Quantitative assay of paravaccinia virus based on enumeration of inclusion-containing cells.

Bovine paravaccinia virus produces cytoplasmic inclusion bodies on infection of bovine embryonic kidney cells; these were easily recognized when stained with acridine orange or May-Grünwald-Giemsa stain. The inclusions could be shown to contain newly synthesized deoxyribonucleic acid by autoradiography. Counts of inclusion-containing cells decreased when virus suspensions were treated with immune serum before being used to inoculate cell cultures.