(Order of authorship in the original publication: Blumberg, Alter, Visnich.) Discovery of Australia antigen, hepatitis B antigen, Aa, later called HBsAg.  Blumberg received half of the Nobel Prize for Medicine in Biology in 1976 for the discovery of the antigen, for discovery of the hepatitis B virus, and for the discovery/ invention of the hepatitis B vaccine— the first cancer vaccine.  See B. S. Blumberg, Hepatitis B: The Hunt for a Killer Virus (Princeton: Princeton University Press, 2002.)

Particles with the appearance of a virus were detected by electron microscopy in the serum of individuals with Au. These were subsequently shown to be the surface antigen particles, different from the whole virus particles. Blumberg's discovery of the Australia antigen in 1965 may technically be considered the discovery of the hepatitis B virus, but at the time of that discovery its connection with a virus was speculative. 

First description of the hepatitis B vaccine, the first cancer vaccine, US patent 3636191A. Millman and Blumberg discovered that the blood of individuals carrying the hepatitis B virus contained particles of the outside coating of the virus. This coating, hepatitis B surface antigen (HBsAg), is not infectious; however, HBsAg can provoke an immune response. To develop a vaccine, Millman and Blumberg invented a method of detaching the coatings from the virus. See B. S. Blumberg, editor, Hepatitis B and the Prevention of Primary Cancer of the Liver. Selected Publications of Baruch S. Blumberg. (2000). See also I. Millman, T. Eisenstein & B. Blumberg, Hepatitis B: The Virus, the Disease, and the Vaccine. (New York: Plenum Press, 1984). 

Purification of the Australia antigen and investigation of its physical properties. (Order of authorship in the original publication: Millman, Loeb, Bayer, Blumberg.)

Blumberg shared the 1976 Nobel Prize in Physiology or Medicine with D. Carleton Gajdusek "for their discoveries concerning new mechanisms for the origin and dissemination of infectious diseases." See also Nos. 3666.4, 6840, 6841.