In Vitro Growth Characteristics of Monkeypox Virus 1

Summary A one-step growth study in CV1 cells indicated that infectious virions of MPV were synthesized intracellularly by 8 to 9 hr after infection; whereas cell-free virus and HA developed at later, but variable, stages of the growth cycle. Viral antigen(s) detected by immunofluorescence appeared 2 to 3 hours earlier than infectious virus. These data indicate that MPV is similar to vaccinia and variola viruses in respect to the time course of in vitro intracellular multiplication and release of virus, in cytological alterations and in the intracellular development of viral antigens.