Showing papers on "Virus classification published in 1992"

Mapping functions on the multipartite genome of beet necrotic yellow vein virus

Abstract: Beet necrotic yellow vein virus (BNYVV) is a fungus-transmitted soilborne virus responsible for rhizomania disease of sugar beet (Beta vulgaris L. var. saccharifera). As more and more viruses with fungal vectors are detected (3) these pathogens have been the subject of growing interest, leading to attempts at classification based both upon the nature of the vector and the properties of the virus. In 1987, the International Committee on Virus Taxonomy classified BNYVV as a possible member of the recently proposed furovirus group fungus-transmitted rod-shaped virions; type member: soilborne wheat mosaic virus (SBWMV) (56). Furoviruses have rigid rod-shaped virions, plus-strand RNA genomes, are generally bipartite and are transmitted by soilborne fungi of the family Plasmodiophorales. In addition to SBWMV, other accepted members include beet soilborne virus (BSBV), broad bean necrosis virus (BBNV), oat golden stripe virus (OGSV), peanut clump virus (PCV) and

Genomic 3' terminal sequence comparison of three isolates of rabbit haemorrhagic disease virus.

Abstract: Comparison of sequence data is necessary in older to investigate virus origins, identify features common to virulent strains, and characterize genomic organization within virus families. A virulent caliciviral disease of rabbits recently emerged in China. We have sequenced 1100 bases from the 3′ ends of two independent European isolates of this virus, and compared these with previously determined calicivirus sequences. Rabbit caliciviruses were closely related, despite the different countries in which isolation was made. This supports the rapid spread of a new virus across Europe. The capsid protein sequences of these rabbit viruses differ markedly from those determined for feline calicivirus, but a hypothetical 3′ open reading frame is relatively well conserved between the caliciviruses of these two different hosts and argues for a functional role.

Application of genome sequence information in potyvirus taxonomy: an overview.

Abstract: The application of protein and nucleic acid sequence analysis in evolutionary and phylogenetic studies is well established. Available sequence information for the 5′ untranslated region of potyviruses including the fungus-transmitted barley yellow mosaic virus (BaYMV) RNA-1 suggests that a 12-nucleotide conserved sequence, the “potybox” is unique to this group. Various non-structural proteins of potyviruses share considerable “signature” sequence homology across a broad spectrum of unrelated viruses, which makes their value limited to “supergroup” or “superfamily” identity. However, in potyviruses, the coat-protein N-terminal sequences and 3′ noncoding regions are variable among viruses, but similar among strains of the same virus. This suggests that these sequences may be an accurate marker of genetic related-ness. Until complete genome sequences from a large number of potyviruses become available and their value in systematics is tested, coat protein and 3′ noncoding regions remain as the choice of taxonomic indicators. The reason being, that cloning and sequencing of the coat-protein gene and 3′ noncoding regions are less complicated and time consuming and the sequences show significant differences among the virus species within the family Potyviridae.

Concept of virus species

Abstract: The species concept is applicable in virology because viruses have genomes, replicate, evolve, and occupy particular ecological niches. The following definition of virus species was accepted in 1991 by the International Committee on Taxonomy of Viruses: ‘A virus species is a polythetic class of viruses that constitutes a replicating lineage and occupies a particular ecological niche’. This definition does not provide a list of diagnostic properties for recognizing members of particular virus species. Furthermore, since a virus species is a polythetic class, it is impossible to use a single property such as a certain level of genome homology as defining property of the species. The implications of this new definition of virus species for future virus classification are discussed.

The recombinative nature of potyviruses: implications for setting up true phylogenetic taxonomy.

Abstract: Sequence comparisons reveal that positive-strand RNA viruses not only evolve by divergence from common ancestors but also by interviral recombination A considerable number of these viruses, exemplified by the family Potyviridae, can in fact, be regarded as successful products of a number of recombination events It is concluded that the recombinative character of RNA viruses will hamper any attempt to set up a true phylogenetic taxonomy It is advisable, therefore, to avoid the introduction of any taxon higher-than-family in virus taxonomy

What is a virus

Abstract: The earlier reluctance of some plant virologists to use the term “virus species” has been overcome and the species has now been accepted as the basic unit in virus classification. A virus species is a polythetic class of viruses that constitutes a replicating lineage and occupies a particular ecological niche. Because of the polythetic nature of virus species, there is no single property, such as a particular level of genome homology, that could be used as the sole criterion for delineating individual virus species.

Specific infectivity and host resistance have predicated potyviral and pathotype nomenclature but relate less to taxonomy.

Abstract: The names of potyviruses and viral-strains have represented the occurrence of predominant pathotypes on predominant crop genotypes. Thus virus nomenclature, but not viral taxonomy, has been decisively influenced by plant-genotype susceptibility and indirectly by host genetic resistance. Resistance to infection (i.e., host range) continues to serve a practical role in differentiating recognized viruses. Plant genes that confer disease tolerance or viral resistance remain a principal means of viral pathotype differentiation, as well as a principal control measure against major viral pathogens. Degrees of genetic diversity among isolates of recognized viruses should not be underestimated, and any system of viral taxonomy should be prepared for flexibility at the species level.

Stedman's ICTV virus words

Abstract: This alphabetical compilation of over 2,500 virus names allows users to ascertain the correct spelling of all validly published virus names, identify their taxonomic status, determine the validity of a name, and recognize accepted synonyms. Also included are the complete taxonomy of virus, accepted abbreviations of virus names and diagrams of virus families and groups according to their given major host.

Computerization of virus data and its usefulness in virus classification

Abstract: Data on 537 Arboviruses and 180 other viruses have been collected and coded in two different formats These data include information not only regarding the taxonomy and history of isolation, but also regarding the properties of biomacromolecules, proteins and nucleic acids Information on antigenic relationships, histopathology and experimental viremia is also included This information is stored in formats which allow the manipulation and analysis of data by dBASE III PLUS and MICRO-IS A set of programs was written for interconversion and editing purposes Transmission electron micrographs are scanned and stored This stored information can be used in viral classification as shown by carrying out analysis of data on the Bunyaviridae family

Potential for using transgenic plants as a tool for virus taxonomy.

Abstract: Transgenic plants resistant to viruses don’t behave uniformly enough to be used as a convenient tool for virus taxonomy.