As the coronavirus continues to evolve, the scientific and public health focus has been on new variants in which some mutations make the virus more infectious, or even, can be, more deadly.
These changes in the virus are what scientists call point mutations, replacing a small fragment of the genetic code with another. Coronaviruses, as a group, are not known to mutate rapidly, but the pandemic caused by the SARS-CoV-2 virus means that millions and millions of people are infected by billions and billions of viral particles, offering countless chances for change.
There is, however, another more significant way of altering coronaviruses. Individual viral particles exchange larger sections of genetic material with another virus. If two different types of coronavirus inhabit the same cell, the result may not be a new variant, but a new species.
Three researchers at the University of Liverpool who wrote in the journal Nature Communications predicted, based on a computer analysis, that such events are much more likely than previously thought, and recommended monitoring target species to observe the possible appearance of new coronavirus diseases.
The work pointed in some directions where scientists are already alert. They identified the smaller Asian yellow bat and the larger, intermediate horseshoe bats as animals where recombination would be more likely to occur. But his analysis also pointed to animals that scientists have been focusing less on, such as the common pig, as a creature to be monitored.
Marcus SC Blagrove, a virologist who wrote the report along with Maya Wardeh, who specializes in computer analysis of the spread of disease in animals, and Matthew Bayliss, a veterinary epidemiologist, said coronaviruses were known to “exchange large chunks throughout the place”.
The emergence of new diseases through this process is not common because an animal needs to be infected with two different types of coronavirus at the same time.
Jeremy Luban, a virologist at the University of Massachusetts, said that this double infection with two types of virus that replicate in a cell has not yet been documented in humans. But it is exactly this recombination as SARS appears to have emerged, and the researchers believe that SARS-CoV-2 may also be the result of combining two viruses.
Dr. Luban said that he thinks “this kind of work is extremely important” because it can generate surprising discoveries that can be followed by experiments and fieldwork.
The group of researchers in Liverpool used a type of computer analysis called machine learning to look at a number of different data points, including the genetic structure of coronavirus and mammalian species, as well as their behavioral similarity and geographic proximity to arrive at predictions of which animals were most likely to harbor the greatest number of coronaviruses.
They predict that 40 times more mammalian species can be infected with four or more different types of coronavirus than those now known, and that up to 126 mammalian species may be susceptible to SARS-CoV-2 infection.
As a reality check, they pointed out that their analyzes correctly predicted some known associations of animals and viruses. The modeling highlighted palm civets, the animal from which SARS appeared to have spread to humans as a potential hot spot for coronavirus evolution.
Above all, they warned that the possibility of recombination resulting in the emergence of some dangerous new coronavirus is highly underestimated.