- Volume 63, Issue 1, 1982
Volume 63, Issue 1, 1982
- Animal
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Characterization of a Large Genomic Size Moloney Murine Sarcoma Virus Produced by a Transformed Rat Cell Line
More LessSUMMARYA rat cell line (78A1) transformed by the Moloney murine sarcoma virus-Moloney murine leukaemia virus (Mo-MuSV-MuLV) complex was found to produce a sarcoma virus different from the isolates previously described. Analysis of intracellular RNA of the 78A1 cell line by electrophoresis on agarose gel, and hybridization with DNA probes specific to Ml-Mo-MuSV and v-mosMo sequences revealed a size of 6.7 kilo-bases (kb) for the RNA of this sarcoma virus. This genome is larger than those of m1, m3, HT1 and 124 isolates and slightly smaller than the myeloproliferative sarcoma virus genome (7.0 kb).
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Restricted Translation of the Genome of the Flavivirus Kunjin in vitro
More LessSUMMARYVirion RNA of Kunjin virus was translated in rabbit reticulocyte lysates at a rate (7000 daltons/min) approaching that observed previously in vivo. As many as 18 polypeptides were translated and shown by tryptic peptide mapping to be closely related to one another and to contain some of the elements of envelope (E) and most of the elements of core (C) proteins of Kunjin virus. None of the products resolved in gels were precipitated by antiserum to purified E protein, but the larger products were precipitated by an antiserum against all the Kunjin virus-specified proteins. No evidence was obtained of translation of the non-structural proteins, despite attempts to retain or perturb the structure of the virion RNA. As many as 50% of the amino acid sequences in the peptide maps were not identifiable.
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Relationship between Glycoproteins of the Viral Envelope of Bunyaviruses and Antibody-dependent Plaque Enhancement
More LessSUMMARYHamster antisera against three parental bunyaviruses, Batai, Bunyamwera and Maguari viruses, and six recombinant viruses which carried the nucleocapsid protein of one parent and the glycoproteins of the other, have been tested for their interaction with each of the nine viruses under study by two assays, plaque reduction neutralization and antibody-dependent plaque enhancement. Neutralization was clearly related to the specificity of the parental glycoproteins rather than the nucleoprotein, but the antibody-dependent plaque enhancement assay showed greater cross-reactivity.
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Development of an Enzyme-linked Immunosorbent Assay for the Identification of Arthropod-borne Togavirus Antibodies
More LessSUMMARYThe applicability of the standard enzyme-linked immunosorbent assay (ELISA) for the identification of togavirus infections was investigated. Optimal concentration of gradient-purified antigen was 2.5 µg/well for alphaviruses or flaviviruses when coating polystyrene microtitre plates. A procedure for producing antigen in suckling mouse brain was developed. Results obtained with ELISA could be correlated with standard serology, but in general the ELISA was more sensitive. The ELISA was specific in differentiating alphavirus antigens. Flavivirus cross-reactivity was magnified by ELISA. ELISA should be useful as a rapid screening assay for non-related antigens, avoiding the extensive techniques currently used in standard serodiagnosis.
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Bovine Enteric Coronavirus Structure as Studied by a Freeze-drying Technique
More LessSUMMARYA strain of bovine coronavirus (FI5) was studied by electron microscopy using a freeze-drying technique. Purified coronavirus preparations show three different categories of image : (i) ‘blackberry-like’ virions, (ii) virions with a smooth depression at their surface, and (iii) apparently broken particles showing very clearly the areas of spike insertion in the virus membrane. Virus projections resemble ‘mushrooms’ with the ‘stalk’ inserted at the virus membrane. A model of the virion structure is proposed.
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Synthesis of a Unique Polypeptide in Measles Virus-infected BGM Cells
More LessSUMMARYIn measles virus-infected BGM (African green monkey kidney) cells, a unique polypeptide (84K) was identified. This polypeptide was not found in other cell lines examined and could be immunoprecipitated with anti-NP monoclonal antibody. Peptide mapping studies confirmed that it contained all the peptides of the 60K NP plus several additional ones. Pulse-chase experiments failed to establish it as a precursor of the 60K polypeptide. The possible origin of this protein is discussed.
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Ultraviolet Irradiation of Murine Cytomegalovirus
More LessSUMMARYUltraviolet irradiation of murine cytomegalovirus (MCMV) caused a rapid dose-related decline in virus infectivity, manifested by virus antigen induction, and in virus production as measured by plaque formation and infectious centre assay. The virus survival curve was multi-component, suggesting host cell-assisted reactivation. Multiplicity reactivation and photo reactivation of MCMV were not observed in these experiments. Productive infection was more sensitive to u.v. irradiation than was virus antigen production, indicating differential inactivation of virus functions. The effects of u.v. irradiation were similar in most respects to those reported for human cytomegalovirus.
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Characterization of the Different Electrophoretic Forms of the Cadang-Cadang Viroid
More LessSUMMARYThe relationship between symptom development and changes in the fast and slow electrophoretic forms of the two cadang-cadang disease-associated RNAs (ccRNA-1 and ccRNA-2) has been examined. The fast form of each is present in trees for up to 2 years before the appearance of symptoms, indicating an incubation period of about 2 years. Trees showing the first symptoms (on the nuts) contain only the fast form of the ccRNAs; the development of leaf symptoms coincides with the first detection of the slow form. After this time, both slow and fast forms are found in the newly developing fronds for the next 9 to 12 months but then, as symptoms develop, new fronds contain only the slow form. Therefore, at later stages of disease, only the slow form can be detected in all fronds. The fast form of ccRNA-1 and/or ccRNA-2 therefore appears to be the infectious form in nature. The number of nucleotides in the four ccRNAs as determined by polyacrylamide gel electrophoresis under denaturing conditions are: ccRNA-1 fast, 250; ccRNA-1 slow, 300; ccRNA-2 fast, 500; ccRNA-2 slow, 600. On the basis of two-dimensional fingerprints of ribonuclease A and T1 digests of the four ccRNAs, it was concluded that the ccRNAs are composed of repeated sequences of ccRNA-1 fast, and each of the ccRNA-2 forms is a dimer of the respective ccRNA-1 form.
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Complementation and Interference of Ultraviolet-induced Mts Mutants of Alfalfa Mosaic Virus
More LessSUMMARYTen new thermosensitive (ts) mutants of alfalfa mosaic virus (AMV), a plant virus with a tripartite genome, are described. Stable ts mutants were induced by u.v. irradiation of purified middle (M) component. Mutants were isolated by subculturing in bean plants (instead of in the usual plant host, tobacco), in which unstable ts mutants apparently arise spontaneously. As well as ts mutants, we found a mutant which in contrast to the parent strain (AMV 425) was able to infect bean plants systemically. As expected, all stable mutations mapped on M component. Complementation analysis confirmed the presence of two complementation groups on M component. This complementation is probably intracistronic. Furthermore, we found that mutants belonging to the same complementation group often interfered with the multiplication of each other, even at the permissive temperature. Taken together, these results could suggest that the product directed by AMV RNA 2 (the RNA inside M component) has two functional domains and is active in a multimeric form.
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Micromonas pusilla Virus: the Virus Growth Cycle and Associated Physiological Events Within the Host Cells; Host Range Mutation
More LessSUMMARYThe photosynthetic marine flagellate Micromonas pusilla (Butch.) Manton et Parke (Prasinophyceae) and its cytoplasmic virus, M. pusilla virus (MPV), were cloned. Host cells were maintained in liquid culture. Infectivity titration was by endpoint dilution, using loss of host chlorophyll as an indicator of the presence of infective virus. The virus growth cycle was characterized by an eclipse period of 3 h, a latent period of 7 h and a total lytic cycle of 14 h. The average burst size was 72 infective particles per cell. Inhibition of CO2 photoassimilation began 2 h after inoculation with virus. An almost immediate decrease in in vivo chlorophyll a fluorescence in infected cells was light-dependent. M. pusilla cells can mutate to virus resistance at the cell surface. Host range mutants of MPV exhibited variable infectivity in different strains of M. pusilla.
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