Biophysical properties of coronavirus strain OC 43.

Coronavirus OC 43 from suckling mouse brains was subjected to sucrose density gradient centrifugation. Maxima of complement fixing (CF) activities occurred in the ribosomal (density 1.14) and mitochondrial (density 1.19) fraction which contained incomplete, damaged virus particles. The haemagglutinating (HA) activity was associated with the microsomal soluble protein fraction displayed no antigenic activity. The isolated purified virus proved to be very unstable.