181.
Ultrastructural Studies of Hepatitis A Virus by Electron Microscopy
- Cook, E. H.; Bradley, D. W.; Gravelle, C. R.; Maynard, J. E.
Well-defined, core-like structures were visualized in hepatitis A virus particles by a modified microelectron microscopy technique.
182.
Proposal for Numbering Mutants of Avian Leukosis and Sarcoma Viruses
- Vogt, Peter K.; Weiss, Robin A.; Hanafusa, Hidesaburo
A system for the numbering of mutants of avian sarcoma and leukosis viruses is proposed.
183.
Subacute Sclerosing Panencephalitis Measles Virus: Study of Biological Markers
- Hamilton, R.; Barbosa, L.; Dubois, M.
Comparative studies between two measles virus strains isolated from patients with subacute sclerosing panencephalitis (SSPE) and a prototype low tissue culture passage Edmonston measles virus are described. Differences were noted in several properties. The findings described in this report suggest that strains of measles virus associated with SSPE have different biological properties and apparently cannot be distinguished from laboratory and field strains of the virus.
184.
Efficient Filtration and Sizing of Viruses with Membrane Filters
- Ver, Binie A.; Melnick, Joseph L.; Wallis, Craig
Untreated membrane filters retain viruses by adsorption, as well as by physical restriction which occurs when the pore diameter of the filter is smaller than that of the virus particle. As originally recommended by Elford, membranes had to be pretreated with proteinaceous material to preclude virus adsorption. However, coating materials that prevent adsorption of certain viruses do not necessarily prevent adsorption of other viruses. In contrast to proteins, salts enhance virus adsorption. Viruses treated with sodium lauryl sulfate to reduce the surface tension, or purified viruses in distilled water, are not adsorbed to membranes. A procedure is recommended by which...
185.
Apparent In Vivo Pathway of Granulosis Virus Invasion and Infection
- Summers, Max D.
The invasion and ensuing replication of an insect granulosis virus in Trichoplusia ni is described.
186.
Radiobiological Inactivation of Epstein-Barr Virus
- Henderson, Earl; Heston, Lee; Grogan, Elizabeth; Miller, George
Lymphocyte transforming properties of B95-8 strain Epstein-Barr virus (EBV) are very sensitive to inactivation by either UV or X irradiation. No dose of irradiation increases the transforming capacity of EBV. The X-ray dose needed for inactivation of EBV transformation (dose that results in 37% survival, 60,000 rads) is similar to the dose required for inactivation of plaque formation by herpes simplex virus type 1 (Fischer strain). Although herpes simplex virus is more sensitive than EBV to UV irradiation, this difference is most likely due to differences in the kinetics or mechanisms of repair of UV damage to the two viruses....
187.
Radiobiological Inactivation of Epstein-Barr Virus
- Henderson, Earl; Heston, Lee; Grogan, Elizabeth; Miller, George
Lymphocyte transforming properties of B95-8 strain Epstein-Barr virus (EBV) are very sensitive to inactivation by either UV or X irradiation. No dose of irradiation increases the transforming capacity of EBV. The X-ray dose needed for inactivation of EBV transformation (dose that results in 37% survival, 60,000 rads) is similar to the dose required for inactivation of plaque formation by herpes simplex virus type 1 (Fischer strain). Although herpes simplex virus is more sensitive than EBV to UV irradiation, this difference is most likely due to differences in the kinetics or mechanisms of repair of UV damage to the two viruses....
188.
Theta Particles: a Structure Found in Hamster Sarcoma Virus
- Albino, Anthony P.; deHarven, Etienne; Sanders, F. Kingsley
Hamster sarcoma virus (HaSV), a ribonucleic acid tumor virus, pelleted from tissue culture fluid manifests type C morphology by electron microscopy. However, if virus is first concentrated by polyethylene glycol or ammonium sulfate followed by density gradient banding, the virus shows a dramatically atypical barred core structure, termed theta particles. This structure suggests a condensation of the ribonucleoprotein into a flat disc. Atypical particles are found with HaSV and not in similarly treated feline leukemia virus or Rauscher-murine leukemia virus. Differences in the composition of HaSV as compared with these other viruses may be responsible for the production of such...
189.
Theta Particles: a Structure Found in Hamster Sarcoma Virus
- Albino, Anthony P.; deHarven, Etienne; Sanders, F. Kingsley
Hamster sarcoma virus (HaSV), a ribonucleic acid tumor virus, pelleted from tissue culture fluid manifests type C morphology by electron microscopy. However, if virus is first concentrated by polyethylene glycol or ammonium sulfate followed by density gradient banding, the virus shows a dramatically atypical barred core structure, termed theta particles. This structure suggests a condensation of the ribonucleoprotein into a flat disc. Atypical particles are found with HaSV and not in similarly treated feline leukemia virus or Rauscher-murine leukemia virus. Differences in the composition of HaSV as compared with these other viruses may be responsible for the production of such...
190.
Molecular epidemiology of dengue viruses in Brazil
- Nogueira,Rita Maria Ribeiro; Miagostovich,Marize Pereira; Schatzmayr,Hermann Gonçalves
Dengue viruses (DEN) are found as four antigenically distinct serotypes designated DEN-1, 2, 3, and 4. Laboratory evidence that strain-intratypical variation occurs among DEN viruses has been demonstrated since the 1970s, although only with the advances in molecular technologies has it been possible to determine the genetic variability of each serotype. Genotypical identification has proven to be a useful tool for determining the origin and spread of epidemics and to correlate virulence of strains. In this report we present the results of molecular epidemiological studies with the DEN-1 and DEN-2 viruses that caused dengue epidemics in Brazil during the last...
191.
Structural Proteins of Simian Virus 40: Phosphoproteins
- Tan, K. B.; Sokol, F.
All five structural polypeptides of infectious simian virus 40 grown in African green monkey kidney cells were found to be phosphorylated. The polypeptides with the largest and smallest molecular weights are phosphorylated to a somewhat lower extent than the other polypeptides. The protein moiety of empty virus, which is essentially devoid of deoxyribonucleic acid, exhibited a degree of phosphorylation similar to that of infectious virus. In the major polypeptide (molecular weight: 49,000), the phosphate appears to be bound to the seryl or threonyl residues, or both. The nature of the phosphate-polypeptide bond in the other viral polypeptides remains obscure.
192.
Biosynthesis of the Sindbis Virus Carbohydrates
- Sefton, Bartholomew M.; Burge, Boyce W.
The sequence in which sugars are added to the Sindbis virus glycoproteins was studied. Infected cells contain three glycosylated virus-specific proteins: the two virion glycoproteins and the immediate precursor to the smaller virion glycoprotein. Larger Sindbis-specific proteins are not glycosylated. The cell-associated forms of both of the virion glycoproteins contain glucosamine, mannose, galactose, and fucose. The glycosylated precursor contains only glucosamine, mannose, and some galactose. The conversion of precursor to virion protein involves both the addition of galactose and fucose and the loss of mannose. The apparent extent of glycosylation of each virus-specific protein is not influenced by the host...
193.
Morphogenesis of Venezuelan Equine Encephalomyelitis Virus
- Bykovsky, A. F.; Yershov, F. I.; Zhdanov, V. M.
Morphogenesis of Venezuelan equine encephalomyelitis virus was studied by means of electron microscopy. Virus-specific structures (factories, viroplasts) were found at early stages of infection; these structures were composed of fibrillar and cylindrical formations, aggregates of ribosomes, and viral nucleoids. The latter emerged from fibrillar and cylindrical structures. Aggregates of viral nucleoids were found in the cytoplasm and occasionally in the nuclei of virus-infected cells. Viral envelopes and mature virions were formed on the cell membranes and on the membranes of intracellular vacuoles. Anomalous forms of virions (both polygenomic and oligogenomic) were observed.
194.
Electron Microscopy of Equine Infectious Anemia Virus
- Tajima, Masanori; Nakajima, Hideo; Ito, Yasuichiro
Equine infectious anemia (EIA) virus was observed in thin sections of infected cultured horse leukocytes by electron microscopy. The virus particles had a spherical shape and were between 80 and 120 nm in diameter. Most of them contained an electron-dense nucleoid 40 to 60 nm in diameter. They were observed to form by a process of budding from the plasma membrane and appeared to have thin surface projections. The particles described were not detected in uninfected cultured cells, and their appearance could be prevented by adding EIA immune serum to the inoculum. The implications of these findings in the classification...
195.
Structural Proteins of Simian Virus 40: Phosphoproteins
- Tan, K. B.; Sokol, F.
All five structural polypeptides of infectious simian virus 40 grown in African green monkey kidney cells were found to be phosphorylated. The polypeptides with the largest and smallest molecular weights are phosphorylated to a somewhat lower extent than the other polypeptides. The protein moiety of empty virus, which is essentially devoid of deoxyribonucleic acid, exhibited a degree of phosphorylation similar to that of infectious virus. In the major polypeptide (molecular weight: 49,000), the phosphate appears to be bound to the seryl or threonyl residues, or both. The nature of the phosphate-polypeptide bond in the other viral polypeptides remains obscure.
196.
Biosynthesis of the Sindbis Virus Carbohydrates
- Sefton, Bartholomew M.; Burge, Boyce W.
The sequence in which sugars are added to the Sindbis virus glycoproteins was studied. Infected cells contain three glycosylated virus-specific proteins: the two virion glycoproteins and the immediate precursor to the smaller virion glycoprotein. Larger Sindbis-specific proteins are not glycosylated. The cell-associated forms of both of the virion glycoproteins contain glucosamine, mannose, galactose, and fucose. The glycosylated precursor contains only glucosamine, mannose, and some galactose. The conversion of precursor to virion protein involves both the addition of galactose and fucose and the loss of mannose. The apparent extent of glycosylation of each virus-specific protein is not influenced by the host...
197.
Morphogenesis of Venezuelan Equine Encephalomyelitis Virus
- Bykovsky, A. F.; Yershov, F. I.; Zhdanov, V. M.
Morphogenesis of Venezuelan equine encephalomyelitis virus was studied by means of electron microscopy. Virus-specific structures (factories, viroplasts) were found at early stages of infection; these structures were composed of fibrillar and cylindrical formations, aggregates of ribosomes, and viral nucleoids. The latter emerged from fibrillar and cylindrical structures. Aggregates of viral nucleoids were found in the cytoplasm and occasionally in the nuclei of virus-infected cells. Viral envelopes and mature virions were formed on the cell membranes and on the membranes of intracellular vacuoles. Anomalous forms of virions (both polygenomic and oligogenomic) were observed.
198.
Electron Microscopy of Equine Infectious Anemia Virus
- Tajima, Masanori; Nakajima, Hideo; Ito, Yasuichiro
Equine infectious anemia (EIA) virus was observed in thin sections of infected cultured horse leukocytes by electron microscopy. The virus particles had a spherical shape and were between 80 and 120 nm in diameter. Most of them contained an electron-dense nucleoid 40 to 60 nm in diameter. They were observed to form by a process of budding from the plasma membrane and appeared to have thin surface projections. The particles described were not detected in uninfected cultured cells, and their appearance could be prevented by adding EIA immune serum to the inoculum. The implications of these findings in the classification...
199.
Characterization of Virus-Specific RNAs from Subacute Sclerosing Panencephalitis Virus-Infected CV-1 Cells
- Yeh, Jen
CV-1 cells infected with subacute sclerosing panencephalitis (SSPE) virus incorporated uridine-3H into at least four virus-specific RNA components in the presence of actinomycin D. The component sedimenting fastest had a sedimentation coefficient of 50s corresponding to a molecular weight of 6 × 106. The other three RNA components have sedimentation constants of 35s, 22s, and 18s corresponding to molecular weights of 2.5 × 106, 1.0 × 106, and 0.75 × 106, respectively. The base composition of the 50s RNA is distinct from that of cellular RNA and comparable with base compositions of viral RNAs of other paramyxoviruses. The base composition...
200.
Characterization of Virus-Specific RNAs from Subacute Sclerosing Panencephalitis Virus-Infected CV-1 Cells
- Yeh, Jen
CV-1 cells infected with subacute sclerosing panencephalitis (SSPE) virus incorporated uridine-3H into at least four virus-specific RNA components in the presence of actinomycin D. The component sedimenting fastest had a sedimentation coefficient of 50s corresponding to a molecular weight of 6 × 106. The other three RNA components have sedimentation constants of 35s, 22s, and 18s corresponding to molecular weights of 2.5 × 106, 1.0 × 106, and 0.75 × 106, respectively. The base composition of the 50s RNA is distinct from that of cellular RNA and comparable with base compositions of viral RNAs of other paramyxoviruses. The base composition...
