Enumeration of Vaccinia Virus Particles in Crude Extracts of Infected Tissues by Electron Microscopy.

Abstract

Vaccinia virus particles were counted accurately and reproducibly in dilutions of 10% extracts of infected egg chorioallantoic membrane and rabbit skin by the agar sedimentation method. Standard deviation of these counts ranged from 10 to 14%. Comparison with concentrated, purified vaccinia virus, of counting by sedimentation and spray droplet methods gave results which are in excellent agreement. Various factors important in the accurate counting of vaccinia virus in crude tissue extracts are discussed.