Protection of Vaccinia from Heat Inactivation by Nucleotide Triphosphates

Abstract

The presence of adenosine triphosphate, guanosine triphosphate, cytosine triphosphate, or uridine triphosphate reduced the rate of inactivation of vaccinia when heated at 50 C. The virus-associated nucleoside triphosphate phosphohydrolases (adenosine triphosphatase, guanosine triphosphatase, cytosine triphosphatase, and uridine triphosphatase) and ribonucleic acid polymerase were also protected from heat inactivation by these compounds. These obervations are best explained by postulating that ribonucleoside triphosphates bind to enzymes in the virus particle, and that these enzyme-substrate complexes are more resistant to thermal denaturation than are the enzymes without their substrates. The kinetics of heat inactivation of the vaccinia ATP phosphohydrolase activity is biphasic, suggesting that there are two proteins in the vaccinia particle that have this enzyme activity but they have different kinetics of heat inactivation. Any of the vaccinia-associated nucleotide phosphohydrolase activities are protected from heat inactivation by the presence of any one of the respective nucleoside triphosphates. This observation suggests that there is a single enzymatic site in vaccinia that is able to react with any ribonucleoside triphosphate. Wallis, Yang, and Melnick (14) reported that the rate of heat inactivation of vaccinia is reduced by the presence of 2.0 M NaCl or 50%

Preparation and evaluation of a noninfectious monkey pox virus vaccine

“…Virus infectivity assay. MPV infectivity was quantitated by a modification of a procedure described by Munyon et al (9). Briefly, sonically treated preparations of MPV were diluted in serumfree minimal essential medium (MEM), and 0.2 ml of these dilutions was inoculated on LLC-MK2 cells growing in 60-mm petri dishes and allowed to adsorb for 1 h at 36°C.…”