Eclipse products of poliovirus after cold-synchronized infection of HeLa cells

The particles derived from radioactively labeled poliovirus, in cold-synchronized infection of HeLa cells, were studied. After temperatures shift-up, radioactivity was transferred rapidly from the infecting virions (160 S) to 135 S, and from there more slowly to 110 S, a previously unreported eclipse product. Both the 135 and 110 S particles contained RNA, lacked VP4, and were H-antigenic. In the 135 S particles, part of the VP1 complement was lost; in addition to this, the VP2 polypeptide of the 110 S particles was cleaved in situ. The formation of eclipse products was insensitive to cycloheximide. Arildone totally blocked the formation of 135 S particles, but not their further processing.