Gain-of-function research involves giving a pathogen a new "ability" and is controversial because if a pathogen is mutated to become more infectious or deadly and then escapes from a lab, it could ...

What exactly is gain-of-function research, and is it cause for alarm? Researchers have been modifying viruses for decades—and not always in benign ways.

Gain-of-function research is the serial passaging of microorganisms to increase transmissibility, virulence, immunogenicity, and host tropism.