Black cat brings never-before-seen U.S. virus threat home to Florida scientist

GAINESVILLE, Fla. — On Halloween, tales of black cats often spark thoughts of superstition and mystery. In Gainesville, Florida, however, one ebony-furred feline named Pepper has earned its place in scientific history by leading researchers to an unsettling discovery: the first jeilongvirus ever identified in the United States.

The virus, found in a mouse caught by the cat, demonstrates an eerie ability to infect cells from multiple species, including humans – a finding that has scientists at the University of Florida paying very close attention.

The chance discovery occurred when Pepper brought the mouse home and dropped it right at the feet of its owner, Dr. John Lednicky, a virologist at the University of Florida. Naturally, Lednicky decided to examine the cotton mouse for potential pathogens. While initially searching for traces of mule deerpox virus, the study published in Pathogens instead uncovered something far more significant: a novel virus they named Gainesville rodent jeilong virus 1 (GRJV1).

GRJV1 belongs to the paramyxovirus family, which includes well-known human pathogens like measles and mumps, as well as the deadly Nipah virus. What makes this discovery particularly noteworthy is the virus’s remarkable versatility in infecting different types of cells. In laboratory testing, GRJV1 successfully infected and replicated in cells from various species, showing particular affinity for human, primate, and rodent cells. This broad host range suggests the virus possesses sophisticated mechanisms for entering and reproducing in diverse cell types – a characteristic that warrants careful monitoring from a public health perspective.

“It grows equally well in rodent, human, and nonhuman primate (monkey) cells, making it a great candidate for a spillover event,” says Lednicky, a research professor in the UF College of Public Health and Health Professions Department of Environmental and Global Health, in a statement.

Think of viruses like master lock-pickers. Each virus typically has a specific “key” that works on particular “locks” (cellular receptors) found on host cells. What makes GRJV1 unusual is that it seems to have a skeleton key of sorts, capable of breaking into cells from multiple species, including humans, monkeys, rodents, and even bats.

The research team, led by Lednicky and doctoral candidate Emily DeRuyter, wasn’t looking for anything quite so spooky when they began their investigation. Their original goal was to study mule deerpox virus transmission in rodents. Instead, they stumbled upon something potentially more concerning – a virus that seems remarkably adept at crossing species barriers.

When GRJV1 infects cells, it creates a disturbing scene under the microscope. Infected cells merge into giant multi-nucleated structures called syncytia, develop bubble-like vacuoles in their cytoplasm, and eventually die. In some cell types, like monkey kidney cells, the cells dramatically elongate before their demise – a cellular transformation worthy of a scientific horror story.

To understand just how versatile this virus is, the research team tested it against thirteen different cell lines from various species. These included human lung and cervical cells, monkey kidney cells, hamster cells, and even bat lung cells. The virus successfully infected most of these cell types, though with varying degrees of effectiveness. It seemed particularly fond of human, monkey, and rodent cells, where it caused the most dramatic effects.

While the finding that GRJV1 can infect many different species might sound alarming, DeRuyter emphasizes there’s no need to panic. She draws a parallel to hantavirus, another rodent-borne virus that can cause severe illness in humans but rarely does so because most people have limited direct contact with wild rodents or their waste.

“Humans can develop severe to fatal illness if they get infected by hantaviruses, but so far, those types of infections remain rare and typically occur only among people who come into contact with rodent waste, often through airborne exposure to rodent urine or fecal material,” notes Emily DeRuyter, a doctoral candidate in UF’s Department of Environmental and Global Health.

The virus’s genetic makeup reveals its own fascinating story. Its genome contains ten genes, including some unique features that set it apart from its viral relatives. One particularly interesting aspect is its ability to edit its own genetic material during replication, a trick that allows it to produce different proteins from the same genetic template – like getting multiple dishes from a single recipe by making small modifications.

This discovery underscores the importance of viral surveillance in wildlife populations, especially in areas where animals and humans live in close proximity. As human expansion into wildlife habitats continues, the chances of encountering new viruses increase. Finding and studying these viruses before they potentially cause problems is crucial for preparedness – like having an advance warning system for potential threats.

The researchers emphasize the need for further studies to determine whether GRJV1 causes illness in rodents, other small animals, or potentially humans. They’re particularly interested in determining if the virus has already affected humans in Gainesville and the rest of Florida, though no cases have been documented yet.

So, what of Pepper, the black cat whose hunting prowess led to this discovery? True to the resilient nature of cats that have evolved to hunt rodents, he showed no ill effects from his encounter with the virus-carrying mouse. While this is reassuring, the researchers note that further testing is needed to understand how the virus might affect pets and humans.

“We were not anticipating a virus of this sort, and the discovery reflects the realization that many viruses that we don’t know about circulate in animals that live in close proximity to humans,” says DeRuyter, adding, “And indeed, were we to look, many more would be discovered.”