- Volume 70, Issue 11, 1989
Volume 70, Issue 11, 1989
- Review Article
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Some Highlights of Virus Research in 1988
More LessOur review of the highlights in virus research in 1988 differs from the previous highlight reviews (McGeoch et al., 1986, 1987, 1988c) in that it includes work on plant viruses as well as animal viruses. This change is an attempt to make these reviews more general and to indicate areas of similarity and contact between the viruses of different kingdoms. Nonetheless it remains a highly selective view of progress in a wide and expanding scientific field.
We start by describing the current work on three specific groups of viruses, herpesviruses, hepadnaviruses and hepatitis delta virus (HDV). This leads into a discussion of mechanisms by which viral genes are replicated and expressed and then into some recent findings on viral genome organization, virus structure, the use of transformation in the study of plant viruses, and we conclude with an account of new disease agents.
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- Animal
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The Cloning and Expression in Escherichia coli of Sequences Coding for p24, the Core Protein of Human Immunodeficiency Virus, and the Use of the Recombinant Protein in Characterizing a Panel of Monoclonal Antibodies against the Viral p24 Protein
More LessSummaryThe sequences encoding the p24 core protein of human immunodeficiency virus type 1 were identified in a cDNA library made from infected CEM cells. The nucleotide sequence of the DNA coding for p24 was shown to be very similar but not identical to the sequences of lymphadenopathy virus and human T-cell leukaemia virus type IIIb. These sequences were expressed in Escherichia coli at the amino terminus of β-galactosidase and used to screen a panel of monoclonal antibodies raised against virus-expressed p24. Regions containing the epitopes of five of the monoclonal antibodies were located using a series of amino- and carboxy-terminal deletion mutants of the recombinant p24 protein.
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The Expression in Escherichia coli of Sequences Coding for the p18 Protein of Human Immunodeficiency Virus and the Use of the Recombinant Protein in Characterizing a Panel of Monoclonal Antibodies against the Viral p18 Protein
SummaryThe sequences coding for the p18 protein of CBL-1, a British human immunodeficiency virus (HIV) type 1 isolate, were expressed in Escherichia coli as β-galactosidase fusion proteins. The recombinant proteins were used to screen a panel of five monoclonal antibodies (MAbs) raised against p18 expressed in CBL-1-infected cells. The regions containing the epitopes for four of the MAbs were located using carboxy deletion mutants and synthetic peptides. The epitope of one of the MAbs (1D9) was reconstructed as part of an unfused, E. coli-expressed p18 protein using the polymerase chain reaction technique. Four different HIV strains and one lymphadenopathy virus type 2 strain were analysed by fluorescence-activated cell sorting of live infected cells using the p18-reactive MAbs.
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Topographical and Functional Mapping of Epitopes on Hog Cholera Virus with Monoclonal Antibodies
More LessSummaryCompetitive binding studies and antigen capture assays were done with monoclonal antibodies (MAbs) raised against hog cholera virus (HCV) to map the corresponding epitopes. A model was constructed in which the 13 epitopes were situated in four distinct antigenic domains: A, B, C and D. Domain A was subdivided into A1, A2 and A3. The functional relevance of this model was assessed by the characterization of pestivirus strains, by neutralization studies with the MAbs, and by isolation of variants that escaped neutralization. The topographical arrangement of the epitopes, as constructed in the model, was corroborated by the functional assays. The MAbs that defined domains A1 and A2 recognized all 94 HCV strains tested. Domains A3, B, C and D varied among the HCV strains. Neutralization was observed with MAbs defining domains A1, B and C. Synergistic neutralization occurred using MAbs against domains A1 and B, and A1 and C, but not within the domains. With MAbs defining A1, B or C, variants could be isolated that escaped neutralization and immunostaining by these MAbs.
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Specificity of the Murine T Helper Cell Immune Response to Various Alphaviruses
More LessSummaryWe investigated the specificity of the T helper (Th) cell immune response to three alphaviruses: Venezuelan equine encephalomyelitis (VEE), eastern equine encephalitis (EEE) and western equine encephalitis (WEE). Single cell suspensions were prepared from spleens of virus-primed C3H mice, and T lymphocyte populations were enriched by nylon wool chromatography. T cells were incubated in vitro with irradiated, syngeneic splenic stimulator cells previously exposed to purified virus. Cellular proliferation was measured by [3H]thymidine uptake 5 days post-stimulation. The predominant proliferating cell type secreted interleukin-2 and was of the Th cell phenotype Thy-1+, Lyt-1+,2‒, L3T4+. Stimulation of VEE, EEE and WEE virus-primed Th cells with homologous and heterologous virus resulted primarily in a proliferative response specific for the immunizing virus. The corresponding antibody response, as measured by ELISA using purified virus as antigen, was also specific for the immunizing virus. The magnitude of the blastogenic response of VEE TC-83 virus-primed lymphocytes to a battery of VEE subtype viruses was remarkably similar to schemes of antigenic classification. The results indicate that the dominant Th cell epitopes on these alphaviruses represent regions largely virus-specific and lead to a virus-specific B cell response which does not change over time after primary inoculations of mice with VEE and WEE viruses and multiple inoculations of mice with EEE virus.
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Virulent Avian Influenza A Viruses: Their Effect on Avian Lymphocytes and Macrophages in vivo and in vitro
More LessSummaryTo investigate the pathogenesis of virulent avian influenza A viruses, the effect of A/turkey/Ont/7732/66 (H5N9) (Ty/Ont), A/tern/South Africa/1961 (H5N3) (Tern/S.A.) and A/chicken/Pennsylvania/1370/83 (H5N2) (Ck/Penn) on avian lymphoid cell populations was examined in vivo. Previous studies have shown that infection of chickens with Ty/Ont resulted in the extensive destruction of lymphoid tissues. In this study, other virulent avian H5 influenza viruses, Tern/S.A. or Ck/Penn, had little or no effect on lymphoid tissues of infected chickens. Therefore the effect of Ty/Ont on lymphoid tissue is a specific activity of this virus only and not of other virulent avian H5 influenza strains. To examine the role of viral replication in the destruction of lymphocytes, in vitro cultures of avian macrophages and lymphocytes were inoculated with Ty/Ont. Macrophages supported the synthesis of viral proteins whereas lymphocytes produced small, but detectable amounts of viral protein; however, infectious virus was not produced by either cell type. Furthermore inoculation of chicken spleen cells with Ty/Ont in vivo and in vitro had a profound effect on the proliferative response of lymphocytes to concanavalin A. These results suggest that Ty/Ont infects macrophages as well as lymphocytes in the chicken, and the effects of the virus on both cell types may well contribute to lymphoid necrosis.
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Pathogenesis of Hantaan Virus in Mice
More LessSummaryThe virulence of two virus clones (HV cl-1 and HV cl-2) of Hantaan virus, which were plaque-purified on Vero E6 cells, were compared in suckling mice infected by the intraperitoneal or intracerebral route. HV cl-1 increased the mortality of the mice whereas HV cl-2 did not. Furthermore, virus of high titre was isolated from various organs of mice infected with HV cl-1 and high titres were maintained, whereas after infection with HV cl-2, virus was isolated from various organs only in low titre and only temporarily. HV cl-1 strongly induced cell-to-cell fusion, but the cell fusion activity was at a minimum level in cells infected with HV cl-2. However these two clones induced similar titres of antibodies in mice. Cytotoxic T lymphocyte assays against macrophages infected with homologous and heterologous virus showed that cytotoxic T cell activity was induced in mice infected with HV cl-2, but suppressed in mice infected with HV cl-1. These results suggest that an alteration in the cell fusion function and the cytotoxic T cell activity are important in the pathogenesis of Hantaan virus infection in newborn mice.
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Molecular Pathogenesis of Neural Lesions Induced by Poliovirus Type 1
SummaryUsing in situ hybridization techniques for viral RNA and employing a specific riboprobe, we have detected virus in neural cells of monkeys infected with poliovirus type 1 (PV-1) by the intraspinal route. In monkeys paralysed after inoculation of a neurovirulent revertant of PV-1/Sabin strain, viral RNA was detected in motor neurons and their processes, and in polymorphonuclear and small neural cells. Quantitative in situ hybridization provided evidence of viral replication in individual cells suggesting that the death of motor neurons was due to the direct effect of poliovirus replication in these cells. The histological study of neural lesions of monkeys paralysed after infection with the attenuated Sabin strain of PV-1 revealed two major differences compared to monkeys infected with a virulent strain: (i) the number of destroyed motor neurons was reduced and limited to the site of inoculation and (ii) the inflammatory reaction was localized but more intense. An account is given of the difference in histopathology induced by virulent and attenuated strains of PV-1 in the central nervous system.
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Serological Prospects for Peptide Vaccines against Foot-and-Mouth Disease Virus
SummaryAntibodies to a synthetic peptide corresponding to the 141 to 160 amino acid sequence of the protein VP1 of type O foot-and-mouth disease virus (FMDV) neutralize a wider range of type O isolates than anti-virion serum. Extending this peptide at the amino terminus reduced the number of strains neutralized by the anti-peptide sera. Reactions with antisera to peptides representing non-contiguous native sequences showed that it was also possible to increase the number of strains effectively neutralized. Selected substitutions of a single amino acid at position 148 markedly altered the neutralizing specificity of antibodies elicited by the 141 to 160 peptide. In particular, a peptide with an L → S substitution at this position induced antibodies which neutralized a type O and a type A virus equally, and guinea-pigs inoculated with it were protected from challenge with either virus. Attempts to isolate variant viruses resistant to neutralization with anti-peptide antibody indicated that these occurred at low frequency, and there was some evidence that resistance may be partially conferred by mutations outside the peptide sequence.
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Hydrolysis of a Series of Synthetic Peptide Substrates by the Human Rhinovirus 14 3C Proteinase, Cloned and Expressed in Escherichia coli
More LessSummaryThe 3C proteins of several picornaviruses, including poliovirus, foot-and-mouth disease virus (FMDV) and encephalomyocarditis virus (EMCV), have been demonstrated to be cysteine-type proteinases, involved in the processing of the respective polyproteins expressed by the monocistronic RNA genome. Nucleotide sequencing data have indicated that the human rhinovirus 14 (HRV-14) RNA genome encodes a homologous 3C protein. The HRV-14 3C protein was purified to homogeneity from Escherichia coli expressing the cloned 3C genomic fragment. The enzyme was assayed against peptides corresponding to those residues, predicted (by nucleotide sequencing data) to occur at authentic cleavage sites within the polyprotein. The peptides representing the 1B/1C, 2A/2B, 2C/3A, 3A/3B, 3B/3C and 3C/3D cleavage sites, where proteolysis was predicted to occur at a Gln-Gly junction, were all cleaved by the 3C proteinase. The hydrolysis was shown (by reverse phase fast protein liquid chromatography and amino acid analysis) to occur specifically at the Gln-Gly bond in each of the peptides. The ready availability of such convenient substrates facilitated the further characterization of the 3C proteinase. By contrast, peptides corresponding to the predicted 2B/2C and 1C/1D cleavage sites, where the processing was presumed to occur at a Gln-Ala or Glu-Gly bond respectively, were not cleaved by the 3C proteinase. The ability of the HRV-14 3C proteinase to hydrolyse the synthetic peptides was inhibited if a Cys → Ser(146) mutation was introduced into the protein. Studies with known proteinase inhibitors substantiated the conclusion that the HRV-14 3C protein appears to be a cysteine proteinase and that the Cys residue at position 146 may be the active site nucleophile. The HRV-14 3C proteinase probably plays an important role, analogous to that implied for the poliovirus 3C proteinase, in the replication of the virus and thus represents a potential target for antiviral chemotherapy.
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The Complete Nucleotide Sequence of Coxsackievirus A21
More LessSummaryWe have determined the complete nucleotide sequence of coxsackievirus A21(CAV-21), the first member of this enterovirus subgroup to be analysed in molecular detail. The sequence, which is 7401 nucleotides long, encodes an open reading frame of 2206 codons, preceded by a 5′ non-coding region of 711 nucleotides and followed by a 3′ non-coding region of 72 nucleotides plus a poly(A) tract. The most striking feature is the remarkable homology to the poliovirus (> 90% at the amino acid level) in the 3′ part of the genome. The rest of the genome is much less homologous, suggesting that CAV-21 is a recombinant virus. Rhinovirus-like characteristics, including the length of the 5′ non-coding region and a slight --U/--A imbalance in codon usage, may be related to the fact that CAV-21, like rhinoviruses, infects the upper respiratory tract. However, the sequence sheds little light on the molecular basis of the shared receptor specificity.
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Comparison of Antigenic Sites of Subtype-specific Respiratory Syncytial Virus Attachment Proteins
SummaryA panel of 19 monoclonal antibodies (MAbs) were used to probe the antigenic relationships between the G (attachment) proteins of A and B respiratory syncytial virus (RSV) subtypes (GA and GB). At least three and two antigenic sites were present on GA and GB, respectively, including a shared neutralizing site. Most of the antibodies had some degree of complement-independent neutralizing capacity, but in common was a large neutralization-resistant fraction of virus (range 13 to 78%). Passive administration of MAbs to the cross-reactive antigenic site reduced pulmonary virus titres of both A and B subtype virus in the cotton rat model. Protection with subtype-specific MAbs, however, did not always correlate with in vitro neutralizing capacity. The cross-reactive antigenic site appears to be stable to denaturation by polyacrylamide gel electrophoresis and is present on the unglycosylated and partially glycosylated forms of GA and GB by Western blot analysis of infected cell lysates.
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Effect of Serial Passage on Genetic Homogeneity of a Plaque Variant of Lymantria dispar Nuclear Polyhedrosis Virus (Hamden LDP-67)
More LessSummaryThe wild-type Hamden gypsy moth baculovirus preparation (LDP-67) was subjected to plaque purification in IPLB-LD-652Y cells, resulting in three distinguishable classes of variants, based on the number of polyhedra produced per cell in vitro. Representatives were designated Ld-S (several polyhedra per cell), Ld-F (few polyhedra per cell) and Ld-V (variable numbers of polyhedra per cell). These representative phenotypic variants were compared to the wild-type by restriction enzyme analysis and by bioassay in Lymantria dispar larvae. With all enzymes tested the variants demonstrated restriction site polymorphism. The genome size of the three variants was estimated at 159 to 163 kb. In bioassay trials two of the variants, Ld-V and Ld-S, exhibited LD50 values approximately 3·9 times lower than the LD50 of wild-type virus. The Ld-F variant was not infective in feeding trials. The stability of Ld-S was tested by high multiplicity passage (HMP) in IPLB-LD-652Y cells. By the twentieth undiluted passage (P-20), the in vitro cytopathic effect of this variant was significantly altered. DNA isolated from the P-20 stock exhibited several differences in the restriction endonuclease profile relative to the early passage virus. Genomic alterations were more clearly visualized after plaque purification of the Ld-S (P-20) stock. Four of the five plaques chosen contained what appeared to be two distinct viral populations. One of these populations, which could be isolated by repeated plaque purification, had a restriction enzyme profile identical to the pre-HMP Ld-S variant. The second population, characterized by high M r BglII bands not present in the Ld-S profile, could never be plaque-purified of submolar amounts of the first population. The possibility that this population represents a defective interfering virus is discussed. The source of additional DNA in the P-20 variants was investigated by probing blots of these variants with labelled total cellular DNA. No specific hybridization to any of the fragments was obtained, suggesting that the P-20 variants arose by rearrangements involving solely viral DNA.
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Identification of Immunogenic Regions of the Major Coat Protein of Human Papillomavirus Type 16 that Contain Type-restricted Epitopes
SummaryWe have identified regions of the major capsid protein, L1, of the human papillomavirus (HPV) type 16 (HPV-16 L1), that are recognized by five monoclonal antibodies (MAbs) raised to a bacterial fusion protein containing residues 172 to 375 of HPV-16 L1. All five MAbs recognized HPV-16-infected tissue sections by immuno-histochemistry, but not sections infected with HPV-1a (cutaneous warts), HPV-6b or -11 (genital warts). MAbs 3D1, 5A4 and 1D6 also recognized HPV-2-infected sections (cutaneous warts); MAb 8C4 recognized only sections containing HPV-16. Four MAbs (8C4, 3D1, 1D6 and 5A4) recognized a synthetic peptide corresponding to residues 269 to 284 of HPV-16 L1; within this region a minimum antibody binding site was identified, a tripeptide 276 to 278. However the complete epitope appears to extend beyond these residues and beyond HPV-16 L1 (269 to 284). The fifth MAb, 1C6, recognized bacterial fusion proteins containing HPV-6b L1, -16 L1 or -18 L1 using immunoblots, yet appeared HPV-16-specific when tested on infected tissue sections. This MAb recognized five amino acids within a different region of HPV-16 L1 (residues 299 to 313).
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The Role of Methylation in the Phenotype-dependent Modulation of Epstein-Barr Nuclear Antigen 2 and Latent Membrane Protein Genes in Cells Latently Infected with Epstein-Barr Virus
More LessSummarySeven virus-encoded proteins are regularly expressed in Epstein-Barr virus (EBV)-transformed lymphoblastoid (LCL) cell lines: the EBV nuclear antigens EBNA 1 to 6 and the latent membrane protein (LMP). In nasopharyngeal carcinoma (NPC), only EBNA 1 is regularly expressed; LMP is detected in about 50% of the tumours. In Burkitt's lymphoma (BL) tumours, only EBNA 1 is expressed. Also, in BL-derived cell lines that maintain the phenotypic markers characteristic of the in vivo tumour (group I), only EBNA 1 is expressed. EBV was rescued by induction or cocultivation from one BL cell line with a restricted group I pattern, and from one NPC tumour, into normal B cells. In the resulting LCLs EBNA 1 to 6 and LMP were expressed. We assessed the level of methylation in the genes encoding EBNA 2 and LMP by restriction fragment analysis using the methylation-sensitive enzymes SmaI and HpaII. These genes were extensively methylated in the group I BL line Rael and the nude mouse-passaged C15 NPC tumour, but were demethylated in the derived LCLs. In the LMP expressing the NPC tumour, but were demethylated in the derived LCLs. In the LMP-expressing coding exons were methylated. The EBNA 1 coding exon was methylated in the Rael line and in NPC, in spite of expression. In contrast, CpG pairs in ori P were originally hypomethylated and remained so after their transfer to LCLs. The cell phenotype-dependent pattern of EBV gene methylation correlated with the phenotype-dependent pattern of EBNA and LMP expression. The specific patterns of methylation localized to controlling regions (ori P and 5′ flanking sequences) also suggest a specific role for methylation in the regulation of EBNA and LMP expression.
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A Comparative Analysis of the Sequence of the Thymidine Kinase Gene of a Gammaherpesvirus, Herpesvirus Saimiri
More LessSummaryWe present the nucleotide sequence of a region from the genome of the A + T-rich gammaherpesvirus, herpesvirus saimiri (HVS), which includes the coding sequences for the viral thymidine kinase (TK) gene. The organization of genes in this region resembles the homologous region of the Epstein-Barr virus (EBV) genome and is very compact, using overlapping coding sequences and with nucleotides shared by initiation and termination codons of neighbouring reading frames. The HVS TK is predicted to contain a 527 residue polypeptide with the first part of the presumptive nucleotide-binding site [(L, I, V)(F, Y)(I, L)(D, E)(G)(X)(X)(G)(L, I, V, M)(G)(K)(T, S)(T, S)] located at residues 212 to 224. This motif is close to the amino terminus of the TK polypeptides of alphaherpesviruses and the polypeptides of the cellular and poxvirus-encoded enzymes. The corresponding reading frame of the human gammaherpesvirus (EBV) also has a long amino-terminal extension but significant amino acid sequence similarities between the HVS and EBV sequences are not observed until the region of the nucleotide-binding site. Comparisons of these homologous carboxy-terminal sequences of the HVS- and EBV-encoded proteins with those from six alphaherpes viruses and proteins encoded by Marek's disease virus (MDV) and the herpesvirus of turkeys (HVT) confirm that the HVS and EBV sequences are products of a distinct lineage. The sequences of the MDV and HVT encoded enzymes are significantly more similar to sequences of alphaherpesvirus enzymes than to those of HVS and EBV. Comparison of these 10 highly divergent TK sequences extends and refines the identification of essential features of this family of herpesvirus enzymes and defines 19 positions at which all sequences have identical residues.
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Nucleotide and Predicted Amino Acid Sequences of the Marek's Disease Virus and Turkey Herpesvirus Thymidine Kinase Genes; Comparison with Thymidine Kinase Genes of Other Herpesviruses
More LessSummaryIn this paper we present the nucleotide sequences of the thymidine kinase (TK) genes of two avian herpesviruses: a highly oncogenic strain of Marek’s disease virus (MDV strain RB1B) and its serologically related vaccine virus, the herpesvirus of turkeys (HVT strain Fc-126). The predicted coding regions of the two genes are 1029 and 1050 nucleotides respectively, corresponding to polypeptides of 343 and 350 amino acids in length. Putative nucleotide- and nucleoside-binding sites have been identified within the two predicted amino acid sequences. The MDV and HVT TK amino acid sequences exhibit 58.2% amino acid identity. Comparison with other available herpesvirus TK sequences reveals a greater homology to those of the alphaherpes-viruses than to those of the gammaherpesviruses. No overall homology was found when compared with the chicken cytoplasmic TK sequence.
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Location and Characterization of the Bovine Herpesvirus Type 2 Thymidine Kinase Gene
More LessSummaryThe precise genomic location and the nucleotide sequence of the bovine herpesvirus type 2 (bovine herpes mammillitis virus) thymidine kinase (TK) gene have been determined. The genomic location of the TK gene was found to be in a similar position to that of herpes simplex virus. The coding region consists of 918 bases, which is slightly smaller in length than other reported herpesvirus TK genes. However with an M r of 38108 the individual protein is similar in size to other herpesvirus TK enzymes. Despite there being only limited overall sequence homology with the TK genes of other herpesviruses, there are several regions of extensive homology at the amino acid level.
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The Herpes Simplex Virus Type 2 (HG52) Variant JH2604 Has a 1488 bp Deletion which Eliminates Neurovirulence in Mice
More LessSummaryThe herpes simplex virus type 2 (HG52) deletion variant JH2604 is avirulent (LD50 > 107 p.f.u./mouse) for mice compared to the parental wild-type virus (LD50 < 102 p.f.u./mouse) and fails to replicate in vivo. JH2604 has a 1488 bp deletion within the 3 kb BamHI v fragment (0 to 0·02 and 0·81 to 0·83 map units) which removes one copy of the 17 bp direct repeat DR1 element of the ‘a’ sequence and terminates 522 bp upstream of the 5′ end of the immediate early gene 1. In vivo selection after transfection of intact JH2604 DNA with the BamHI g (v + u) joint fragment of HG52 results in the isolation of wild-type virus with an LD50 of < 102 p.f.u./mouse. These results show that a 1488 bp sequence within the terminal portion of the genome long repeat region confers neurovirulence on strain HG52.
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The Terminal Protein Gene 2 of Epstein-Barr Virus Is Transcribed from a Bidirectional Latent Promoter Region
More LessSummaryThe intact terminal protein genes (TP1 and TP2) of Epstein–Barr virus (EBV) are created upon infection by circularization of the linear viral genome at its terminal repeats. The structure of the 1·7 kb TP2 latent mRNA has been determined by cDNA analysis and Northern blotting, revealing its close relation to TP1 mRNA. The 1·7 kb transcript is expressed from a different promoter and has a different 5′ exon from TP1 but is also spliced across the terminal repeats. The last eight exons are common to the TP1 and TP2 RNAs. The TP2 promoter is 3·3 kb downstream of the TP1 promoter and is part of a bidirectional latent EBV promoter region transcribing the TP2 and the latent membrane protein RNAs in opposite directions.
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Identification of 21 Genes of Infectious Laryngotracheitis Virus Using Random Sequencing of Genomic DNA
More LessSummaryDNA from infectious laryngotracheitis virus (ILTV) was randomly sheared and cloned into the M13 bacteriophage. Clones containing ILTV DNA were sequenced and the predicted amino acid sequences were compared to the known sequences of other herpesviruses using computer analysis. Twenty-one ILTV genes were identified, 20 by comparison to varicella-zoster virus and 19 by comparison to herpes simplex virus type 1; only 12 genes, giving consistently lower homology scores, were found by comparison with the gammaherpesvirus Epstein-Barr virus, indicating that ILTV sequences bear greater similarity to other alpha- than to gammaherpesvirus sequences.
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Expression of the Human Parvovirus B19 Protein Fused to Protein A in Escherichia coli: Recognition By IgM and IgG Antibodies in Human Sera
More LessSummaryA 1·4 kb fragment (nucleotides 2430 to 3901) encoding portions of the human parvovirus B19 structural proteins was inserted into the pRIT2 plasmid expression vector containing the gene encoding staphylococcal Protein A under the control of the phage λ promoter PR. The fusion protein was used to raise antibodies in rabbits. The sera were shown by immune electron microscopy to agglutinate B19 particles and were also shown to recognize the VP2 B19 capsid protein, by Western blot analysis. The B19 antigenicity of the fusion protein was confirmed by immunoblot and enzyme immunoassay with IgG and IgM anti-B19-positive reference human sera.
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Human Papillomavirus Type 56: a New Virus Detected in Cervical Cancers
More LessSummaryA new human papillomavirus type (HPV-56) was identified by low stringency Southern blot analysis with an HPV-31 DNA probe, in a cervical intraepithelial neoplasm (CIN). The DNA of this virus was molecularly cloned and shown to be a new HPV type based on the absence of cross-reactivity to HPV types 1 to 55 under high-stringency hybridization conditions. At low stringency, HPV-56 was most related to HPV types 30 and 45. The deduced organization of the open reading frames of HPV-56, from hybridization and partial nucleotide sequence analyses, reveals a typical HPV genome. HPV-56 was detected in two of 464 normal cervical tissues, in five of 227 cervical condylomas and CIN, and in two of 84 invasive cancers of the cervix.
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Location of Neutralizing Epitopes on the Fusion Protein of Newcastle Disease Virus Strain Beaudette C
SummaryA panel of eight neutralizing monoclonal antibodies (MAbs) against the fusion (F) protein of Newcastle disease virus (NDV) has been shown to locate a major antigenic site on the basis of competitive binding assay and additivity index studies. Five epitopes (A1 to A5) have been located within this site on the F protein of the Beaudette C strain of NDV on the basis of cross-resistance plaque assays of MAb-resistant mutants raised against these MAbs. Epitopes A1, A4 and A5 are distinct; epitope A2 partially overlaps epitope A3. Nucleotide sequence analysis of the F genes of MAb-resistant mutants showed that each predicted single amino acid substitutions ranging from amino acid residues 157 to 171 for epitope A4 and at residues 72, 78, 79 and 343 for epitopes A1, A2, A3 and A5 respectively. These locations indicate that both the F1 and F2 fragments are involved in the formation of a single antigenic site and suggest the involvement of extensive protein folding in the active form of this F protein.
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Typing of Human Rhinoviruses Based on Sequence Variations in the 5′ Non-coding Region
More LessSummaryUnambiguous assignment of restriction enzyme patterns to six individual serotypes of human rhinovirus was accomplished after amplification of a 380 bp DNA fragment derived from the 5′ non-coding region. This was possible even though serotypes 1A and 1B and serotypes 2 and 49 differed only at 10 and 15 positions respectively. The method utilizes the conserved and variable components of this part of the genome and provides the basis for a simple and rapid method for typing of human rhinoviruses.
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Nucleotide Sequence of the Capsid Protein Gene of Barley Yellow Mosaic Virus
SummaryThe sequence of the 3′-terminal 1370 nucleotides of barley yellow mosaic virus (BaYMV) RNA 1 was determined. The sequence contains a long open reading frame (ORF) of 1137 nucleotides and a non-coding region of 231 nucleotides upstream of the poly(A) tail. Mapping of the partial amino acid sequences of the capsid protein onto the putative translational product of the ORF indicates that the 3′-proximal region of RNA 1 encodes the capsid protein which consists of 297 amino acids with an M r of 32334; the capsid protein is produced by proteolytic processing from a precursor polypeptide at a glutamine-alanine dipeptide. The removal of the N- and C-terminal regions of the capsid protein by mild proteolysis of intact virus particles indicates that both terminal regions are exposed on the external surfaces of virus particles. Alignment of the BaYMV capsid protein sequence with those of some potyviruses showed only small blocks of homology which contrast with the extensive matches among potyviruses. This fact together with the genome organization and the vector specificity clearly distinguishes BaYMV from potyviruses.
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Nucleotide Sequences of 5′ and 3′ Non-coding Regions of Pepper Mild Mottle Virus Strain S RNA
More LessSummaryThe nucleotide sequences of the 5′ and 3′ non-coding regions of pepper mild mottle virus strain S (PMMV-S) RNA were determined; they are more like corresponding sequences of tomato mosaic virus (ToMV) RNA than those of any other tobamovirus reported so far. The 5′ leader contains a 68 nucleotide guanosine-free sequence which differs in several nucleotides from the corresponding sequences in genomic RNA of tobacco mosaic virus (TMV) and ToMV. The messenger activity of PMMV-S RNA in vitro and the polypeptide translation products made were similar to those of TMV RNA. It therefore seems unlikely that qualitative or quantitative differences in translation in vivo account for the milder symptoms induced by PMMV-S, and its lesser replication, than TMV. The 3′ non-coding region of PMMV-S RNA is 199 nucleotides long and can be folded into the same secondary structure as the RNA of other tobamoviruses.
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Coat Protein of Melon Necrotic Spot Carmovirus is More Similar to Those of Tombusviruses than Those of Carmoviruses
More LessSummaryComplementary DNA copies of the genomic RNA of melon necrotic spot virus (MNSV) have been cloned and the region deduced to encode the coat protein has been sequenced. The putative coat protein coding region, located near the 3′ end of the genome, consists of 1170 nucleotides and has the potential to encode a 390 amino acid protein of M r 41840. Our data show that although MNSV is a carmovirus, its coat protein more closely resembles those of the tombusviruses than those of the carmoviruses sequenced to date, in both the extent of sequence similarity and in the length of the random/arm and protruding domains of the coat protein. Furthermore, dot matrix comparisons revealed sequence similarity between the coat protein protruding domains of MNSV and the cucumber necrosis tombusvirus. This similarity may be involved in one or more of the biological properties these two viruses share, such as the ability to infect cucumbers naturally and to be transmitted by the soil-inhabiting fungus Olpidium radicale.
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Expression of Cowpea Mosaic Virus M RNA in Cowpea Protoplasts
More LessSummaryCowpea mosaic virus (CPMV) M RNA is translated in vitro into two polyproteins of M r values 105 000 (105K) and 95K. Using antiserum against the small capsid protein VP23, these proteins have now been detected in cowpea protoplasts, a few hours after inoculation with CPMV. These proteins could also be detected at later stages of infection, but only when proteolytic processing was inhibited by the addition of ZnCl2. Using antiserum against a synthetic peptide, corresponding to a part of the overlapping C-terminal ends of the 58K and 48K proteins, the 58K protein, which is the amino-terminal cleavage product of the 105K protein, was found in the cytoplasmic fraction of infected protoplasts. The 48K protein, derived from the 95K protein, was detected in both the cytoplasmic and membrane fractions of protoplasts. The presence of the 105K, 95K, 58K and 48K proteins in CPMV-infected protoplasts indicates that separate initiation codons on the M RNA are used in vivo to produce the 105K and 95K polyproteins, as demonstrated in vitro.
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In vitro Translation of Apple Chlorotic Leaf Spot Virus RNA
More LessSummaryApple chlorotic leaf spot virus (ACLSV) RNA was translated in a rabbit reticulocyte lysate. Two major polypeptides of M r 105000 (105K) and 51 K, and some less prominent polypeptides (88K, 66K, 28K and 23K) were produced. The 23K polypeptide was identified as the coat protein on the basis of its electrophoretic mobility and serological reaction to virus antiserum. Time course and immuno-precipitation experiments suggested that the 23K polypeptide might be generated from the 28K polypeptide by post-translational cleavage.
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Volumes and issues
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Volume 105 (2024)
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Volume 104 (2023)
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Volume 103 (2022)
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Volume 102 (2021)
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Volume 101 (2020)
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Volume 100 (2019)
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Volume 99 (2018)
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Volume 98 (2017)
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Volume 97 (2016)
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Volume 96 (2015)
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Volume 95 (2014)
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Volume 94 (2013)
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Volume 93 (2012)
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Volume 92 (2011)
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Volume 91 (2010)
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Volume 90 (2009)
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Volume 89 (2008)
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Volume 88 (2007)
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Volume 87 (2006)
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Volume 86 (2005)
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Volume 85 (2004)
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Volume 84 (2003)
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Volume 83 (2002)
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Volume 82 (2001)
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Volume 81 (2000)
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Volume 80 (1999)
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Volume 79 (1998)
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Volume 78 (1997)
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Volume 77 (1996)
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Volume 76 (1995)
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Volume 75 (1994)
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Volume 74 (1993)
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Volume 73 (1992)
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Volume 72 (1991)
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Volume 71 (1990)
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Volume 70 (1989)
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Volume 69 (1988)
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Volume 68 (1987)
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Volume 67 (1986)
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Volume 66 (1985)
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Volume 65 (1984)
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Volume 64 (1983)
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Volume 63 (1982)
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Volume 62 (1982)
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Volume 61 (1982)
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Volume 60 (1982)
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Volume 59 (1982)
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Volume 58 (1982)
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Volume 57 (1981)
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Volume 56 (1981)
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Volume 55 (1981)
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Volume 54 (1981)
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Volume 53 (1981)
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Volume 52 (1981)
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Volume 51 (1980)
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Volume 50 (1980)
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Volume 49 (1980)
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Volume 48 (1980)
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Volume 47 (1980)
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Volume 46 (1980)
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Volume 45 (1979)
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Volume 44 (1979)
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Volume 43 (1979)
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Volume 42 (1979)
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Volume 41 (1978)
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Volume 40 (1978)
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Volume 39 (1978)
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Volume 38 (1978)
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Volume 37 (1977)
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Volume 36 (1977)
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Volume 35 (1977)
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Volume 34 (1977)
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Volume 33 (1976)
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Volume 32 (1976)
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Volume 31 (1976)
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Volume 30 (1976)
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Volume 29 (1975)
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Volume 28 (1975)
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Volume 27 (1975)
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Volume 26 (1975)
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Volume 25 (1974)
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Volume 24 (1974)
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Volume 23 (1974)
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Volume 22 (1974)
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Volume 21 (1973)
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Volume 20 (1973)
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Volume 19 (1973)
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Volume 18 (1973)
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Volume 17 (1972)
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Volume 16 (1972)
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Volume 15 (1972)
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Volume 14 (1972)
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Volume 13 (1971)
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Volume 12 (1971)
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Volume 11 (1971)
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Volume 10 (1971)
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Volume 9 (1970)
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Volume 8 (1970)
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Volume 7 (1970)
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Volume 6 (1970)
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Volume 5 (1969)
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Volume 4 (1969)
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Volume 3 (1968)
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Volume 2 (1968)
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Volume 1 (1967)