Researchers from the University of Pittsburgh Center for Vaccine Research reverse-engineered an elusive virus linked to chronic kidney disease in cats and described its mode of infection, outlining its potential to infect humans, in a study that was published this week in the Proceedings of the National Academy of Sciences.
According to the findings, measles and other members of the morbillivirus family, including the feline morbillivirus, employ the same mechanism to enter cells and cause infection. FeMV appears to travel from host to host by urine, unlike measles, and in a manner akin to that of the zoonotic Nipah virus carried by bats, which annually produces devastating epidemics in people throughout Southeast Asia.
The work offers the first precise understanding of this poorly understood virus and its possible path from infecting animals to infecting humans.
"Feline morbillivirus stayed under the radar for many years," said senior author Paul Duprex, PhD, director of the Center for Vaccine Research at Pitt's School of Medicine. "By understanding the genetics of a virus that was challenging to grow in the laboratory, we are now able to shine a light on its connection to chronic kidney disease and better understand how we can stop transmission and potential spillover into human populations."
FeMV has first identified in stray cats in Hong Kong ten years ago. Since then, it has been found in domestic cats throughout Asia and Europe. Duprex's research team in Boston was able to sequence FeMV in 2016 and identify it fully. The new work demonstrates in unprecedented detail how the virus enters the kidneys, despite the fact that earlier studies have connected FeMV infections to chronic renal disease in cats--one of the significant causes of death in older animals.
FeMV enters cells similarly to other members of the same virus family by attaching to the CD150 surface protein receptor. People who have received the measles vaccine are shielded from contracting FeMV because related viruses, such as measles, employ CD150 as their main entrance receptor. However, the elimination of measles could provide other morbilliviruses, including FeMV, an evolutionary opening to look for new hosts and infect those who haven't received vaccinations.
"That's why illuminating animal diseases proactively matters," said Duprex. "Preparedness is vital in heading off an epidemic."
Researchers were able to follow the spread of FeMV across cells and organs by developing a genetically altered variant that included a fluorescent probe. They found that cathepsin inhibition can stop the development of FeMV. The fact that the majority of Nipah viruses use cathepsins but not the morbilliviruses suggests that FeMV represents an evolutionary link between the two viral groups.
"It's important to understand the pathogens of animals because those can become the pathogens of people," said Duprex. "Learning about the viruses that infect cats is not only important for reducing the rates of kidney failure in our beloved pets but also helps us understand something new about emerging infectious diseases and how they can spread across different animal species. There are about 85 million cats in the U.S. and over half a billion worldwide. We live with them in close proximity and their health matters."
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