A study submitted for publication in April 2020 from the Wuhan Institute of Virology (WIV) used transgenic humanised mice, engineered so their lungs express ACE2 receptors.  These mice aid as animal models, representing a human subject and are used to study their susceptibility to viruses.

In a comprehensive Vanity Fair article, it was noted that working this study timeline backwards, it was estimated that sometime in the [US] summer of 2019 [winter in Australia JUNE], “months before the virus first appeared in Wuhan, the Wuhan Institute of Virology was growing human lungs, in mice, for the purpose of testing out the human infectivity of coronaviruses.” [1]

A paper by Ben Hu suggests the mice were created in 2018. [3]

The NSC officials who uncovered this important evidence in favor of the lab-leak hypothesis began reaching out to other agencies, but were immediately “dismissed” with a very “negative” response. Throughout 2020, the notion that the novel coronavirus leaked from the WIV lab was taboo, by anyone!

Further, the “NSC officials were left wondering: Had the Chinese military been running viruses through humanized mouse models, to see which might be infectious to humans?

Did the Chinese engineer these mice, or were they given them by the US? [2]