With its acquisition of Subintro Ltd., Rigimmune Inc. put a building block in place to further its development of stem-loop RNA therapeutics that selectively activate the innate immune sensor RIG-I. Subintro specializes in development and delivery of antiviral therapeutics for respiratory diseases caused by RNA viruses, including influenza, rhinovirus and SARS-CoV-2. Subintro’s technology allows the company to consider topical and nasal delivery.