Abstract
Biophysical study of Australia antigen (Au) was made with 5 specimens including 3 plasmas and 2 plasma pools which had been known to be Au carriers. A fraction which could be detected both by complement fixation test and by Ouchterlony double diffusion test was obtained with all of the specimens and this could be banded at a buoyant density of 1.21-1.23g/cm3 in CsCl. In addition, another fraction with a buoyant density of 1.28g/cm3 was recovered from one of the plasma pools. This fraction was detected, however, only by complement fixation test. Electron microscopic study of the latter fraction revealed small particles about 3-4 mμ in diameter, suggesting subunits of known Au antigen particles.
