Isopycnic centrifugation of rhinovirus type 14 (RV14), purified from infected HeLa or KB cell cultures, into CsCl gradients resolved two bands of infectious virus particles with buoyant density values of 1.409 +/- 0.007 (H virus) and 1.386 +/- 0.004 (L virus) g/ml. Only H virus was detected by incorporation of radiolabeled uridine into viral RNA, and H virus accounted for the majority of infectivity in gradients. H and L virus could not be differentiated by plaque morphology, extent of neutralization by RV14-specific antiserum, or particle size. Electron microscope studies showed that most L-virus particles were associated with an amorphous material. Treatment of L virus with proteolytic enzymes or rebanding L virus in CsCl gradients resulted in recovery of the majority of infectivity as H virus. Virus purified from cell-free fluids from infected HeLa or KB cell cultures banded only as H virus. HeLa cell cultures challenged with purified H virus and harvested at 3 h postinoculation for virus purification yielded only infectious H virus. Both H and L viruses were detected in cell cultures that had been challenged with purified H virus and harvested at 12 h postinoculation. The data suggest that H virus represents progeny virus, whereas L virus represents sequestered infectious virus particles which become associated with an amorphous material and do not enter into viral replicative processes.

Rhinovirus type 14 RNA-dependent RNA polymerase complexes were isolated from microsomal and soluble fraction of infected KB cells. Maximum activities were measured at at 6 and 7 hours post inoculation (p.i.) for microsomal and soluble polymerases, respectively. Both polymerase activities are considerably reduced by 8 to 9 hours, p.i., and interval in which the in vivo rate of synthesis of viral RNA is maximal. In vitro RNA products of RNA polymerases in both fractions consist of ribonuclease-sensitive and ribonuclease-resistant RNA of heterogeneous sizes. Detergent treatment of the microsomal RNA polymerase(s) did not affect the total amount of RNA synthesized, the proportion of ribonuclease-sensitive RNA synthesized or the size of the RNA products. The data suggest that RV14RNA polymerase complexes are intially associated with membranes but are then irreversibly released into the soluble phase of the cytoplasm; possible explanations for this phenomena are discussed.

No abstract