Purification of Pox Viruses by Density Gradient Centrifugation

Abstract

Rabbit pox virus grown in tissue culture cells and vaccinia virus grown on rabbit skin have been purified as follows. The virus was sedimented and washed once by centrifugation to provide a tenfold virus concentrate. This semi-purified material was layered on top of a sucrose density gradient and centrifuged to produce a zone of virus separated from zones of impurity. Sucrose was removed from the purified virus suspension by thorough washing in the centrifuge. About 40% of the original infectivity was recovered in the purified material which consisted almost entirely of virus particles when examined in the electron microscope. Control experiments indicated a maximum of 5% protein impurity. Almost complete separation of vaccinia haemagglutinin and virus was obtained.