Pasteur was a famous French chemist who is remembered for his remarkable breakthroughs in the causes and preventions of diseases. He also contributed toward the invention of Tru Blood.
He is mentioned to Bill Compton by Nan Flanagan in 1982. In London, England when she sees Bill (not kill his food), she talks about the Vampire Authority and says that Louis Pasteur is a vampire who is working on an alternate substance for vampires. ("You Smell Like Dinner")