers Better Screen BSE

UC Davis researchers sequence genome of new cow virus that causes similar symptoms to BSE

Published on: Aug 15, 2013

Researchers at the University of California Davis have sequenced the genome of a new neurologic virus that causes symptoms in cows similar to bovine spongiform encephalopathy, providing a new way to better understand BSE itself.

Patricia Pesavento, a veterinary pathologist in the UC Davis School of Veterinary Medicine and study author, explains that neurologic diseases in cattle can be difficult to diagnose because there are a number of different causes, and pre-mortem sampling and analyses can be cumbersome and expensive.

While the newly identified virus – called BoAstV0NeuroS – does not pose a threat to human health, its genome is particularly useful for veterinarians, researchers and producers looking for better ways to rule out BSE when treating cattle with neurologic disorders.

UC Davis researchers sequence genome of new cow virus that causes similar symptoms to BSE
UC Davis researchers sequence genome of new cow virus that causes similar symptoms to BSE

"Finding new viruses helps us identify other, more remote viruses because it builds our knowledge of both the depth and breadth of viral family trees," she explained, highlighting the importance of early and rapid recognition of the causes of neurologic disease in cattle.

To identify the new disease, researchers analyzed the brain tissue from a yearling steer with neurologic symptoms of unknown cause. Through the course of the analysis, researchers found that the virus belongs to the astrovirus family, a collection of small viruses known to affect mammals, birds and humans with compromised immune systems.

A vacuolated, dying neuron (black arrow) within the spinal cord of a cow infected with Bovine Astrovirus (UC Davis photo)
A vacuolated, dying neuron (black arrow) within the spinal cord of a cow infected with Bovine Astrovirus (UC Davis photo)

Before the discovery, astroviruses had only been identified in neurologic issues in two other instances. Researchers said BoAstV0NeuroS makes the third virus associated with neurologic disease.

Continued examination of cattle with suspected neurological disease identified three additional cattle with a disorder similar to BoAstV0NeuroS. The virus is most likely to be found in the spinal cord, and creates a patterned abnormality that allows it to be separated from BSE, thus allowing researchers to use BoAstV0NeuroS testing methods to rule out BSE.

"Further research is needed to determine the viral origin and progression, like whether development of neurologic symptoms from this astrovirus requires other factors such as a co-infection by some other microbe or a weakened immune system," Pesavento said.

However, understanding of the new virus and subsequent testing will pave the way for continued surveillance of neurologic cattle diseases and safeguards for the human food chain.

Results of the study appear online in the September issue of the Emerging Infectious Diseases Journal, published by the U.S. Centers for Disease Control and Prevention.