SUMMARYDense poliovirus particles (buoyant density I"44 g/ml in CsC1) isolated from infected HeLa cells contain the normal four structural polypeptides VPI to VP4, and 35 S poliovirus RNA. In addition, small amounts of VPo and single-stranded RNA sedimenting slower than the poliovirus genome are present. Dense particles have a low specific infectivity, are neutralized by type-specific poliovirus antisera, and are detected during growth as early as normal virus but disappear when virus production stops. They appear to represent a different, more open, conformation of the normal virus capsid.
SUMMARYDense poliovirus particles (DP) differ in buoyant density, sedimentation coefficient and lability from standard poliovirus particles. Dense particles band at a density of I'44 g/ml in isopycnic CsC1 gradients and sediment in sucrose gradients at 22oS. However, when DP are centrifuged in sucrose gradients containing 1.5 M-KCI, NaCI or LiC1, two types of particles are observed, one sedimenting at z2oS and the other at I6oS. Particles sedimenting at 2zoS are converted into particles sedimenting at I6oS by incubation at 37°C in P5 M-KC1.The high buoyant density seems to be correlated with the high lability of DP. Dense particles are extremely labile in isotonic phosphate-buffered saline. Their degradation proceeds through an RNA-containing particle lacking polypeptide VP4, to RNA and empty capsids.
SUMMARYProperly purified preparations of poliovirus particles are practically free of o-galactose and N-acetyl-D-glucosamine. These sugars, however, are found in crude virus preparations, obtained by high and low speed sedimentation and by CsCl-gradient fractionation from infected HeLa cells. They are separated from the virus particle by extraction with chloroform and subsequent isopycnic sedimentation of the virus preparation. Since o-galactose and N-acetyl-o-glucosamine are regular constituents of glycoproteins, the absence of significant amounts of these sugars demonstrates the lack of glycoproteins in poliovirus particles.Radioactive monosaccharides are recommended for the detection of cellular impurities in carbohydrate-free viruses.A simple and rapid method for the purification of large quantities of poliovirus by 'precipitation' with polyethylene glycol, resuspension in CsC1 solutions, extraction with chloroform and isopycnic sedimentation is described.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.