- Volume 66, Issue 12, 1985
Volume 66, Issue 12, 1985
- Bacterial
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Characterization of Streptococcal Bacteriophage c6A
More LessSUMMARYBacteriophage c6A is a lytic phage that infects strains of Streptococcus lactis. Infection of S. lactis C6 under standard conditions yielded 124 ± 8 p.f.u. per infected cell after a latent period of 25 min at 30 °C. The virion of c6A was shown to contain at least 12 polypeptides and a 21.9 kilobase double-stranded, linear DNA genome with complementary 5′-protruding single-stranded termini. The (G + C) content of this DNA was estimated to be 36.7%. A restriction map was constructed which indicates that a number of restriction endonucleases did not digest the DNA and that others cleaved with a much lower frequency than expected.
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- Animal
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Agent Replication Dynamics in a Long Incubation Period Model of Mouse Scrapie
More LessSUMMARYThe dynamics of scrapie agent replication in brain and spleen following intracerebral or intraperitoneal infection were investigated in a model with particularly long incubation periods [IM mice (Sinc p7) infected with 87V scrapie]. In contrast to other mouse scrapie models previously investigated, there was no delay in onset of replication (‘zero phase’) in spleen using either route of infection, For both routes infectivity levels reached a plateau in spleen, which was maintained for at least 250 days in intraperitoneally infected mice. An infectivity plateau was also apparent in brain following intracerebral infection, suggesting that there may be constraints on agent replication in brain during the later part of the incubation period. In addition, the efficiency of the intraperitoneal route to produce disease was found to be particularly low for this model.
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Neutralization of Yellow Fever Virus Studied Using Monoclonal and Polyclonal Antibodies
More LessSUMMARYMonoclonal and polyclonal antibodies with known specificity for either the 54K envelope glycoprotein or the 48K non-structural glycoprotein of yellow fever (YF) virus-infected cells were studied in plaque reduction neutralization tests. Viruses employed in the tests comprised wild-type and vaccine strains of YF and a selection of other flaviviruses. Of 17 monoclonal antibodies examined, six of the 54K-specific antibodies neutralized at least one YF preparation. Both vaccine and wild-type YF viruses varied in their susceptibility to neutralization and there were also differences between individual 17D vaccine strains. The monoclonal antibodies produced a range of titres with the different viruses, the most potent, 864, leaving no non-neutralizable fraction. Addition of anti-globulin, complement or other antibodies did not affect the results. YF-neutralizing antibodies which bound to other flaviviruses did not necessarily neutralize them; hence, neutralization could be defined as either homotypic, heterotypic or both homotypic and heterotypic. A polyclonal antiserum and a broadly reacting monoclonal antibody produced almost identical neutralization results in tests with wild-type YF viruses. In contrast, the polyclonal antiserum produced higher titres with vaccine strains of YF. In mouse passive protection experiments on the other hand, the monoclonal antibody did not differentiate between these viruses.
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Cytotoxic Lymphocytes in the Lungs of Mice Infected with Respiratory Syncytial Virus
More LessSUMMARYMice infected with respiratory syncytial virus (RSV) developed cytotoxic lymphocytes in the lungs, which lysed RSV-infected, but not uninfected cells. Cytotoxic activity was greatest 7 to 9 days after infection, was virus-specific, MHC-restricted and abolished by treatment of lymphocytes with anti-Thy 1.2 or with anti-Lyt 2.2 sera and complement. There was a close temporal relationship between the appearance of these cytotoxic lymphocytes in the lung and clearance of virus. In contrast, RSV persisted in the lungs of athymic (nude) mice and such animals failed to develop RSV-specific cytotoxic lymphocytes. Thus, cytotoxic T-cells may have an important role in recovery from RSV infection.
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Delta-9-Tetrahydrocannabinol Decreases Host Resistance to Herpes Simplex Virus Type 2 Vaginal Infection in the B6C3F1 Mouse
More LessSUMMARYThe effect of delta-9-tetrahydrocannabinol (Delta-9-THC) on host resistance to herpes simplex virus type 2 (HSV-2) vaginal infection in the B6C3F1 mouse was determined. Animals were given Delta-9-THC or vehicle on days -1 to 2, or cyclophosphamide on day -1 or on days -1 to 2. HSV-2 was introduced intravaginally on day 0. Host resistance to virus infection was assessed by comparing frequency and severity of lesions, virus shedding and mortalities. Replicate groups of animals were bled on days 5, 8, 10, 14 and 21 post-viral inoculation to allow for screening for viraemia and for definition of the effect of Delta-9-THC on the humoral response. Animals were also employed for determination of delayed hypersensitivity responses (DHR). Virus-infected animals treated with 100 mg/kg Delta-9-THC exhibited greater severity of herpes genitalis, higher mortalities and higher mean titres of virus shed from the vagina. Suppression of the humoral response to HSV-2 occurred in animals treated with this dose of drug when compared to virus-infected vehicle controls. A delay in the onset of the DHR to HSV-2 was observed in animals receiving 100 mg/kg Delta-9-THC when compared with those receiving vehicle. These results indicate that Delta-9-THC decreases host resistance to HSV-2 vaginal infection in the B6C3F1 mouse. This decreased resistance is associated with suppression of the immune response to primary infection with HSV-2.
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The Cytotoxic Response to Murine Cytomegalovirus. III. Lymphokine Release and Cytotoxicity Are Dependent upon Phenotypically Similar Immune Cell Populations
More LessSUMMARYMurine cytomegalovirus (MCMV)-immune lymph node (LN) cells were generated following 4 days culture of draining popliteal LN cells removed after bilateral hind footpad inoculation of mice with 4 × 102 p.f.u. MCMV. This cell population expressed both cytotoxic activity against MCMV-infected mouse embryo fibroblasts (MEF) and the capacity to release lymphokine upon stimulation with MCMV-infected MEF. Cytotoxicity and lymphokine release were Class I, H-2-restricted, virus-specific and dependent upon Thy1.2+, Lyt2+ cells. Mixing of 5 × 105 MCMV-immune T cells with an excess of syngeneic MCMV-infected MEF stimulators produced detectable levels of the lymphokine interleukin-3 by 1 h, with a maximum rate of its release between 1 and 6 h and plateau levels by 14 h. The capacity to stimulate virus-specific MCMV-immune T cells was acquired by MEF at 1 h after MCMV infection with maximum stimulator ability attained by 8 h. In the presence of a fixed number of MCMV-immune T cells, and titration to excess of syngeneic 3 h or 18 h MCMV-infected MEF, lower interleukin-3 plateau levels were obtained with 3 h than with 18 h MCMV-infected stimulators. This suggested that fewer T cells responded to 3 h than to 18 h MCMV-infected MEF.
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Production of a Monoclonal Antibody against an Epitope on HeLa Cells that Is the Functional Poliovirus Binding Site
P. Nobis, R. Zibirre, G. Meyer, J. Kühne, G. Warnecke and G. KochSUMMARYCell lines of primate origin carry receptors on their plasma membrane which are responsible for the specific binding of poliovirus. This paper describes the isolation and characterization of a monoclonal antibody reacting with the plasma membrane of HeLa cells. The antibody (D171) was selected for its protection of HeLa cells against the cytopathic effect of poliovirus type 1. This protection was found to extend to all three viral serotypes, while the replication of five other viruses in HeLa cells was not affected. The 125I-labelled purified antibody did not react with cell lines derived from pig, dog or rodents but bound specifically to all lines of human or primate origin. Immunoglobulin or Fab fragments of D171 prevented the binding of 35S-labelled poliovirus to HeLa cells. Conversely, nearly all binding sites of 125I-labelled D171 immunoglobulins or Fab fragments could be blocked after preincubation of HeLa cells with poliovirus. These results indicate that D171 recognizes the poliovirus receptor site on different susceptible cells and that practically all D171 binding sites are involved in the specific attachment of poliovirus to the plasma membrane. To determine whether the epitope recognized by D171 could be separated from the receptor for poliovirus, human-mouse cell hybrids were prepared and analysed. In all 40 clones tested, the susceptibility to poliovirus correlated with the binding of D171.
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Two Initiation Sites for Foot-and-Mouth Disease Virus Polyprotein in vivo
More LessSUMMARYTypically, the translation of eukaryotic mRNAs into protein is initiated at a single site. However, we have recently shown that not one but two primary products, P20a and P16, are translated from the 5′ end of the coding region of the genome of foot-and-mouth disease virus (FMDV). In this paper we show by partial protease digestion of these proteins that they differ only at their N termini, thus confirming the presence of two initiation sites for translation of FMDV RNA. Sequence analysis of two subtypes of the virus (A10 and A12) confirms the presence of two initiator AUG codons in the expected position on the genome. By correlation with protein synthesis data from these subtypes it appears that the relative use of each initiation site is dependent on its surrounding nucleotide sequence. In addition, the ratio of the two proteins when synthesized in vitro differs markedly from that when they are synthesized in vivo, suggesting the presence of a control mechanism for synthesis of P20a in vivo which may be absent in vitro. We also show that the cleavage site between these two proteins and the structural protein precursor, P88, is located closer to the N terminus of the polyprotein than has previously been reported.
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Oligonucleotide Fingerprint Analysis of Coxsackievirus A10 Isolated in Japan
More LessSUMMARYEight coxsackievirus A10 strains isolated in 1978 and in 1981 and 1982 from patients with hand, foot-and-mouth disease and with herpangina at a dispensary in Matsue city were compared by RNA fingerprinting techniques. The oligonucleotide maps of the four 1978 isolates were related to each other by 85 to 93% with respect to their large T1 oligonucleotides. In contrast, the oligonucleotide maps of the four 1981 and 1982 isolates were very different from each other. Co-electrophoresis experiments revealed that the 1981 and 1982 strains shared only 17 to 34% of their large oligonucleotides. In addition, some large oligonucleotides were found in most of the fingerprint maps of isolates from 1978 to 1982, suggesting that there are regions in the genome of coxsackievirus A10 which are not subject to mutational changes.
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On the Structure of the Acyl Linkage and the Function of Fatty Acyl Chains in the Influenza Virus Haemagglutinin and the Glycoproteins of Semliki Forest Virus
More LessSUMMARYThe acylation of the haemagglutinin (HA) of different influenza viruses and of the envelope glycoproteins of Semliki Forest virus (SFV) were analysed. The fatty acid linkage in these acylproteins was found to be resistant to a variety of organic solvents and combinations of these, even after pretreatment with various detergents. Fatty acids are released from influenza virus HA at a pH value between 11.8 and 12.1 at room temperature. Although this mild alkaline cleavage occurs rapidly, the release of fatty acids by treatment with hydroxylamine is time-, temperature- and concentration-dependent. By comparison with model esters the linkage in HA is suggested to be of the oxygenester type rather than a thioester linkage. To assay for possible functions of protein-bound fatty acids the biological activities of influenza virus (A/FPV/Rostock/34) and its solubilized spike glycoproteins were measured after deacylation. While viral haemagglutination activity was not hampered at all, its ability to haemolyse erythrocytes and infectivity were drastically reduced. Likewise, viral spike glycoproteins solubilized with detergents failed to induce haemolysis at low pH when fatty acids had been cleaved off. These results indicate the possible involvement of protein-bound fatty acids in fusion inducation through the acylated fusogenic spike glycoproteins.
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A Physical Map of the Oryctes Baculovirus Genome
More LessSUMMARYThe restriction endonucleases, BamHI, EcoRI, HindIII and PstI, cleave Oryctes baculovirus (strain PV505) DNA into 21, 43, 23 and seven fragments respectively. A large number of these fragments were cloned into the bacterial plasmids pUC8 and pBR328. These clones encompass 96% of the genome. The restriction sites for the four endonucleases were mapped using double and partial digestions of cloned fragments as well as hybridization of labelled fragments to Southern transfers of cleaved DNA. When HindIII fragment D and BamHI fragment D were hybridized to Southern transfers six regions containing reiterated sequences were found. The physical map for Oryctes baculovirus could not be orientated with respect to other published baculovirus maps because the BamHI fragment F of Autographa californica nuclear polyhedrosis virus which contains conserved polyhedrin gene sequences common to occluded baculoviruses did not bind to Oryctes baculovirus DNA.
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Intermolecular Recombination of the Herpes Simplex Virus Type 1 Genome Analysed Using Two Strains Differing in Restriction Enzyme Cleavage Sites
More LessSUMMARYIntermolecular recombination of herpes simplex virus type 1 (HSV-1) was studied by analysing the segregation of strain-specific restriction enzyme cleavage sites among progeny viruses produced after co-infection by two HSV-1 strains differing in eight restriction enzyme cleavage sites. Out of 93 progeny viruses examined, 51 clones were recombinant, and crossover sites of the recombinants were mapped on the HSV-1 genome. These sites were distributed evenly in the unique sequence of the L component (UL) and the recombination frequency in UL was estimated to be 1.12 per genome length, or 0.007 per kilobase pair. No evidence was obtained to support the existence of enhanced intermolecular recombination events in the regions containing inverted repeats and the L-S junction in comparison with the recombination frequency in UL. The finding of recombinants in an arrangement that minimized the number of crossover events suggested the participation of both of two arrangements of the L component of parental DNA (P or IS, and IL or ISL) in the generation of the recombinants. The possibility of a preference for P or IS over IL or ISL arrangements remains to be determined.
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The Structure of Adenovirus Chromatin in Infected Cells
More LessSUMMARYThe structure of adenovirus chromatin in infected cells was studied by micrococcal nuclease digestion and hybridization with virus-specific probes. In the early phase of infection (5 h) a significant proportion of viral molecules was organized like actively transcribed cellular chromatin. As expected for a transcriptionally active population of molecules, even at high multiplicity of infection the nucleosomal repeating pattern was less distinct than in a transformed cell which contained the corresponding but less active genomic region. The observed repeating pattern in infected cells was unlikely to be due to integrated molecules since less than 0.07% of input genomes became associated with cellular DNA. After the onset of viral DNA replication, the pool of viral chromatin organized like cellular chromatin rapidly increased. In addition, newly replicated molecules also maintained the cellular chromatin-like organization as measured by [3H]thymidine incorporation after the cessation of cellular DNA synthesis. These data suggest that newly replicated viral molecules are organized by histones into cell-like chromatin throughout the infection cycle. Coincident with the peak of viral DNA and core protein synthesis, and the decline of histone synthesis, the late, core-like non-repeating viral chromatin became dominant, increasingly obscuring the underlying repeating pattern. Experiments suggest that this late chromatin is destined for encapsidation, that the early chromatin persists and that viral core proteins do not displace histones on viral DNA. A model is proposed suggesting that transcription and type I replication occur on histone-condensed templates, while type II replication products late in infection are condensed by core proteins and are destined for encapsidation.
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A Proposal for Naming Adenovirus Genome Types, Exemplified by Adenovirus Type 6
Th. Adrian, B. Best and R. WigandSUMMARYA numerical code to denominate adenovirus (AV) genome types is proposed. Seven restriction endonuclease patterns are listed in alphabetical order (BamHI, BglII, BstEII, EcoRI, HindIII, KpnI, SmaI); patterns deviating from those of the prototype (1) are named 2, 3 etc. depending on the chronological order of the respective isolates. Thus AV6/3: 1231121 is a type 6 strain deviating from the prototype in three patterns, i.e. those of BglII, BstEII and KpnI. From 24 AV6 isolates, six were identical with the prototype, whereas the other strains represented 13 different genome types.
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Antibody to the 32K Structural Protein of Infectious Bursal Disease Virus Neutralizes Viral Infectivity in vitro and Confers Protection on Young Chickens
More LessSUMMARYChicken sera containing IgG antibodies specific for the 32000 (32K) mol. wt. structural polypeptide of infectious bursal disease (IBD) virus, as assessed by Western blotting, neutralized the in vitro infectivity of tissue culture-adapted IBD virus. When injected into young chickens, the serum passively protected them from challenge with pathogenic IBD virus. Chickens immunized with the 32K structural polypeptide of IBD virus, prepared by electroelution from SDS-PAGE gels, produced antibody detectable by ELISA and the virus neutralization assay, while chickens immunized with the 37K or 41.5K viral polypeptides synthesized antibody detectable by ELISA, but only very low levels of virus-neutralizing antibody. The immunoglobulin fraction of sera obtained from chickens immunized with the 32K polypeptide, but not the 41.5K polypeptide, passively protected chickens from infection with IBD virus. It is concluded that the 32K polypeptide is a major protective immunogen of IBD virus.
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Reassortment of Human Rotaviruses Carrying Rearranged Genomes with Bovine Rotavirus
More LessSUMMARYRotaviruses isolated from chronically infected immunodeficient children were previously shown to contain RNA yielding abnormal migration profiles on gels: normal RNA segments were lost or decreased in concentration, and additional bands of dsRNA were found which were derived (rearranged) from genome segments of lower molecular weight by concatemer formation. These viruses grew very slowly during passage in secondary rhesus monkey kidney cells. Upon superinfection with the tissue culture-adapted UK Compton strain of bovine rotavirus (BRV) extensive genome reassortment occurred. Clones with the following reassorted genome patterns were isolated: (i) RNA segments 5 or 6 of BRV were replaced by the corresponding RNA segments of human rotavirus; (ii) RNA segments 9 or 11 of BRV were replaced by different rearranged bands of RNA of human rotavirus; (iii) reassortants were observed containing more than one segment/rearranged band of human rotavirus RNA in different combinations. The reassortant viruses possessed functional proteins coded for by the genome segments and/or by rearranged bands of RNA of the human rotaviruses. Rearrangement of parts of the rotavirus genome may be a mechanism of evolution of these viruses.
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Release of Progeny Virus from Cells Infected with Simian Rotavirus SA11
More LessSUMMARYAnalysis of cells infected with simian rotavirus SA11 at late times of infection indicated that the particles were associated with membranes and the cytoskeleton. Although a large amount of cellular and non-structural viral proteins were released at these times, probably by cellular lysis, only virus with an outer layer was found outside the cells, while virus without an outer layer remained associated with the cells, probably with membranes and the cytoskeleton. Inhibition of glycosylation by tunicamycin did not abolish cell lysis but inhibited the liberation of particles and the non-glycosylated precursors of the structural and non-structural viral glycoproteins. These results indicate that immature virus was tightly associated with the structural matrix of the cell.
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Rapid Inactivation of Rotaviruses by Exposure to Acid Buffer or Acidic Gastric Juice
More LessSUMMARYInactivation rates of three bovine and several primate-origin rotaviruses were determined during exposure to acid buffers at pH 2.0, pH 3.0 or pH 4.0. Each rotavirus was inactivated at pH 2.0 (the acidity most resembling the normal fasting stomach) very rapidly, with half-lives for infectivity determined to be 1 min or less. Each rotavirus was inactivated at a much slower rate at pH 3.0; inactivation at pH 4.0 was minimal. No remarkable differences in acid resistance between different rotavirus strains were detected. Although these determinations were performed at room temperature (23 °C), experiments at diverse temperatures indicated an even more rapid rate of viral inactivation by acid at normal body temperature (37 °C). Studies of rotavirus exposed to natural human gastric juice at pH 1.8 or pH 2.1 revealed a rate of virus inactivation similar to that observed with glycine buffer of identical pH.
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Isolation of Feline Rotaviruses and Their Relationship to Human and Simian Isolates by Electropherotype and Serotype
More LessSUMMARYRotaviruses were detected by electron microscopy in the faecal specimens of six clinically well cats and virus was subsequently isolated from four of them. Analysis of the RNA of the isolates showed the existence of three electrophoretic types characteristic of the ‘long’ RNA electrophoretic pattern exhibited by rotaviruses. All feline isolates were neutralized only by antiserum to SA11 rotavirus, indicating that these isolates were serotype 3 rotaviruses. Antiserum prepared against a feline strain neutralized all the feline isolates as well as SA11 but showed no neutralizing activity against human isolates of serotype 1, 2 or 4.
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Survival Characteristics of Airborne Human Coronavirus 229E
More LessSUMMARYThe survival of airborne human coronavirus 229E (HCV/229E) was studied under different conditions of temperature (20 ± 1 °C and 6 ± 1 °C) and low (30 ± 5%), medium (50 ± 5%) or high (80 ± 5%) relative humidities (RH). At 20 ± 1 °C, aerosolized HCV/229E was found to survive best at 50% RH with a half-life of 67.33 ± 8.24 h while at 30% RH the virus half-life was 26.76 ± 6.21 h. At 50% RH nearly 20% infectious virus was still detectable at 6 days. High RH at 20 ± 1 °C, on the other hand, was found to be the least favourable to the survival of aerosolized virus and under these conditions the virus half-life was only about 3 h; no virus could be detected after 24 h in aerosol. At 6 ± 1 °C, in either 50% or 30% RH conditions, the survival of HCV/229E was significantly enhanced, with the decay pattern essentially similar to that seen at 20 ± 1 °C. At low temperature and high RH (80%), however, the survival pattern was completely reversed, with the HCV/229E half-life increasing to 86.01 ± 5.28 h, nearly 30 times that found at 20 ± 1 °C and high RH. Although optimal survival at 6 °C still occurred at 50% RH, the pronounced stabilizing effect of low temperature on the survival of HCV/229E at high RH indicates that the role of the environment on the survival of viruses in air may be more complex and significant than previously thought.
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Volumes and issues
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Volume 105 (2024)
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