What other coronaviruses tell us about SARS-CoV-2
>  In cats, for example, infection with feline enteric coronavirus may last for months or longer. When this happens, the virus mutates so much that its very nature seems to change. What starts out as a relatively mild gastrointestinal infection eventually causes serious peritonitis (inflammation of the membrane lining the abdominal wall) in some animals. Examining the virus at this point in the infection, researchers found that the mutations had resulted in the emergence of a related virus, feline infectious peritonitis virus — and this one has a higher fatality rate.Can someone explain this to me, are they saying that the virus mutated into another virus? What conditions would it need to be a new virus rather than a variation of the original one?