We have too ample evidence now that the animal that can transport SARS-CoV-2 from point A to point B, and spread it the fastest is a human being. Caged animals of any kind need not apply – and no animal reservoir for the virus has been found, now several months into the investigation. It is not for lack of the Chinese looking - they are far more motivated to understand the genesis of this than anyone.
The "pangolin hypothesis’ was based on faulty molecular analysis of sequence similarity, which turned out to not be that similar at all. That explanation was debunked 2.5 months ago.
I am not a fan of “gain of function” experiments at all, but the work of Zhengli and colleagues has shown that direct bat to human Coronavirus infection is possible. We are certain of it for Ebola.
The overall sequence of SARS-CoV-2 is closest to Yunnan isolates – only a bit appears to come from a virus that is HKU9-like. So it most likely came from Yunnan – but the outbreak occurred 700 miles away in Wuhan, not in Yunnan. Not along the way there either. The sole human traveler on high speed train while still in incubation is the best fit to the known information, in my view. Ockham’s razor (note spelling).
Microbats, Macrobats and Bat Coronaviruses have been circulating through the Karst limestone formations in the south of China, that stretches from southeast Yunnan to western Guangdong, far longer than the Chinese people have been in existence. That is saying a lot, but it is a truth attested to by the very wide varieties found there of both hosts and viruses…Human Coronavirus disease out of that environment has been an accident waiting to happen – and still is. Emergence happens.
About an hour from this writing, I can go on my porch and watch a flight of microbats rise from hollow trees in the wetland forest at the rear of my property, to skim the headwaters of Gum Creek for their nightly meal of insects. It is the peril of being a virologist that there are times I wonder about their virome.
But right now, the grocery store is a far more dangerous place than my forest. We would all instinctively like to blame that on someone, somewhere. The truth is that every virus of human beings represents a past accidental emergence, an innocent wrong place, wrong time, thing.
Bill Gallaher