"Gain-of-function" refers the genetic modification of a virus to increase its ability to infect human tissue. An article published in 2015 stirred debate about this risky line of research. See "Engineered bat virus stirs debate over risky research", published in Nature, a prestigious scientific journal. The research was conducted at the University of North Carolina at Chapel Hill ... despite the fact that the US government had imposed a ban on such research in 2014. Zhengli-Li Shi, the "bat lady" who headed up the Wuhan bio-lab, is listed along with UNC researchers as a co-author of the article.
The article notes that the gain-of-function research was funded by grants from the National Institute of Allergy & Infectious Disease (under Dr. Fauci's leadership), other NIH entities, the National Natural Science Foundation of China, and USAID. In other words, your tax dollars were hard a work creating highly infectious, horseshoe-bat coronavirus chimera. Thanks, Dr. Fauci, and thank you, UNC Chapel Hill. "A SARS-like cluster of circulating bat coronaviruses shows potential for human emergence", published in Nature Medicine, one of Nature's research journals.
After the GOF ban became effective, Fauci's NIAID and other US government agencies provided funding for such research at Dr. Zhengi-Li's lab in Wuhan. There are many published papers in the scientific literature that document horseshoe-bat coronavirus research that involves genetic manipulation.
Bingo. Fauci is now in CYA mode.