DNA Polymerase in Virions of a Reptilian Type C Virus

A study was made of the DNA polymerase of reptilian type C virus isolated from Russell's viper spleen cells. Simultaneous detection experiments demonstrated the presence of 70S RNA and RNA-dependent DNA polymerase activity in reptilian type C virions. The endogenous activity was dependent on the addition of all four deoxynucleotide triphosphates and demonstrated an absolute requirement for a divalent cation. The reptilian viral DNA polymerase elutes from phosphocellulose at 0.22 M salt. In this respect, it is similar to the avian (avian myeloblastosis virus; AMV) viral enzyme but is different from the mammalian (Rauscher leukemia virus; RLV) viral enzyme which elutes at 0.4 M salt. The molecular weight of the viper DNA polymerase as estimated from glycerol gradient centrifugation is 109,000. It is a smaller enzyme than the AMV DNA polymerase (180,000 daltons) and somewhat larger than the RLV enzyme (70,000 daltons). A comparison of other properties of the type C reptilian DNA polymerase with the enzyme found in other type C oncogenic viruses is made.