Antigens from Vaccinia Virus Particles

Soluble material extracted from purified vaccinia virus particles produced eight precipitin lines with antiserum by immunodiffusion. The material contained about 20 % of the viral nitrogen and was obtained by extraction with alkaline buffers up to pH 10·5, by prolonged autolysis or, more conveniently, by digestion with trypsin. It appeared to originate mainly from the virus surface but, as it also contained about 5 % of the viral DNA and a small proportion of the virus particles were converted to ghosts, some of the precipitin lines probably represented internal components of the virus. When more material (up to 75% of the viral-N) was extracted no further precipitin lines were detected but some immuno-specificities may have been destroyed. Serial extractions at increasing alkaline pH values separated the antigens from most of the viral DNA and indicated that the ‘nucleoprotein antigen’ of earlier workers was probably an artifact.