The PRRA polybasic furin cleavage site somehow managed to get into just the right part of the virus structure so that it was really effective at getting into hu

The PRRA polybasic furin cleavage site somehow managed to get into just the right part of the virus structure so that it was really effective at getting into humans cells (but not at infecting bats, or pangolins for that matter). The closest known relative (itself a major discovery) was somehow forgotten about for the last five or so years, and by the time news of it came to public attention, it just so happened that all of the physical samples of it had been destroyed I'm starting to become bemused at the people are now talking about the lab origin as having been somewhat obvious all along.