Protein Sciences Corp., of Meriden, Conn.; UNM Pharma Inc., of Akita, Japan; and IHI Corp., of Tokyo, said they entered an agreement to assess the feasibility of sourcing the active ingredients of Flublok influenza vaccine from Japan. The drug substances would be manufactured at the Gifu (Japan) plant of Unigen, a subsidiary of UMN Pharma in which IHI holds 50 percent of the common shares.