WASHINGTON — Kansas Sen. Roger Marshall introduced a bill that would prevent the government from funding a controversial type of research scientists sometimes use in an effort to better understand diseases. The bill, which would bar what is known as gain-of-function research, is Marshall’s latest attempt to draw attention to the uncertain origins of COVID-19. The issue has become a centerpiece of his legislative priorities in his first year as a U.S. senator. In gain-of-function research, scientists make a virus more powerful. It can be used to understand how a virus mutates, which could then ...