When a Florida virologist’s cat brought home a dead shrew, no one expected it to lead to the discovery of a previously unknown virus. But that’s exactly what happened.
The shrew carried a new strain of orthoreovirus—a virus family known to infect mammals, including humans. While its effects on people are still uncertain, some orthoreoviruses have been linked to serious illnesses.
Feline Assistant Strikes Again
Pepper, the house cat who gained attention last year for helping scientists identify the first jeilongvirus ever reported in the United States, has once again played a surprising role in virus discovery. This time, his latest hunting trophy led researchers to a previously unknown strain of orthoreovirus.
Dr. John Lednicky, a virologist at the University of Florida College of Public Health and Health Professions and Pepper’s owner, collected the cat’s find—a dead Everglades short-tailed shrew—and brought it to his lab for analysis. The examination was part of his ongoing research into the transmission of mule deerpox virus.
Human Health Implications of Orthoreovirus
Lab tests revealed that the shrew carried a novel strain of orthoreovirus, a type of virus that can infect various mammals, including humans, bats, and white-tailed deer. Although the full extent of its impact on humans remains unclear, orthoreoviruses have occasionally been linked to serious conditions such as encephalitis, meningitis, and gastrointestinal illness in children.
“The bottom line is we need to pay attention to orthoreoviruses, and know how to rapidly detect them,” said Lednicky, a research professor in the PHHP Department of Environmental and Global Health and a member of UF’s Emerging Pathogens Institute.
The UF team published the complete genomic coding sequences for the virus they named “Gainesville shrew mammalian orthoreovirus type 3 strain UF-1” in the journal Microbiology Resource Announcements.
From Orphan Viruses to Emerging Threats
“There are many different mammalian orthoreoviruses, and not enough is known about this recently identified virus to be concerned,” said the paper’s lead author, Emily DeRuyter, a UF Ph.D. candidate in One Health. “Mammalian orthoreoviruses were originally considered to be ‘orphan’ viruses, present in mammals, including humans, but not associated with diseases. More recently, they have been implicated in respiratory, central nervous system, and gastrointestinal diseases.”
The Lednicky lab’s jeilongvirus and orthoreovirus discoveries come on the heels of the team publishing their discovery of two other novel viruses found in farmed white-tailed deer. Given the propensity of viruses to constantly evolve, paired with the team’s sophisticated lab techniques, finding new viruses isn’t entirely surprising, Lednicky said.
How New Viruses Are Born
“I’m not the first one to say this, but essentially, if you look, you’ll find, and that’s why we keep finding all these new viruses,” Lednicky said.
Like influenza virus, two different types of orthoreovirus can infect a host cell, causing the viruses’ genes to mix and match, in essence, creating a brand new virus, Lednicky said.
Global Echoes of a Deer Virus
In 2019, Lednicky and colleagues isolated the first orthoreovirus found in a deer. That strain’s genes were nearly identical to an orthoreovirus found in farmed mink in China and a deathly ill lion in Japan. How in the world, the scientific community wondered, could the same hybrid virus appear in a farmed deer in Florida and two species of carnivores across the globe? Some experts speculated that components of the animals’ feed could have come from the same manufacturer.
With so many unanswered questions about orthoreoviruses and their modes of transmission, prevalence in human and animal hosts, and just how sick they could make us, more research is needed, DeRuyter and Lednicky said.
Next steps would include serology and immunology studies to understand the threat Gainesville shrew mammalian orthoreovirus type 3 strain UF-1 may hold for humans, wildlife, and pets.
Pepper the Science Cat, Still on Duty
For readers concerned about Pepper’s health, rest assured. He has shown no signs of illness from his outdoor adventures and will likely continue to contribute to scientific discovery through specimen collection.
“This was an opportunistic study,” Lednicky said. “If you come across a dead animal, why not test it instead of just burying it? There is a lot of information that can be gained.”
Reference: “Coding complete sequences of the 10 genomic segments of a mammalian orthoreovirus type 3 isolated from a Blarina peninsulae shrew” by Emily DeRuyter, Robert A. Williams, Kuttichantran Subramaniam and John A. Lednicky, 10 June 2025, Microbiology Resource Announcements.
DOI: 10.1128/mra.00219-25
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