Dr. Johannsen received his medical degree from Harvard Medical School in 1995. After completing a medical residency at Brigham and Women's Hospital and an infectious disease fellowship in the combined BWH/MGH program, he trained in the lab of Elliott Kieff to study Epstein-Barr virus (EBV). He joined the University of Wisconsin faculty in 2011. His research interests include understanding the mechanisms by which EBV nuclear proteins allow the virus to establish life-long infection and contribute to human disease, particularly in persons with compromised immunity.