How does Jahrling text the blood?

Jahrling uses blood serum from three individuals who were infected with a filovirus strain: Shem Musoke for Marburg, Mayinga N. for Ebola Zaire, and Boniface, a man who died from Ebola Sudan. Jahrling combines the monkey cells with blood serum from each individual. If the monkey sample tests positive for one of the three strains, the cells will glow under ultraviolet light.