RESUMO
From a panel of 10 monoclonal antibodies (MAbs) prepared against specific isolates representing the three recognized strain groups of potato virus Y (PVY), i.e., common (PVYO), tobacco veinal necrosis (PVYN), and stipple streak (PVYC), seven were selected for serotype analysis. These MAbs were tested for reactivity with 52 PVY strains representing all three strain groups from an international collection. Within the PVYN strain group, five serotypes were identified and designated N1 to N5. The PVYO strain group was more diverse, and nine serotypes were defined and designated O1 to O9. Only one serotype, designated C1, was defined) within the PVYC strain group. The same panel of MAbs was used to test 632 PVY samples collected from potato seed certification plots in North America. Although no PVY(N) serotypes were found, all of the PVYO serotypes were identified, and several samples, tentatively assigned to the C1 serotype, were found.
RESUMO
Monoclonal antibodies (MAbs) were produced against arabis mosaic nepovirus (AMV). A hybridoma screening procedure was applied which involved the testing of culture supernatants, before the hybridomas were cloned to single cell lines, for their reaction with eight nepoviruses [AMV, cherry leafroll virus (CLRV), grapevine fanleaf virus (GFLV), peach rosette mosaic virus, raspberry ringspot virus (RRSV), tobacco ringspot virus, tomato black ring virus (TBRV) and tomato ringspot virus]. In addition to AMV-specific MAbs, this screening technique has allowed the selection of two cross-reacting MAbs: one reacting with AMV and GFLV, and one reacting with AMV and RRSV. This is the first report of MAbs cross-reacting with these nepoviruses. In addition, five heterospecific MAbs (HS-MAbs) could be selected: two reacting with RRSV, two with CLRV and one with TBRV. The usefulness of the screening technique that was applied for the selection of cross-reacting MAbs and HS-MAbs, and the potential use of such antibodies are discussed.
Assuntos
Anticorpos Monoclonais/imunologia , Vírus do Mosaico/imunologia , Células Clonais , Reações Cruzadas , Hibridomas , Vírus do Mosaico/classificação , Vírus do Mosaico/isolamento & purificação , Doenças das Plantas/microbiologia , QuarentenaRESUMO
The sequence of 3553 nucleotides corresponding to the 3'-terminal region of potato virus S (PVS) has been determined from cloned cDNA. The sequence obtained contains six open reading frames (ORFs) encoding proteins of Mr 10,734, Mr 32,515, Mr 7,222, Mr 11,802, Mr 25,092 and at least Mr 41,052. The sequence of the 33K ORF has been confirmed to be that of the viral coat protein gene. The nucleotide sequence of this ORF was obtained from plasmids which were isolated by colony hybridization with a specific monoclonal antibody to PVS, and the expression of coat protein fusion products was verified by Western blots of bacterial cell lystates. The deduced amino acid sequence of a 70 amino acid portion from the central region of the PVS coat protein was 59% identical to the analogous region of potato virus X. In addition, the 7K, 12K and 25K ORFs displayed significant sequence homology with the similarly sized ORFs from a number of potexviruses. The partial 41K ORF product was homologous with the C-terminal portion of the viral replicase proteins of potato virus X and white clover mosaic virus.
Assuntos
Proteínas do Capsídeo , Vírus de Plantas/genética , RNA Viral/genética , Sequência de Aminoácidos , Sequência de Bases , Western Blotting , Capsídeo/genética , Códon/genética , DNA/genética , DNA Viral/genética , Genes Virais , Dados de Sequência Molecular , Plasmídeos , Recombinação Genética , Homologia de Sequência do Ácido Nucleico , Solanum tuberosum/microbiologiaRESUMO
Potato leafroll virus (PLRV) was purified from infected potato (Solanum tuberosum L.) with yields of 0.4-0.6 mg/kg of foliage. The virus sedimented as a single component of 127 S. An antiserum prepared against purified virus had a maximum titer of 1:1024 in agar gel double diffusion tests. PLRV had a buoyant density of 1.39 g/ml and an estimated nucleic acid content of 28%. The nucleic acid had a molecular weight of 2.0 x 10(6) and was degraded by RNase but not by DNase, indicating that the PLRV nucleic acid is RNA. The sedimentation coefficient of the RNA molecule was 34.5 S and after treatment with formaldehyde, 20.7 S. Dissociated coat protein migrated as a single band in polyacrylamide gel electrophoresis and the average subunit molecular weight was 26,300. PLRV should be considered a member of the luteovirus group.
RESUMO
The filamentous particles of poplar mosaic virus (PopMV) were detected in palisade, mesophyll and parenchyma cells of systemically infected leaves of Nicotiana clevelandii and N. megalosiphon. The particles were sometimes found scattered throughout the cytoplasm, but more often they occurred loosely associated within ovoid aggregates (up to 3.5 x 1.5 mum) adjacent to chloroplasts and/or mitochondria. PopMV did not induce the formation of 'pinwheel' inclusions, nor other conspicuous ultrastructural or cytopathic effects in infected cells. These observations provide additional evidence that PopMV is a Carlavirus and not a Potyvirus nor a mite-borne virus. PopMV particles were also detected occasionally within plasmodesmata.
