Dive Brief:Flagship Pioneering on Tuesday launched Prologue Medicines, a new biotechnology startup aiming to make drugs by closely studying the proteins of viruses.Prologue is starting out with $50 million and what it claims is the largest known database of viral protein structures. With the help of machine learning tools, the startup plans to mine that database for proteins that can point the way to new medicines.The startup hasnt said which specific diseases it will go after first or identified a lead program. CEO and Flagship origination partner Lovisa Afzelius said in a statement that the companys approach could unearth drugs across nearly any therapeutic area. Prologue will use the initial funding to hire staff and build up research and development capabilities, the company said.Dive Insight:Flagship is known for betting on drugmaking platforms. The firm created messenger RNA specialist Moderna, brain drug developer Denali Therapeutics and many other companies touting new ways to find medicines. It currently has more than 40 startups in its portfolio.The firm has kept its focus even as investors have shifted attention to safer bets, and as some of its more mature companies have faltered on the public markets. In the last year alone, Flagship has unveiled startups like Empress Therapeutics, Metaphore Biotechnologies and Quotient Therapeutics, which are advancing different drug discovery approaches. Its also putting together a $3 billion fund and hired several more origination partners tasked with growing new platform companies.Prologue is next in line. The company was formed by Afzelius and Flagship senior principal Theonie Anastassiadis, who previously teamed up to found RNA drug startup Alltrna. With Prologue, the two see an opportunity to develop biologic medicines for a wide range of diseases, with an initial focus on immunology, oncology and metabolic disorders, Anastassiadis said.Viruses are rapidly evolving and, while doing so, equip themselves with new powers, such as ways to evade the immune system or better target specific cell types, according to Anastassiadis. By systematically exploring the millions of different proteins viruses use, Prologue intends to better understand their function and application to disease.The wealth of viral sequences, combined with advances in machine learning, led us to a venture hypothesis of 'what if we could actually leverage these viral proteins that have these unique features and turn them into medicines?' said Anastassiadis.The company plans to fill out its leadership team and build its pipeline with an eye towards the clinic, Anastassiadissaid.Editors note: This story has been updated to clarify the attribution to quotes from Theonie Anastassiadis. '