- Volume 68, Issue 5, 1987
Volume 68, Issue 5, 1987
- Animal
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Virulence Is not Conserved in Recombinants between Herpes Simplex Virus Types 1 and 2
More LessSUMMARY
The virulence of 31 herpes simplex virus type 1 × herpes simplex virus type 2 intertypic recombinants was determined following intraperitoneal inoculation into CBA mice. Only eight of the recombinants killed any of the mice and of these, only one recombinant was as virulent as its type 2 parent, the other seven recombinants being intermediate between their type 1 and type 2 parental viruses in virulence. These results indicate that most heterotypic combinations are attenuated independently of the virulence of the parental viruses and therefore that the virulence of HSV is controlled multigenically.
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Genomic Heterogeneity of Equine Betaherpesviruses
More LessSummaryThe genomes of 51 isolates of slowly cytopathic equine herpesviruses were examined by digestion with restriction endonucleases. Forty-seven of the isolates showed considerable fragment pattern heterogeneity although common fragments were evident, especially when any two isolates were compared or when they were digested with SalI. Fifteen of the 47 viruses, selected for their diverse fragment patterns, showed a high degree of homology in Southern blot hybridization. In contrast, four viruses, representing three epidemiologically distinct isolations, shared few, if any, comigrating fragments with the 47 equine herpesvirus 2 (EHV-2) isolates, although they shared comigrating fragments with each other. These four viruses showed reduced homology to a representative EHV-2 isolate by Southern blot hybridization under stringent conditions. Although not sharply delineated from EHV-2, these four viruses grew very slowly and had low yields in vitro, and preliminary data suggested they had a significantly smaller genome than EHV-2 (148 ± 12 kb compared to 190 kb). These four viruses may be prototypic of a novel equine betaherpesvirus.
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Varicella-Zoster Virus Specifies a Thymidylate Synthetase
More LessSUMMARYA homology search of proteins predicted from the recently reported complete DNA sequence of varicella-zoster virus (VZV) revealed that the product of gene 13 was highly homologous to eukaryotic and prokaryotic thymidylate synthetases (TSs). The VZV protein was shown to be a TS by three functional tests. Firstly, a plasmid designed to express the native protein was able to complement a strain of Escherichia coli in which the natural TS gene is deleted. Secondly, in an enzyme assay for TS, extracts of the complemented strain were capable of releasing tritiated water from 2′-deoxy[5- 3H]uridylate. Thirdly, these extracts contained a protein that bound isotopically labelled 5-fluoro-2′-deoxyuridylate, a ligand specific for the active site of TS. In addition, a novel ligand-binding protein was detected in human cells infected with VZV.
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Human Monoclonal Antibodies Neutralizing Human Cytomegalovirus
More LessSUMMARYHybridomas producing human monoclonal antibodies (MAbs) against human cytomegalovirus (CMV) were generated by fusion of human spleen cells and mouse myeloma cells. Two of the six MAbs obtained neutralized viral infectivity even at concentrations lower than 1 μg/ml. One MAb required complement for neutralization but the other did not. Both MAbs recognized viral proteins of Mr 130000 and 55000. Furthermore, these neutralizing MAbs bound to the surface membrane of CMV- infected cells. These results suggest that human MAbs may provide a new means of passive immunization against CMV infection in humans.
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Antigenic Variants of Colorado Tick Fever Virus
More LessSUMMARYTwenty strains of Colorado tick fever (CTF) virus, isolated from ticks, mammals and humans, and two antigenic relatives of CTF virus were compared in crossneutralization tests. Viruses were tested using single-inoculation sera prepared in hamsters. Antigenic variation, as measured by differences detected in the neutralization test, was noted among the virus isolates identified as strains of CTF virus. The virus strains isolated from humans appeared to vary the most in serological reactions. The two antigenic relatives of CTF virus are clearly distinct from strains of CTF and are different from each other. Antigenic relationships between these two viruses were established using two sets of single-inoculation antisera and both complement fixation and neutralization tests. Six distinct antigenic variants of CTF virus isolated from humans and the virus strain from ticks (75V1906) that showed the least antigenic variation, were tested against 49 coded serum pairs from clinically diagnosed cases of CTF. Significant differences were noted in the number of convalescent-phase sera that reacted with each virus strain and in the number of seroconversions observed with each test virus strain. Convalescent phase sera that reacted with multiple virus strains often varied significantly in antibody titre from one virus strain to another. This indicates that, in some instances, antibody was probably produced in response to infection by different antigenic variants of CTF virus.
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A Physical Map of the Pieris rapae Granulosis Virus Genome
More LessSUMMARYA physical map for the genome of Pieris rapae (imported cabbageworm) granulosis virus (PrGV) was prepared using the restriction endonucleases BamHI, EcoRI, HindIII, KpnI, SacII and SacI. The size of the genome was estimated to be 106·5 kbp. PrGV DNA sequences homologous to Trichoplusia ni GV granulin gene sequences and to some Autographa californica nuclear polyhedrosis virus EcoRI fragment sequences were located by Southern blotting. Linear organization of the two baculoviruses was compared.
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Replication of Long Virus-like Particles in the Reproductive Tract of the Ichneumonid Wasp Diadegma terebrans
More LessSummaryLong virus-like particles were found in the apical region of the calyx in the ichneumonid wasp Diadegma terebrans. Replication began in foci of intranuclear inclusion bodies where long, 20 nm diameter electron-dense cylinders were produced. These putative nucleocapsids were released into the cytoplasm after nuclear disintegration and became enveloped in areas containing many membrane-bound vesicles. Mature particles appeared in large vacuoles and were released by cell lysis into the calyx lumen. The mature particles were enveloped, 65 nm in diameter with a 20 nm diameter nucleocapsid and a length of at least 1 μm with a long, narrow (20 nm diameter) end structure. This is the first report of a virus with such a morphology replicating in the family Ichneumonidae.
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Methylation of Marek’s Disease Virus DNA in Chicken T-lymphoblastoid Cell Lines
More LessSUMMARYMethylation of Marek’s disease virus serotype 1 (MDV1) DNA in both productively and latently infected cells was examined by restriction endonuclease analyses with the isoschizomeric pair HpaI and MspI The latent MDV1 DNA in T-lymphoblastoid cell lines established from chicken T-lymphomas was considerably methylated, whereas methylation of the virus DNA sequences was not detected in productively infected cells.
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Sequence Analysis of the Matrix Protein Gene of Human Parainfluenza Virus Type 3: Extensive Sequence Homology among Paramyxoviruses
More LessSUMMARYThe sequences of the human parainfluenza virus type 3 (PIV3) matrix (M) mRNA [1150 nucleotides exclusive of poly(A)] and predicted M protein (353 amino acids) were determined by sequence analysis of cloned cDNA and viral genomic RNA. The gene- end sequence of the M gene dilfered from the semi-conserved gene-end sequence of the other PIV3 genes by an apparent insertion of eight nucleotides. The PIV3 M protein shared high sequence homology with Sendai virus and moderate homology with measles virus and canine distemper virus. Statistical analysis of the available sequences showed that the M protein was the most highly conserved parainfluenza viral protein.
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- Plant
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In vitro Translation of the Double-stranded RNA Genome from Beet Cryptic Virus 1
More LessSummaryThe double-stranded RNA genome of beet cryptic virus 1 (BCV 1) has been translated, after denaturation, in a wheat germ cell-free system. Two major polypeptides, of approximate M r 52000 and 67000, were produced. The smaller polypeptide, encoded by RNA 2 (M r 115 × 106), was immunoprecipitated by an antiserum against virus particles, and is therefore likely to be the coat protein; the larger polypeptide, encoded by RNA 1 (M r 1·36 × 106), is a likely candidate for the viral transcriptase. These two proteins represent most of the coding capacity of the BCV 1 genome (88 % for RN A 1 and 82 % for RNA 2), thus BCV 1 RNAs seem to act as monocistronic genes.
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Time-resolved Fluoroimmunoassay in the Detection of Plant Viruses
H. Siitari and A. KurppaSummaryTime-resolved fluoroimmunoassay (TR-FIA) was used to detect potato virus Y in potato leaf extracts diluted at least 106-fold, and in extracts of secondarily infected dormant tubers diluted 10- or 102-fold depending on the virus strain used. TR-FIA was also used to detect potato virus X in extracts of secondarily infected tubers diluted up to 106-fold. The response in the TR-FIA using a two-incubation method was linearly related to the virus concentration in a series of dilutions and the method can therefore be used for quantitative analysis. TR-FIA was found to be five to 100 times more sensitive than conventional double antibody sandwich ELISA.
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- Corrigendum
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