Abstract
Ultrastructural studies of simian virus SA12, growing in primary cultures of vervet monkey-kidney cells, have demonstrated a typical papovavirus capsid morphology and a diameter of 43 nm. The cytopathic nuclear characteristics, with the absence of virus crstals and elongated capsid forms, distinguish it from SV40 and the human papovaviruses. Like other papovaviruses, SA12 shows a strong affinity for cellular membranes.