Merck entered a deal to acquire biotech firm Sirna Therapeutics for $1.1 billion. The deal will give Merck access to a new class of medicines based on RNA interference (RNAi) technology. RNAi is a considered a powerful mechanism for inactivating particular genes and is used widely in laboratories to study genetic functions.Both Merck and Sirna are hoping the technique can be harnessed to kill viruses or tumors for instance by “turning off” their genes.“We believe that RNAi could significantly change the way in which we go about discovering and developing drugs, and could become a new way to treat patients with unmet medical needs,” said Merck research president Peter Kim in a statement.