New pox virus makes squirrel ill

In the Berlin area rampant disease is caused by unknown poxvirus species

Squirrel in the city park - the new pox virus still seems to be rampant, especially in the Berlin Rarum. © Ray eye / CC-by-sa 2.0
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Deadly danger: A previously unknown pox virus makes squirrels ill in Germany. Especially young animals develop inflammation of the ears and extremities and can even die from it. Genetic analysis has now revealed that a previously unknown type of poxvirus causes this disease. For infection researchers this is a small sensation. However, the "Berlin squirrel virus" seems to be harmless to humans, as the researchers explain.

The European Red Squirrel (Sciurus vulgaris) is common in us and in almost all of Europe. Even in big cities you can see the croissants in parks and gardens. But now a strange disease is raging among them: For several years, young red squirrels with severe inflammation of the hands, feet and ears have been found in the Berlin area, without the cause was known.

Enigmatic inflammations

"The little ones can not hold on anymore because their little fingers stick together. The wounds are so painful that the animals often die in shock, "says Tanya Lenn of the Squirrel Help Berlin / Brandenburg, which saw many squirrels by intensive care to get well again. "If they are discovered too late, despite all efforts, not all animals will succeed."

Some of the deceased animals were handed over to the Leibniz Institute for Zoo and Wildlife Research (IZW) for pathological examination. The responsible wildlife pathologist, Gudrun Wibbelt, found in all animals profound skin inflammation, which were complicated by colonization of bacteria and yeasts. "The most important feature of the diseased skin was the rounded inclusions in the skin cells, which were visible in the microscopic examination, " explains Wibbelt.

Squirrel with poxvirus lesions Gudrun Wibbelt / Leibniz-IZW

Remarkable viruses

Using the electron microscope, the researchers were able to detect virus particles in these inclusions. In all the squirrels examined, the same viruses were visible in the electron microscope. The shape and size of these viruses strongly reminded scientists of cowpox viruses, they report. To clarify the suspicion, samples were sent to the consultation laboratory for smallpox viruses in the Robert Koch Institute (RKI). display

However, to the great surprise of the researchers, molecular biology analyzes did not yield a positive result none of the known animal poxvirus species were involved. Subsequently, RKI researchers isolated the virus and deciphered the complete genome of the bred viruses. The genetic information of the virus compared them again with those of all known poxviruses.

A new poxvirus

The result: The Berlin Eichhørnchenvirus is a new type of poxvirus, which is only remotely related to the other poxviruses. "The discovery of a novel smallpox virus is a small sensation among scientists who deal with smallpox viruses, and is all the more remarkable when something like this happens in front of your own door", explains Wibbelt.

The researchers suspect that this new poxvirus has circulated among the squirrels in Berlin for several years. They are now working to investigate and characterize this virus more closely. Reassuring: "The virus seems to specifically attack squirrels so that infections in humans or pets are not to be expected, " says Wibbelt. Because none of the helpers, who regularly fell ill and killed dead squirrels, have been infected so far.

Skin diseases caused by another squirrel pox virus have been known for a long time in red squirrels in the UK. The pathogens are there responsible for the regional eradication of this wild animal species. The carriers of this other type of virus are the large gray squirrels, which were imported from North America to England in the late 19th century. (Emerging Infectious Diseases, 2017; doi: 10.3201 / eid2310.171008

(Forschungsverbund Berlin eV, 09.08.2017 - NPO)