Colin Carlson, a biologist at Georgetown University, became concerned about mousepox.
The virus, discovered in 1930, spreads among mice, killing them with ruthless efficiency. But scientists have never considered it a potential threat to humans. Now Dr. Carlson, his colleagues and their computers are not so sure.
Using a technique known as machine learning, researchers have spent the past few years programming computers to learn about viruses that can infect human cells. Computers have combed through vast amounts of information about the biology and ecology of the animal hosts of these viruses, as well as the genomes and other characteristics of the viruses themselves. Over time, computers began to recognize certain factors that predict whether a virus could spread among humans.
Once the computers were tested against viruses that scientists were already intensively studying, Dr. Carlson and his colleagues applied them to the unknown, eventually compiling a short list of animal viruses that could cross the species barrier and cause epidemics in humans.
In recent runs, algorithms have unexpectedly placed the mousepox virus in the top ranks of dangerous pathogens.
“Every time we use this model, it gets very high,” Dr. Carlson said.
Intrigued, Dr. Carlson and his colleagues dug into the scientific literature. They came across documents about a 1987 outbreak in rural China. Schoolchildren contracted an infection that caused them a sore throat and inflammation of the hands and feet.
Years later, a team of scientists ran tests on throat swabs that were collected during the outbreak and stored. These samples, the group reported in 2012, contained mousepox DNA. But their study attracted little attention, and a decade later, mousepox is still not considered a threat to humans.
If the computer programmed by Dr. Carlson and his colleagues is working, the virus deserves a new look.
“It’s just insane that this gets lost in a huge pile of stuff that public health has to sift through,” he said. “It actually changes the way we think about this virus.”
Scientists have identified about 250 human diseases that arose when the animal virus crossed the species barrier. For example, HIV passed from chimpanzees, and the new coronavirus originated in bats.
Ideally, scientists would like to recognize the next contagious virus before it infects humans. But there are too many animal viruses for virologists to study. Scientists have identified more than 1,000 viruses in mammals, but this is likely a tiny fraction of the actual number. Some researchers suspect that mammals carry tens of thousands of viruses, while others believe the number is in the hundreds of thousands.
To identify potential new spin-offs, researchers like Dr. Carlson are using computers to uncover hidden patterns in scientific data. Machines can focus on viruses that are particularly likely to cause human disease, for example, and can also predict which animals are most likely to carry dangerous viruses that we don’t yet know about.