Dog virus made cat killers more aggressive
The cause of a mysterious and deadly cat epidemic in Cyprus has been found: A cat coronavirus whose genetic material contains parts of an extremely aggressive dog virus.
A genetically modified coronavirus is probably behind a mysterious epidemic that killed thousands of cats in Cyprus in the summer of 2023. A significant part of its genetic material apparently comes from a hyper-aggressive variant of a coronavirus that occurs in dogs, reports a research group led by Christine Tait-Burkard from the University of Edinburgh. As she writes in a preliminary publication, the gene exchange also affects the spike protein of the virus called FCoV-23, which may explain some of the altered viral properties. The cats were suffering from the often fatal disease Feline Infectious Peritonitis (FIP), which is caused by a coronavirus but is not normally contagious. However, during the outbreak in Cyprus, the pathogen spread rapidly between the cats and triggered an epidemic.
The research group suspects that the exchanged spike protein is the reason that the non-communicable disease FIP is contagious in this case. The virus from which it originates affects many very different cell types in dogs. It is therefore possible that FCoV-23 - unlike the normal trigger of FIP - can infect cells in the intestine and is excreted in the faeces. In addition, according to the research team, the protein does not have a special "predetermined breaking point" at which it has to be cut by an enzyme before infection. As a result, it is presumably more stable in the environment and able to infect other cats for longer.
Fundamentally new about FCoV-23 is that it appears to cause the severe disease FIP directly. Normally, FIP only develops when an actually harmless feline coronavirus mutates in the intestine into a very pathogenic but no longer infectious virus. However, it is still completely unclear why this is the case. It is also unknown why the new virus apparently causes a much higher rate of neurological symptoms than is seen in classic FIP. The working group now wants to clarify how the new genes are linked to altered symptoms. In addition, the experts now want to systematically test cats for FCoV-23 in order to determine the true incidence. This is because many fundamental questions remain unanswered about the outbreak of the disease itself.
So far, it is not even clear how large the outbreak in Cyprus actually was - initial alarming figures of 300,000 cats killed proved to be completely exaggerated. It is now thought to be several thousand; it is not known how many cats die of FIP on the island in a normal year. It is also unclear how the gene exchange between the two viruses came about, which ultimately resulted in FCoV-23. However, the working group points out that cat and dog coronaviruses are known to recombine with each other from time to time - just like coronaviruses of many other species. It may be pure coincidence that an unusually dangerous version of the virus was created during an everyday process.
Spectrum of Science
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© BrindleBerry / Getty Images / iStock (detail) The cats in Cyprus were suffering from the often fatal disease feline infectious peritonitis (FIP)
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