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 covid19the 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 sarscov2plproaccording to the study published in the journal science sarscov2plpro promotes infection by sensing and processing both viral and human proteinsthis enzyme executes a doublewhammy said study senior author shaun k olsen associate professor of biochemistry and structural biology at ut health san antonioit stimulates the release of proteins that are essential for the virus to replicate and it also inhibits molecules called cytokines and chemokines that signal the immune system to attack the infection olsen saidsarscov2plpro cuts human proteins ubiquitin and isg15 which help maintain protein integrity by acting like a molecular scissor he explainedthe scientists developed the inhibitors which are very efficient at blocking the activity of sarscov2plpro yet do not recognise other similar proteins in human cellsthis is a critical point the inhibitor is specific for this one viral enzyme and doesnt crossreact with human enzymes with a similar function he addedthe researchers said this specificity would be a key determinant of the therapeutic value of the approachwhen the scientists compared sarscov2plpro against similar enzymes from coronaviruses of recent decades such as the 200203 sars pandemic virus they learned that it processes ubiquitin and isg15 much differently than its counterpartone of the key questions is whether that accounts for some of the differences we see in how those viruses affect humans if at all olsen saidby understanding similarities and differences of these enzymes in various coronaviruses the researchers said it may be possible to develop inhibitors that are effective against multiple virusesolsen said these inhibitors could also be potentially modified when other coronavirus variants emerge in the future