FOOT-AND-MOUTH-DISEASE VIRUS AND POLIOVIRUS PARTICLES CONTAIN PROTEINS OF THE REPLICATION COMPLEX

Nonstructural proteins 2C, 3CD, 3C, and 3D, and the cellular protein a ctin, are present in highly purified preparations of foot-and-mouth di sease virus (FMDV) and poliovirus. They remain bound in variable amoun ts to the RNAs when the RNAs are extracted from the viruses,vith pheno l or phenol-sodium dodecyl sulfate (SDS) and, for FMDV, when the RNA i s released from the particles by a lowering of the pH below 7. RNA pre pared by these methods is rapidly degraded at 37 degrees C, particular ly in the presence of NH4+ ions, but hydrolysis can be prevented by an tibody against Escherichia coli-expressed 3D, indicating that it is th e RNA polymerase that has nuclease activity, In contrast, virion RNA f rom which the nonstructural proteins and actin have been removed by ex traction with guanidine thiocyanate-phenol-chloroform or proteinase Ii -phenol is stable at 37 degrees C, although its specific infectivity i s lower than that of the RNA extracted with phenol or phenol-SDS. The possible implications of the close association of replication complex proteins with the RNA in virus particles are discussed.