Structural polypeptides of three rhinoviruses

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.

mentioning

confidence: 99%

Properties and origins of infectious rhinovirus type 14 particles of different buoyant densities

Gauntt¹,

Griffith²,

Sauck³

et al. 1975

“…Previous studies have shown that picornaviruses generally are composed of multiple polypeptides (2,14,15,16). Quantitative estimates of the molar ratios of the structural polypeptides have been made for ME virus (22) and a bovine enterovirus (14).…”

mentioning

confidence: 99%

Polypeptide Composition of Poliovirions, Naturally Occurring Empty Capsids, and 14 S Precursor Particles

Phillips

Fennell

1973

The three serotypes of poliovirus were compared with respect to their polypeptide composition. Type 1, 2, and 3 strains were clearly different from each other in the electrophoretic mobilities of their larger structural polypeptides. Some of the viral polypeptides formerly identified as single peaks (e.g., VP 2) were shown to contain multiple components, indicating that purified virions contain at least six polypeptides. Three type 1 strains were indistinguishable in their viral polypeptides. A quantitative estimate was made of the polypeptide composition of the type 1 Mahoney poliovirion, as well as of naturally occurring empty capsids and 14S precursor particles. The data are discussed in light of the antigenic differences among polioviruses and the possible modes of virion morphogenesis.

“…By now several spherical viruses and empty capsids have been found to contain nonidentical polypeptide chains (1,12,17,18,21,24,25,27,28,30,32,34) apparently in equimolar ratios. Picornaviruses of various mammalian hosts are heavily represented on this list (17,18,24,25,27,30,32,34), but the list also includes an RNA insect virus (21), as well as two DNA bacteriophages (1, 28) and an RNA plant virus (12). The insect virus may be structurally equivalent to the mammalian picornaviruses.…”

mentioning

confidence: 99%

Structure of Isometric Viruses Containing Nonidentical Polypeptide Chains

Dunker

1974

The theory of Caspar and Klug (1962) for the structure of isometric viruses has been generalized to the case in.which the identical repeating unit is composed of n nonidentical polypeptide chains. This modified theory accounts for the structure of picornaviruses, the lambda phage head, cowpea mosaic virus, and 4X174, while at the same time conserving the principle of having identical subunits in identical environments. Furthermore, the modified theory suggests amending the triangulation number to T[n] for capsids with n nonidentical polypeptide chains as the repeating unit.