The family Parvoviridae

A set of proposals to rationalize and extend the taxonomy of the family Parvoviridae is currently under review by the International Committee on Taxonomy of Viruses (ICTV). Viruses in this family infect a wide range of hosts, as reflected by the longstanding division into two subfamilies: the Parvovirinae, which contains viruses that infect vertebrate hosts, and the Densovirinae, encompassing viruses that infect arthropod hosts. Using a modified definition for classification into the family that no longer demands isolation as long as the biological context is strong, but does require a near-complete DNA sequence, 134 new viruses and virus variants were identified. The proposals introduce new species and genera into both subfamilies, resolve one misclassified species, and improve taxonomic clarity by employing a series of systematic changes. These include identifying a precise level of sequence similarity required for viruses to belong to the same genus and decreasing the level of sequence similarity required for viruses to belong to the same species. These steps will facilitate recognition of the major phylogenetic branches within genera and eliminate the confusion caused by the near-identity of species and viruses. Changes to taxon nomenclature will establish numbered, non-Latinized binomial names for species, indicating genus affiliation and host range rather than recapitulating virus names. Also, affixes will be included in the names of genera to clarify subfamily affiliation and reduce the ambiguity that results from the vernacular use of “parvovirus” and “densovirus” to denote multiple taxon levels.     

The family Tymoviridae

Summary. The family Tymoviridae comprises the genus Tymovirus, from which it derives its name, the genus Marafivirus and the newly established genus Maculavirus. Members of the family share the following characteristics: (i) non-enveloped isometric particles c. 30 um in diameter, with a rounded contour and prominent surface structures, and clustering of coat protein subunits in pentamers and hexamers; (ii) the presence in preparations of purified virus particles of two centrifugal components, made up of non-infectious protein shells (T) that may contain small amounts of RNA (primarily subgenomic coat protein mRNA) and of infectious nucleoproteins (B), that contain the virus genome; (iii) possession of a positive-sense, single-stranded RNA genome with an unusually high cytidine content (32 to c. 50%), capped at the 5' terminus and containing a very large ORF encodes replication-related proteins analogous to those of other taxa of the "alpha-like" supergroup of ssRNA viruses; (iv) a replication strategy possibly encompassing posttranslational proteolytic cleavage of the polypeptide encoded by ORF1 by a papain-like virus-encoded protease, and coat protein expression via a subgenomic RNA; (v) the presence in infected cells of cytopathic structures, thought to be the sites of RNA replication, originating from severely altered chloroplasts and/or mitochondria, the periphery of which is lined with vesicles produced by the localized invaginations of the bounding membrane. There are 23, 4, and 2 known species in the genera Tymovirus, Marafivirus and Maculavirus, respectively. The genus Marafivirus also contains one tentative species.     

The family Closteroviridae revised

Summary.  Recently obtained molecular and biological information has prompted the revision of the taxonomic structure of the family Closteroviridae. In particular, mealybug-transmitted species have been separated from the genus Closterovirus and accommodated in a new genus named Ampelovirus (from ampelos, Greek for grapevine). Thus, the family now comprises three genera. Their major properties are (i) Closterovirus: type species Beet yellows virus, genome monopartite, 15.5–19.3 kb in size, a 22–25 kDa major coat protein (CP), the gene encoding the divergent CP analogue (CPd) upstream of the CP cistron, transmission by aphids, a membership of 8 definitive and 4 tentative species; (ii) Ampelo-virus: type species Grapevine leafroll virus 3, genome monopartite 16.9–19.5 kb in size, a 35–37 kDa major CP, a CPd cistron generally located downstream of the CP gene, transmission by pseudococcid and coccid mealybugs, a membership of 6 definitive and 5 tentative species; (iii) Crinivirus: type species Lettuce infectious yellows virus, genome essentially bipartite 15.3–19 kb in size, a 28–33 kDa CP, a CPd cistron downstream of the CP gene, transmission by whiteflies (Bemisia, Trialeurodes), a membership of 7 definitive and 3 tentative species. There are five unassigned species in the family.     

The family medicine cabinet

Medicine selection and storage was examined in 130 families. Over 50 per cent were found to be less than adequate. Health education advice helped half the inadequate group to change to adequate. Age and social class were not related to hoarding of prescribed drugs, to initial standards of storage or selection, nor to the likelihood of a response to advice. Those who hoarded medicines but stored them well were highly likely to change. Those who stored and selected poorly were unlikely to make any changes. The 130 families had an average of 8.6 prescribed drugs per house, over half of which were completely out of date and were not being kept for emergency usage. There were also an average of 14.2 non-prescribed items per house, giving a total of 22.8 per house.