Hepatitis B virus
Speaking of Alter's long research career at the time of the 2000 Lasker Award, Harvey Klein, chief of the Clinical Center Transfusion Medicine Department noted, "As a young research fellow, Dr. Alter co-discovered the Australia antigen, a key to detecting Hepatitis B virus. For many investigators that would be the highlight of a career. For Dr. Alter it was only an auspicious beginning."