Growth kinetics of Yaba tumor poxvirus after in vitro adaptation to cercopithecus kidney cells

Yaba tumor poxvirus has been adapted to continuous in vitro cultivation in monolayers of cercopithecus kidney cells. At 35 C, the minimum replicative cycle, after synchronous infection of CV-1 cells with multiplicity of infection of 135 focusforming units per cell, was 35 hr; however, maximum virus yields were not obtained until 75 hr postinfection (PI). Cytoplasmic incorporation of (3)H-thymidine [viral deoxyribonucleic acid (DNA) synthesis] was detected 3 hr PI and was preceded by synthesis of nonstructural associated antigens (YS). Synthesis of YS antigens was not inhibited by the DNA inhibitor, arabinofuranosyl cytosine (ARA-C). Synthesis of at least two virion structural antigens, although not detected by immunofluorescence until 2 hr after the onset of DNA synthesis, occurred in the presence of ARA-C, indicating potential translation of these structural antigens from parental DNA. The first progeny DNA was completed by 20 hr PI but was not detected in infectious form until 35 hr PI. The maximum rate of progeny DNA completion occurred between 20 and 30 hr PI. DNA synthesis continued 45 to 50 hr PI. The adapted virus retained its oncogenicity and, like the wild type, replicated better at 35 C than at 37 C. A synthetic step associated with viral DNA synthesis appears to be temperature-sensitive.