The Bats Behind the Pandemic From Ebola to Covid-19, many of the deadliest viruses to emerge in recent years have the same animal source. By Matt Ridley, 4/9/20, Wall St. Journal [...] Then in 2016, Ralph Baric & colleagues at UNC Chapel Hill showed that the same bat virus could infect live mice that had been engineered to express the human gene for the ACE2 receptor. The virus was ?poised for human emergence,? as the title of Dr. Baric?s paper put it.
[...] There are good reasons why bats spread so many viruses. Bats are long-lived mammals, like us, and live in large crowds, like us?ideal for spreading respiratory infections in particular. One bat roost in Texas houses 20 million bats at certain times of year, a concentration of mammals paralleled only by people in cities. There are lots of different species?one-quarter of all mammal species are bats?so they have lots of different viruses. And they fly, carrying diseases long distances, allowing viruses to indulge in ?host-shifting? between bat species. This especially suits viruses that can ?recombine? with related strains, like coronaviruses.
It is not yet clear why horseshoe bats, in particular, are so infested with coronaviruses. These are average-size bats, distinguished by large, pointed ears and weird little sonar dishes known as nose-leafs, the outer part of which are often shaped like horseshoes. There are at least 100 species, many of which look very alike. Absent from the Americas, they are found all over the tropics of the Old World and in some warm temperate regions. They seem to be fond of living in caves and gathering in large aggregations. [...]