- Volume 74, Issue 8, 1993
Volume 74, Issue 8, 1993
- Review Article
-
-
-
The closteroviruses, capilloviruses and other similar viruses: a short review
More LessIntroduction. The closteroviruses and capilloviruses are diverse groups of structurally similar, flexuous, filamentous plant viruses. However, because of a lack of information of other than a morphological nature the taxonomy of these virus groups and of other similar elongated viruses has been somewhat confused, and to some extent is likely to remain so for some time.
The closterovirus group is characterized by extremely flexuous particles ranging in modal length from 600 to 2000 nm, depending on the virus; the clostero- prefix is derived from the Greek kloster, meaning thread or spindle. Closterovirus particles are uniformly about 12 nm in width and have an easily recognized ‘open’ structure (closterovirus structure and morphology have been reviewed by Tollin & Wilson, 1988 ). The unipartite ssRNA genome is wound much less tightly in closterovirus particles than in other filamentous plant viruses, with a variability in helical pitch for individual virions suggesting relatively weak interactions between the particle subunits, possibly explaining their extreme flexibility.
-
-
- Animal
-
-
-
Involvement of cellular adhesion sequences in the attachment of adenovirus to the HeLa cell surface
More LessImmunofluorescence analysis of HeLa cells incubated with human adenovirus serotype 2 (Ad2) inoculum suggested that Ad2 receptors co-localized with the receptors of fibronectin (FNR) and vitronectin (VNR) at the cell surface. Ad2 adsorption also resulted in the occurrence of intracytoplasmic actin cables with submembranal anchorage. The cell binding of Ad2 virions, pentons and fibres was found to be efficiently inhibited by concanavalin A, laminin, anti-FNR and anti-VNR antibodies. Arginine-glycine-aspartyl tripeptide (RGD) and other related peptides reproducing cellular attachment sequences of adhesion proteins also competed with Ad2 for cell adsorption, and drastically reduced the virus progeny yield at the end of the infectious cycle. Data from binding competition assays with Ad2 virions showed that the apparent affinity constants of RGD motif-containing peptides for Ad2 receptor ranged from 0·75 × 108 m -1 to 2.2 × 108 m -1, with a number of peptide recognizing sites varying from 1·5 × 104 to 9 × 104 per cell for the different peptides studied. Polypeptide analysis of labelled plasma membrane fractions isolated after cross-linking to unlabelled Ad2 virions showed three major protein species with apparent M r of 130K, 60K and 44K, respectively, reacting with anti-FNR and anti-VNR antibodies. These results suggested that Ad2 and extracellular matrix proteins recognize similar adhesion sequences at the surface of HeLa cells, or alternatively that integrins and Ad2 receptors have overlapping ligand specificity.
-
-
-
-
Human polyomavirus JC promoter/enhancer rearrangement patterns from progressive multifocal leukoencephalopathy brain are unique derivatives of a single archetypal structure
More LessWe have compared the promoter/enhancer structure of human polyomavirus JC (JCV) isolates from 11 progressive multifocal leukoencephalopathy brains. The duplications and deletions of the regulatory region were different in each patient, and usually only one sequence was found in each. The sites of strand breakage in the promoter were not random; four or five preferred sites or areas exist. Alignment of the JCV prototype Mad-1 regulatory region with the unduplicated archetypal structure defines six blocks of sequence, A to F. The preferred sites of strand breaks delineate these regions, although Mad-1 is an unusual promoter containing a break site not observed in other isolates, and an additional site is targeted in several promoters. Region A, containing the TATA box, and the first half of region C, containing several enhancer elements, and region E are consistently retained. Region B, the 23 bp insertion in the archetypal structure (relative to Mad-1) was also retained in all 11 isolates. Region D, the 66 bp insertion, was retained in isolates from three patients. Regions A and D were never duplicated, whereas regions C and E usually were duplicated or triplicated. Variation in the exact point of breakage within the preferred sites, alternative use of the sites in individual promoters and occasional short deletions at other sites result in sequences that are unique in each case. At the same time, the limited choice of break sites and the characteristic fates of the regions themselves result in three broad patterns of repeat sequences. The patterns do not correspond to the viral genotypes 1 and 2 defined by coding region base changes, and do not appear to be a stable feature of the virus. Rather, rearrangements appear to be generated in the host from a basic archetypal sequence.
-
-
-
Antigenic differences between the major glycoproteins of bovine herpesvirus type 1.1 and bovine encephalitis herpesvirus type 1.3
More LessDifferences in the antigenic structure of the major glycoproteins, gI, gIII and gIV, of bovine herpesvirus type 1∙1 (BHV1∙1) and the neurovirulent BHV1∙3 were demonstrated with a panel of monoclonal antibodies (MAbs) prepared against the BHV1∙1 glycoproteins. Glycoprotein gIII of BHV1∙3 was the most dissimilar, reacting with only four of 15 gIII-specific MAbs. Glycoproteins gI and gIV of BHV1∙3 reacted with eight of 11 and eight of 12 specific MAbs, respectively. Monospecific bovine antisera to the two viruses supported findings from the MAb analysis in that gI and gIV glycoproteins were cross-recognized, but gIII was not. Virus-neutralizing MAbs reactive to each glycoprotein and which reacted with both viruses also neutralized both viruses. Previously undescribed glycoproteins which were antigenically related to the intact gIII glycoproteins, but of reduced sizes and lacking at least one gIII epitope, were found for both viruses. Tunicamycin inhibition experiments and immunoprecipitation data suggested that these proteins were intracellular degradation products. Comparisons of the peptide footprints of the glycoproteins from the two viruses using protease V8 digestion after immunoprecipitation with cross-reactive MAbs revealed distinctive footprint patterns for the respective glyco-proteins.
-
-
-
The effects of lithium and potassium on macromolecular synthesis in herpes simplex virus-infected cells
More LessAll herpes simplex virus (HSV) infected cell-specific polypeptides (ICSPs) were synthesized in the presence of lithium at a concentration (60 mm) inhibitory to the production of infectious virus. Yields of certain ICSPs were increased and others, in particular glycoprotein C, decreased. HSV DNA synthesis was completely inhibited; synthesis and in vitro activities of HSV DNA polymerase and thymidine kinase were decreased but to a degree insufficient to account for the complete inhibition of HSV DNA synthesis. HSV DNA synthesis was inhibited to an equivalent degree by either incubation with 60 mm-lithium or by potassium starvation; both procedures decreased intracellular potassium by an equivalent amount as adjudged by X-ray microanalysis. We conclude that lithium inhibits HSV DNA synthesis by displacement of potassium from a potassium-dependent biochemical reaction or by other physiological changes brought about by the loss of cellular potassium. The possibility that lithium also directly inhibits a virus replicative event cannot be excluded.
-
-
-
Restricted replication of respiratory syncytial virus in human alveolar macrophages
The cellular factors that regulate infection and replication of respiratory syncytial virus (RSV) in human alveolar macrophages were examined. RSV-exposed alveolar macrophages demonstrated a time-dependent expression of viral glycoproteins, maximal by 24 h post-infection resulting in infection of approx. 38% of the cells. Essentially all (33%) of these freshly isolated alveolar macrophages replicated RSV as shown by infectious centre assays. This RSV-permissive subpopulation of alveolar macrophages consisted primarily of major histocompatibility class II-expressing cells as determined by fluorescence-activated cell sorting. Reinfection of alveolar macrophages did not significantly alter the number of cells infected or capable of replicating RSV. However, in vitro differentiation of alveolar macrophages prior to infection resulted in a significant (P < 0·05), time-dependent decrease (approx. sevenfold) in the number of cells that replicated virus. The mechanism by which cellular differentiation restricted RSV replication is unknown. Production of defective interfering particles did not account for this decrease. Alveolar macrophages infected with RSV produce a variety of cytokines potentially contributing to this restricted viral replication. Pretreatment with several of these cytokines did not affect viral infection or replication. However, tumour necrosis factor (TNFα) significantly (P < 0·05) decreased viral replication but only by 30 to 60%. Thus RSV replication is reduced by in vitro differentiation of alveolar macrophages and, to a lesser degree, by pretreatment with TNF.
-
-
-
Structural and functional studies on a unique linear neutralizing antigenic site (G5) of the rabies virus glycoprotein
The core of a unique linear neutralization epitope (G5) on the glycoprotein of rabies virus, recognized by a virus-neutralizing mouse monoclonal antibody (MAb 6-15C4), was determined by Pepscan analysis. The G5 epitope was defined as an octapeptide (LHDFRSDE). The contribution of the individual amino acids of the G5 epitope to the binding of MAb 6-15C4 was analysed with a set of synthetic peptides in which the individual amino acids had been replaced in turn by each of the other 19 naturally occurring amino acids. Five amino acids of the octapeptide proved to be essential for the binding of MAb 6-15C4. The conservation of the G5 epitope within the glycoprotein of the different rabies virus strains sequenced to date proved to be absolute at the amino acid level. Studies concerning the immunodominance of the G5 epitope were carried out by determining the presence of G5 epitope-specific serum antibodies in vaccinated humans and mice, and by determining the frequency of G5 epitope-specific B lymphocytes in the blood of vaccinated humans. These studies indicated that antibodies to the G5 epitope constitute a minor population of the rabies virus-specific serum antibodies induced by rabies vaccination.
-
-
-
Identification of a fifth neutralizable site on type O foot-and-mouth disease virus following characterization of single and quintuple monoclonal antibody escape mutants
More LessA monoclonal antibody (C3) produced against foot-and-mouth disease virus type O1Caseros was found to neutralize quadrivalent monoclonal antibody escape mutant (G67) of foot-and-mouth disease virus type O1Kaufbeuren. This mutant had been characterized at the sequence level as having distinct changes affecting four non-overlapping neutralizable sites. The C3 monoclonal antibody was used to prepare a quintuple escape mutant from the G67 and a single escape mutant from the parental O1Kaufbeuren viruses. Polyclonal postvaccinated and infected cattle sera as well as polyclonal mouse and guinea-pig sera, which neutralized the quadrivalent mutant, no longer neutralized the quintuple mutant, indicating that a fifth site had been identified and that changing the fifth site eliminated all neutralization. The site was characterized using serological techniques and found to be conformationally dependent, trypsin-sensitive and independent of sites previously characterized by monoclonal antibodies. Amino acid sequencing comparing parental, single C3 and quintuple mutants showed that a single change from a glutamine to a histidine, at amino acid 149 in the structural protein VP1, (1D) characterized the C3 mutation. The fifth site probably represents a conformational epitope which is formed due to the interaction of the VP1 loop region with other surface amino acids.
-
-
-
Morphological and genomic characterization of two reoviruses (P and W2) pathogenic for marine crustacéans; do they constitute a novel genus of the Reoviridae family?
More LessP and W2 viruses are pathogenic in two crustacéans of the Mediterranean Sea, Macropipus depurator and Carcinus mediterraneus, respectively. Investigation of virus, virus density and genome structure leads us to propose their classification in a genus similar to aquareovirus of the Reoviridae family. They differ from aquareoviruses by the number of dsRNA segments forming the genome (12 instead of 11), their electrophoretic pattern in PAGE (1/5/6 instead of 3/3/5), and the absence of virus replication in fish cell lines.
-
-
-
The genetic basis for the antigenicity of the VP2 protein of the infectious bursal disease virus
More LessThe genomic region coding for the antigenic structure responsible for the induction of neutralizing antibodies was localized in the central variable region of the VP2 gene by comparing the nucleotide sequence of five escape mutants derived from the standard infectious bursal disease virus strain Cu-1. Exchange of a single amino acid at one of the prominent hydrophilic parts of this region proved to be sufficient for altering the neutralizing properties. The reactivity of neutralizing antibodies with peptides expressed in vitro encompassing both hydrophilic areas suggests that the entire variable region is engaged in the formation of this conformation-dependent antigenic site. VP2-specific, non-neutralizing monoclonal antibodies directed against the sequence-dependent epitope of the serotype I strain Cu-1 and the serotype II strain 23/82 cross-reacted with peptides located towards the carboxy terminus of VP2; no reaction occurred with peptides derived from the amino-terminal side adjacent to the variable region.
-
-
-
The AP-1 binding site in the feline immunodeficiency virus long terminal repeat is not required for virus replication in feline T lymphocytes
Sequences of 31 bp containing putative AP-1 and AP-4 binding sequences in the U3 region of the feline immunodeficiency virus (FIV) long terminal repeat (LTR) were deleted and the basal promoter activity of the LTR was measured by the chloramphenicol acetyltransferase (CAT) assay. The activity of the FIV LTR was reduced in Felis catus whole foetus 4 (fcwf-4) cells and Crandell feline kidney cells by this deletion. Cotransfection of murine c-Fos or c-Jun expression plasmids with the FIV LTR-CAT reporter plasmid into fcwf-4 cells revealed that FIV LTR could be activated by c-Fos but not c-Jun in the cells. The mutated LTR was introduced into an infectious molecular clone of FIV and the replication rate and the cytopathogenic activity of the mutant were compared with those of the wild-type in two feline CD4-positive T lymphoblastoid cell lines. It was found that the rate and activity of the mutant were almost the same as those of the wild-type. From these data, we conclude that the 31 bp fragment is important for achieving maximal expression of the FIV genome, but not required for the replication of FIV in feline T lymphocytes.
-
-
-
Identification of cellular proteins that bind to the human immunodeficiency virus type 1 nef gene product in vitro: a role for myristylation
More LessThe human immunodeficiency virus (HIV) type 1 nef gene product was expressed as an N-terminal fusion protein with glutathione-S-transferase (GST) in the baculovirus system. The resulting nefGST fusion protein was found to be authentically myristylated at the N terminus and could be purified to homogeneity by one-step affinity chromatography on immobilized glutathione. The high affinity of nefGST for glutathione was exploited to develop an assay to identify cellular proteins capable of interacting with nef. Several such proteins were identified in extracts from the Jurkat human T cell line. The interaction between nef-binding proteins and immobilized nefGST could be specifically competed by the addition of soluble nef. Cell fractionation showed that nef-binding proteins were present in both cytosolic and membrane-associated fractions. A non-myristylated derivative failed to bind to the membrane-associated proteins but was able to bind to the cytosolic group, albeit with reduced affinity. In addition, a single protein present in both soluble and membrane-associated fractions exhibited myristylation-independent binding to nef. By analogy with other myristylated proteins such as MARCKS (myristylated alanine-rich C kinase substrate) and the Rous sarcoma virus transforming protein, src, the membrane-associated proteins that bind only to myristylated nef may represent a specific membrane target for nef. The cytosolic proteins that interact with nef may constitute soluble components of an as yet unidentified signal transduction pathway which is the target of nef action in the HIV-1-infected cell.
-
-
-
Characterization of an early gene coding for a highly basic 8.9K protein from the Orgyia pseudotsugata multicapsid nuclear polyhedrosis virus
More LessA new gene of the baculovirus Orgyia pseudotsugata multicapsid nuclear polyhedrosis virus (OpMNPV) has been identified that encodes a highly basic 8.9K protein. The gene called p8.9 is expressed as a 0.5 kb transcript by 1 h post-infection and initiates at an early gene motif. The promoter of the 0.5 kb transcript has two upstream elements, repeats I and II, which are similar to motifs previously characterized in the OpMNPV IE-2 gene and the Autographa californica nuclear polyhedrosis virus IE-N and PE38 genes. A second p8.9 transcript expressed from 8 to 72 h post-infection was shown to initiate 634 bp upstream from the early gene motif in a region that has no similarity to any previously described baculovirus promoter or initiation site. Transient assays utilizing a reporter gene have shown that the p8.9 early promoter is active in a Lymantria dispar (LD652Y) and Spodoptera frugipeda (Sf9) cell lines in the absence of other viral factors. In addition, it was also demonstrated that the p8.9 promoter is trans-activated by the OpMNPV IE-2 and p34 genes, but not by IE-1.
-
-
-
Replication of Cydia pomonella granulosis virus in cell cultures
More LessSeveral primary cell lines that support the complete replication of Cydia pomonella granulosis virus have been established from one culture of C. pomonella embryonic cells. Virus passaged three times in cells and once in larvae showed no change in restriction enzyme fragment patterns. Stages in virus replication observed by electron microscopy resembled those from in vivo studies. Cell lines that were maintained at or below 21 °C retained susceptibility to virus over a period of 4 years whereas the same cell lines maintained at 27 °C gradually lost their susceptibility and eventually could not be infected at all.
-
-
-
Nucleotide sequence of the Buzura suppressaria single nucleocapsid nuclear polyhedrosis virus polyhedrin gene
More LessA portion of the genome of the Buzura suppressaria (Lepidoptera) single nucleocapsid nuclear polyhedrosis virus (BsSNPV) containing the polyhedrin gene was sequenced. An open reading frame of 738 nucleotides encoded a protein of 246 amino acids and represented the polyhedrin gene. A conserved TAAG motif, associated with transcriptional start sites in other polyhedrin genes, was identified 51 nucleotides upstream of the BsSNPV polyhedrin gene. A putative polyadenylation signal, AATAAA, was found immediately downstream of the polypeptide termination codon. Comparison of the amino acid sequence of BsSNPV polyhedrin with other NPV polyhedrins and granulosis virus granulins showed that the BsSNPV polyhedrin was most closely related to the polyhedrin of Orgyia pseudotsugata (Lepidoptera) SNPV and most distantly related to the polyhedrin of Neodiprion sertifer (Hymenoptera) SNPV.
-
-
-
Characterization of a single SA7-like VA RNA gene in subgroup F adenoviruses
AH Kidd and CT TiemessenThe virus-associated (VA) RNA gene regions of the human subgroup F adenoviruses (types 40 and 41) were amplified using primers corresponding to flanking open reading frames of human and simian (SA7) adenovirus sequences previously published. The subgroup F adenoviruses, like human Ad12 (subgroup A) and SA7, were found to have only one VA RNA gene at this locus (map unit 30). The type 40 and type 41 VA RNA genes have primary sequence characteristics in common with other known VA RNA genes, have high cross-identity (93%), and show appreciably higher identity to the single VA RNA gene present in SA7 (77% and 81%, respectively) than to any of the VA RNA genes of Ad2, Ad7 or Ad12 (< 61%). These findings may have implications for explaining the evolution and growth peculiarities of human subgroup F adenoviruses.
-
-
-
Identification of a new hepatitis B virus (HBV) genotype from Brazil that expresses HBV surface antigen subtype adw4
The complete genome of a hepatitis B virus (HBV) from Brazil that expressed the subtype adw4 of HBV surface antigen (HBsAg) was cloned and sequenced. The genome, termed w4B, consists of 3215 bp. The overall genetic organization of typical hepadnaviruses with four open reading frames including the preC region was found to be conserved. When comparing the w4B sequence with 19 complete HBV genomes it was, however, found to be more divergent (15%) than any other HBV sequence thus far reported. Until now, no more than 11% divergence has been reported. Distinct from the five known HBV genotypes A to E, w4B made up a new, sixth genotype. The importance of the conserved third start codon in the HBV X gene became apparent in isolate w4B. By mutation, this ATG was out of frame, and by what appears to have been a linked mutation, a new start site two codons downstream was re-established. The significance of several other mutations is discussed.
-
-
-
African swine fever virus thymidylate kinase gene: sequence and transcriptional mapping
More LessA putative thymidylate kinase gene of African swine fever virus has been identified at the left end of the SalI I′ fragment of the virus genome. The gene, designated A240L, has the potential to encode a protein of 240 amino acids with an M r of 27754 and is transcribed early after infection. Primer extension analysis indicates that transcription is initiated a short distance from the first ATG codon of open reading frame A240L. The deduced amino acid sequence of this open reading frame shows significant similarity with the human, yeast and vaccinia virus thymidylate kinases, the degree of identity being 23·7, 25 and 23·5%, respectively. The putative African swine fever virus thymidylate kinase sequence is essentially collinear with the other thymidylate kinase sequences, but contains a carboxy-terminal extension of 37 amino acids rich in glutamic and aspartic acids. The A240L protein conserves the ATP-binding and nucleotide/nucleoside-binding domains characteristic of thymidylate kinases.
-
-
-
Characterization and mapping of simian varicella virus transcripts
More LessThe size and genomic location of viral transcripts expressed in simian varicella virus (SVV)-infected Vero cells were determined. Total cellular RNA and polyadenylated RNA were isolated from SVV-infected and mock-infected Vero cells. Viral transcripts were detected by Northern blot hybridization analysis using overlapping SVV DNA probes representative of the entire SVV genome. The results indicated that all regions of the SVV genome are transcribed during SVV infection in vitro. At least 53 distinct viral RNA species ranging in size from 9·2 to 0·8 kb were detected. DNA probes derived from the SVV DNA long (L) and short (S) components hybridized to 44 RNAs (9·2 to 0·8 kb) and nine RNAs (4·9 to 0·8 kb), respectively. A transcript map of the SVV genome was constructed. The comparison made between the transcript maps of SVV and varicellazoster virus (VZV) provides further support that the SVV and VZV genomes have an analogous gene organization.
-
-
-
Identification of a human cytomegalovirus mutant in the pp150 matrix phosphoprotein gene with a growth-defective phenotype
More LessFollowing amplification by PCR of a portion of the matrix phosphoprotein pp150 gene, electrophoretic analysis revealed the simultaneous presence of two viral variants of human cytomegalovirus in the blood of a heart transplant recipient. Repeated denaturation-annealing cycles during the amplification reaction led to the formation of heteroduplex molecules with altered electrophoretic mobility. Sequence analysis of the amplification products showed the presence of a viral variant carrying an in-frame three nucleotide deletion, which caused the absence of an aspartic acid in the corresponding protein. Attempts to plaque-purify the deletion mutant were unsuccessful, suggesting that the variant was growth-defective.
-
-
-
Inducible expression of a foreign gene inserted into the human cytomegalovirus genome
More LessWe previously described the insertion of a foreign gene into a non-essential region of human cytomegalovirus (HCMV) by homologous recombination. Here we report insertion of the Escherichia coli lacZ gene downstream of the mouse metallothionein promoter into the HindIII-O region of HCMV by replacement-type recombination. Expression of the lacZ gene in the recombinant was independent of viral growth, but dependent on induction by heavy metals. Of several metals tested for β-galactosidase induction and also for their toxicity to HEL cells, Zn was found to be the most suitable for use as an inducer. In HEL cells infected with the recombinant in the presence of 50 μm-Zn, β-galactosidase activity was maximal 3 days after infection, and reached levels 27 times higher than the value obtained in the absence of Zn.
-
-
-
Lipopolysaccharide inhibits the production of lymphocytic choriomeningitis virus in a human monocytic cell line
More LessThe human monocytic cell line THP-1 was used as a model to study the mechanism of infection in the monocyte/macrophage, a natural target of lymphocytic choriomeningitis virus (LCMV) infection in vivo. Both the virulent strain, LCMV. WE, and the avirulent strain, LCMV. ARM, infected THP-1 cells, but did not stimulate THP-1 cells to secrete interleukin 1 (IL-1) or tumour necrosis factor (TNF-α). When lipopolysaccharide (LPS) was added to THP-1 cells together with LCMV, an 80 to 90% reduction in the number of infected cells (measured by immunofluorescence) and a 90% reduction in viral plaques was observed 5 to 6 days postinfection. Neither interferon α (IFN-α) nor IFN-β were detected in supernatants from THP-1 cells after the addition of LCMV, LPS, or LPS plus LCMV. In contrast, the same levels of IL-1 and TNF-α were observed in the presence of LPS and LCMV, or LPS alone. However, antibodies to IL-1, TNF-α, interleukin 6 and IFN-α did not block the antiviral effect of LPS. In kinetic studies, LPS added 1 day after adding LCMV to THP-1 cells was still effective in reducing the number of infected cells. Our findings suggest that LPS alters cellular metabolism, possibly through the induction of IFN-α, and that IFN-α in the absence of LPS suppresses virus production.
-
-
-
Molecular and antigenic characterization of HV114, a hantavirus isolated from a patient with haemorrhagic fever with renal syndrome in China
More LessThe relationship of a Hantaan-like virus (HV114), isolated from a patient with haemorrhagic fever with renal syndrome in Hubei Province, People’s Republic of China, to other pathogenic hantaviruses was evaluated by cross-neutralization studies and nucleotide sequence analysis of the M genome segment. Plaque reduction neutralization assays indicated that HV114 is closely related to prototype Hantaan (HTN) virus, strain 76-118, which was originally isolated from an Apodemus field mouse in Korea. Comparison of the M genome segments of HTN 76-118 and HV114 revealed sequence identity of 84·7% and 95·4% for nucleotides and deduced amino acids, respectively. These data demonstrate that HV114 and 76-118 are two closely related but different isolates of HTN virus, establishing the scientific basis for testing and future use in China of a recombinant vaccine expressing the genome of HTN virus strain 76-118.
-
-
-
Construction of an antigenic map of the haemagglutinin–esterase protein of influenza C virus
More LessFour different antigenic sites (A-1, A-2, B-1, B-2) have been identified previously on the haemagglutinin–esterase (HE) glycoprotein of influenza C/Ann Arbor/1/50 virus with seven monoclonal antibodies (MAbs). In this study we produced 30 additional anti-HE MAbs, nine of which demonstrated at least one of the following activities: haemagglutination inhibition, receptor-destroying enzyme inhibition, haemolysis inhibition, and neutralization (group A). The remaining had none of these activities (group B). These antibodies, and those previously isolated, were used to construct a more complete antigenic map of the HE molecule. Operational and topological analyses showed that a minimum of nine non-overlapping or partially overlapping antigenic sites were present on the HE protein, five recognized by group A MAbs (A-1 to A-5) and four by group B (B-1 to B-4). Among these antigenic sites, site A-5 was unique in that MAbs to this site inhibited the receptor-destroying activity without influencing the receptor-binding activity, which supports the idea that the sites responsible for these two functions are separate. It was also found that several group B MAbs were cross-reactive with host cell antigens.
-
-
-
Location on the evolutionary trees of the non-structural protein (NS) and neuraminidase (NA) genes of late human influenza A (H2N2) viruses: parental viruses of the NS and NA genes of Hong Kong influenza A (H3N2) viruses
More LessThe nucleotide sequences of the non-structural protein (NS) and neuraminidase (NA) genes of human influenza A (H2N2) viruses isolated in 1967 and 1968 in Europe, Asia and North and South America were located on evolutionary trees in order to identify the parental virus of Hong Kong influenza A (H3N2) viruses, which appeared in the human population in 1968. From the evolutionary trees, the H2N2 viruses isolated during the 1967 to 1968 period were divided into two groups. Group I includes the A/Tokyo/3/67, A/Hachioji/1/67, A/Perg/1/68, A/Cordoba/522/67, A/Texas/2/68 and A/Berkeley/1/68 viruses, whereas group II includes the A/Georgia/1/67, A/England/10/67 and A/Poland/6/67 viruses. The NS and NA genes of Hong Kong H3N2 viruses isolated in 1968 were genetically closer to those of group II viruses and closest to those of A/Poland/6/67.
-
-
-
Production of the M2 protein of influenza A virus in insect cells is enhanced in the presence of amantadine
More LessRecombinant baculoviruses that express the M2 protein from the genes of either the amantadine-sensitive, influenza A/Ann Arbor/6/60 virus or a laboratory-derived, amantadine-resistant mutant of this virus were constructed. Addition of amantadine or rimantadine at 2 µg/ml to cultures of Sf9 cells infected with the recombinant baculoviruses increased the yield of the M2 protein from the amantadine-sensitive virus approximately 10-fold, but did not increase the yield of the M2 protein from the amantadine-resistant virus. Flow cytometry demonstrated that the increased production of M2 in the presence of amantadine resulted in increased cell surface expression of the M2 protein. Pulse-chase experiments indicated that whereas the rate of synthesis of the M2 protein increased in the presence of amantadine, the M2 protein was stable in both the presence and absence of amantadine. Addition of amantadine to Sf9 cells as late as 72 h after infection with the recombinant virus increased the production of M2 protein. These data suggest that the M2 protein exerts some biological activity in Sf9 cells.
-
-
-
Characterization of the gene encoding the A-type inclusion protein of camelpox virus and sequence comparison with other orthopoxviruses
More LessA gene was identified in camelpox virus strain CP-1 that is similar to the 160K gene of cowpox virus strain Brighton (BR) that encodes the A-type inclusion body protein (ATIP). The CP-1 gene was mapped, sequenced, and the presence of the ATIP-specific mRNA was demonstrated. The open reading frame [2178 nucleotides (nt)] was found at a similar position in the CP genome as the one reported for the cowpox virus 160K ATI gene. DNA sequence comparison revealed a deletion of two adjacent adenine residues relative to cowpox virus BR, generating a reading frame shift accompanied by the formation of a translational stop codon. An identical deletion has been described for vaccinia virus strain Western Reserve. The DNA sequence of the corresponding region of monkeypox virus strain Copenhagen revealed a deletion leading to a putative stop codon 75 nt upstream of the same stop codons in the camelpox and vaccinia virus genes. These findings are consistent with the expression of truncated ATIPs, of 94K in vaccinia and camelpox viruses and of 92K in monkeypox virus. In addition, a deletion of 789 bp could be localized downstream of the ATI open reading frame in camelpox virus isolates of different origin. This causes the transcription of a shortened ATI-specific mRNA (3·7 kb) relative to vaccinia and cowpox viruses (both 4·5 kb). The similarity observed in ATIP-encoding and flanking sequences might suggest that vaccinia and camelpox viruses are descended from a common ancestor.
-
-
-
Antiviral effect of short hyperthermic treatment at specific stages of vesicular stomatitis virus replication cycle
More LessStarting from the observation that the antiviral activity of cyclopentenone prostaglandins is associated with the synthesis of a 70K heat shock protein (HSP70), we have analysed the effect of short hyperthermic treatment (HT) on HSP70 induction and virus production in monkey epithelial cells during the replication of vesicular stomatitis virus (VSV). The heat shock response, as determined by HSP70 synthesis, appeared to be unaltered in VSV-infected cells in the first 4 h following virus infection, after which time it started to decline. No induction of HSP70 synthesis was observed when HT was applied 8 h after VSV infection. A 20 min HT at 45 °C was effective in suppressing VSV multiplication by more than 90% when applied at specific stages of the virus replication cycle. Synthesis of virus proteins was not affected by HT, indicating that the target for the treatment is a post-translational event. The HT-induced block of virus replication appeared to be associated with inhibition of VSV G protein maturation and HSP70 induction.
-
-
-
Sindbis virus pathogenesis: phenotypic reversion of an attenuated strain to virulence by second-site intragenic suppressor mutations
More LessMonoclonal antibodies (MAbs) specific for the E2c neutralizing antigenic site on the Sindbis virus E2 glycoprotein define a pathogenesis domain that affects neonatal mouse virulence. Sequence analysis of E2c MAb escape mutants showed that the domain included E2 amino acids 62, 96 and 159. The pathogenesis domain is also influenced by changes at E2 position 114. Mutation of E2 residues Asn 62 to Asp or Lys 159 to Glu results in suppression of the attenuated phenotype conferred by a mutation from Ser to Arg at E2 position 114. Possible mechanisms of phenotypic suppression within the E2c pathogenesis domain were investigated by using site-directed mutagenesis to determine the effects of specific combinations of positively charged, negatively charged and uncharged amino acid substitutions at E2 positions 62, 114 and 159. Phenotypic reversion to virulence by second-site suppressor mutations at E2 amino acids 62 or 159 was not dependent on ionic interaction with the residue at E2 114. Rather, suppression appeared to be the result of independent virulence effects mediated by specific residues.
-
-
-
Subgenomic RNAs of Lelystad virus contain a conserved leader-body junction sequence
More LessDuring the replication of Lelystad virus in alveolar lung macrophages, a 3′-coterminal nested set of six subgenomic RNAs (RNA2 to RNA7) is formed. These contain a common leader sequence derived from the 5′ non-coding region of the genomic RNA. In this study, the sequence of the junction sites, i.e. the sites where the leader sequence joins to the body of the subgenomic RNA, was determined for all six subgenomic RNAs. For each subgenomic RNA, six to nine cDNA clones were isolated by means of reverse transcription and PCR. The nucleotide sequence at the junction site was identical for all eight cDNA clones derived from subgenomic RNA4. However, heterogeneity was observed in the nucleotide sequence surrounding the junction sites of the cDNA clones derived from subgenomic RNAs 2, 3, 5, 6 and 7. This heterogeneity suggests that the fusion of the leader to the body of the subgenomic RNA may be imprecise. The junction sites of the six subgenomic RNAs had a conserved sequence motif of six nucleotides (UCAACC or a highly similar sequence). The distance between the junction site and the translation initiation codon of the downstream open reading frame varied from nine to 83 nucleotides.
-
-
-
St Louis encephalitis virus establishes a productive, cytopathic and persistent infection of Sf9 cells
More LessThe Sf9 cell line, commonly used for gene expression by recombinant baculovirus, has been productively infected by St Louis encephalitis (SLE) virus, a flavivirus. SLE viral infection produced a c.p.e. in the Sf9 cells characterized by giant cells and the presence of 10-fold fewer cells in the infected cultures after the first week of infection compared with uninoculated control cultures. Infected Sf9 cells expressed SLE viral antigens, and intracellular virus particles were observed by electron microscopy. Titres of cell-associated SLE virus rose slightly over an 8 week period, whereas titres of cell-free virus remained stable, suggesting that SLE virus establishes a productive and persistent infection of Sf9 cells. The SLE virus produced by the Sf9 cells could be neutralized by SLE virus-immune mouse ascitic fluid, and no evidence of escape mutants was detected. Sf9 cells persistently infected with SLE virus could be superinfected with a recombinant baculovirus and expressed recombinant antigen. The successful infection of Sf9 cells by SLE virus represents the first report of production of c.p.e. by SLE virus in insect cells under routine cell culture conditions and of the infection of Sf9 cells by a human pathogen.
-
-
-
Nucleotide sequence comparison of the VP8* gene of rotaviruses possessing the AU-1 gene 4 allele
Of the five currently recognized alleles of the human rotavirus VP4 gene, the AU-1 allele has captured attention because of its possible non-human origin. The 5′ 750 nucleotide region of the VP4 gene, encoding the VP8* fragment [amino acids (aa) 1 to 241] and the connecting peptide (aa 242 to 247), from 13 human and two feline rotavirus strains possessing the AU-1 allele was highly conserved both at the nucleotide sequence (93·8 to 99·7% identity) and amino acid level (95·5 to 100% identity) irrespective of the year and the place of isolation or of the host species from which these viruses were isolated. This is consistent with the hypothesis that the AU-1 allele of the VP4 gene has been maintained in both human and feline rotavirus gene pools.
-
- Plant
-
-
-
A strong-stop DNA in rice plants infected with rice tungro bacilliform virus
Yiming Bao and Roger HullA virus-specific small nucleic acid (strong-stop DNA) was identified in rice plants infected with rice tungro bacilliform virus, but not in the virus particles. This nucleic acid was shown to consist of about 595 deoxyribonucleotides with about 70 ribonucleotides covalently linked at the 5ʹ end. Hybridization with sequence-specific oligonucleotides showed that the ribonucleotides were from the plant cytoplasmic tRNAMet i sequence. PCR analysis detected hairpin structures at the 3ʹ end of the DNA.
-
-
-
-
Sequence and structure of defective interfering RNAs associated with cucumber necrosis virus infections
More LessThe presence of symptom-attenuating defective interfering (DI) RNAs in a laboratory culture of cucumber necrosis tombusvirus (CNV) was confirmed. Sequencing of cDNA clones of these DI RNAs revealed that CNV DI RNAs retained sequences from the CNV 5′-untranslated and 3′-terminal regions as well as a portion of the coding region for the 92K protein. Similar sequence arrangements were also observed in symptom-attenuating DI RNAs generated de novo from synthetic wild-type CNV transcripts. A comparison of the sequences and biological activities of these CNV DI RNAs is presented. In co-infections of synthetic wild-type CNV and CNV DI RNAs, prominent RNA species of a higher M r than the DI RNA used in the co-infection were found. The possible nature of these RNA species is discussed.
-
-
-
The involvement of cowpea mosaic virus M RNA-encoded proteins in tubule formation
More LessOn the surface of cowpea protoplasts inoculated with cowpea mosaic virus (CPMV), tubular structures containing virus particles have been found. Such tubular structures are thought to be involved in cell-to-cell movement of CPMV in cowpea plants. To study the involvement of the 58K/48K and capsid proteins of CPMV in the formation of the tubular structures, mutations were introduced into M cDNA clones from which infectious transcripts could be derived. No tubules were found on protoplasts inoculated with a mutant that fails to produce the 48K protein nor with a mutant that has a deletion in the 48K coding region, suggesting that the 48K protein is essential for this process. However, a possible role of the 58K protein in tubule formation could not be excluded. A mutant that fails to produce the capsid proteins did produce tubules and therefore the capsid proteins are not involved in the formation of the tubular structures. Electron microscopic analysis revealed that the tubules produced by this mutant are, apart from the absence of virus particles, morphologically identical to the tubules formed by the wild-type virus.
-
Volumes and issues
-
Volume 105 (2024)
-
Volume 104 (2023)
-
Volume 103 (2022)
-
Volume 102 (2021)
-
Volume 101 (2020)
-
Volume 100 (2019)
-
Volume 99 (2018)
-
Volume 98 (2017)
-
Volume 97 (2016)
-
Volume 96 (2015)
-
Volume 95 (2014)
-
Volume 94 (2013)
-
Volume 93 (2012)
-
Volume 92 (2011)
-
Volume 91 (2010)
-
Volume 90 (2009)
-
Volume 89 (2008)
-
Volume 88 (2007)
-
Volume 87 (2006)
-
Volume 86 (2005)
-
Volume 85 (2004)
-
Volume 84 (2003)
-
Volume 83 (2002)
-
Volume 82 (2001)
-
Volume 81 (2000)
-
Volume 80 (1999)
-
Volume 79 (1998)
-
Volume 78 (1997)
-
Volume 77 (1996)
-
Volume 76 (1995)
-
Volume 75 (1994)
-
Volume 74 (1993)
-
Volume 73 (1992)
-
Volume 72 (1991)
-
Volume 71 (1990)
-
Volume 70 (1989)
-
Volume 69 (1988)
-
Volume 68 (1987)
-
Volume 67 (1986)
-
Volume 66 (1985)
-
Volume 65 (1984)
-
Volume 64 (1983)
-
Volume 63 (1982)
-
Volume 62 (1982)
-
Volume 61 (1982)
-
Volume 60 (1982)
-
Volume 59 (1982)
-
Volume 58 (1982)
-
Volume 57 (1981)
-
Volume 56 (1981)
-
Volume 55 (1981)
-
Volume 54 (1981)
-
Volume 53 (1981)
-
Volume 52 (1981)
-
Volume 51 (1980)
-
Volume 50 (1980)
-
Volume 49 (1980)
-
Volume 48 (1980)
-
Volume 47 (1980)
-
Volume 46 (1980)
-
Volume 45 (1979)
-
Volume 44 (1979)
-
Volume 43 (1979)
-
Volume 42 (1979)
-
Volume 41 (1978)
-
Volume 40 (1978)
-
Volume 39 (1978)
-
Volume 38 (1978)
-
Volume 37 (1977)
-
Volume 36 (1977)
-
Volume 35 (1977)
-
Volume 34 (1977)
-
Volume 33 (1976)
-
Volume 32 (1976)
-
Volume 31 (1976)
-
Volume 30 (1976)
-
Volume 29 (1975)
-
Volume 28 (1975)
-
Volume 27 (1975)
-
Volume 26 (1975)
-
Volume 25 (1974)
-
Volume 24 (1974)
-
Volume 23 (1974)
-
Volume 22 (1974)
-
Volume 21 (1973)
-
Volume 20 (1973)
-
Volume 19 (1973)
-
Volume 18 (1973)
-
Volume 17 (1972)
-
Volume 16 (1972)
-
Volume 15 (1972)
-
Volume 14 (1972)
-
Volume 13 (1971)
-
Volume 12 (1971)
-
Volume 11 (1971)
-
Volume 10 (1971)
-
Volume 9 (1970)
-
Volume 8 (1970)
-
Volume 7 (1970)
-
Volume 6 (1970)
-
Volume 5 (1969)
-
Volume 4 (1969)
-
Volume 3 (1968)
-
Volume 2 (1968)
-
Volume 1 (1967)