HOUSTON : Scientists have laid out an approach to block a protein that the novel coronavirus uses to cut and disable crucial components of the immune system and to produce copies of itself, an advance that may lead to new drugs against covid-19.The researchers, including those from the University of Texas Health Science Center at San Antonio (UT Health San Antonio) in the US, developed two molecules that inhibit the molecular "scissor" enzyme used by the coronavirus called SARS-CoV-2-PLpro.According to the study, published in the journal Science, SARS-CoV-2-PLpro promotes infection by sensing and processing both viral and human proteins."This enzyme executes a double-whammy," said study senior author Shaun K.