RILEY, JEAN M. (U.S. Army Biological Laboratories, Fort Detrick, Frederick, Md.), AND MICHAEL D. ORLANDO. Singledose assay technique for variola virus. Appl. Microbiol. 12:7-9. 1964.-A biological assay for variola virus was needed that would (i) require a minimum of time and (ii) have acceptable precision. Preliminary titrations made in 11-day-old embryonated eggs and in suckling mice (6 to 24 ...