Researchers have identified the molecular `switch` that directly triggers the body`s first line of defence against pathogens, more accurately known as the body`s "innate immunity". They found that this molecule -- called Bruton`s tyrosine kinase (BTK), when switched on, activates the production of interferons, a potent class of virus killers that enables the body to fight deadly dengue and flu viruses. While there are anti-viral drugs to treat flu, the high rates of mutation that characterise flu virus have made it difficult to treat with one universal drug or vaccine, according to a statement of Bioprocessing Technology Institute (BTI), under the Agency of Science, Technology and Research (A*STAR), Singapore. As for dengue, there are currently no clinically approved vaccines or cures either. This discovery of BTK`s role as a critical `switch` that boosts the body`s anti-viral response, paves the way for developing anti-viral drugs that target the BTK `switch` to fight infectious diseases. "We are very excited because this is the first time that the link between BTK and its critical role in the immediate anti-viral responses of the immune system, triggered in response to invading viruses like Dengue, is definitively demonstrated," said Koon-Guan Lee, study co-author from BTI. Kong-Peng Lam, professor and acting executive director of BTI, said: "This study adds new insights to the understanding of how the body`s innate immunity is triggered to create an effective immune response."