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Parvovirus Classification

Parvovirus Classification. Kevin E Brown Immunisation and Diagnosis Unit Virus Reference Department Centre for Infections. Classification of Viruses. Prior to 1966 an array of different names/classifications Moscow 1966 – International Congress of Microbiology

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Parvovirus Classification

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  1. Parvovirus Classification Kevin E Brown Immunisation and Diagnosis Unit Virus Reference Department Centre for Infections

  2. Classification of Viruses • Prior to 1966 an array of different names/classifications • Moscow 1966 – International Congress of Microbiology • International Committee on Taxonomy of Viruses (ICTV) • A single taxonomic scheme for all viruses • Naming and classification • 70 Study Groups who provide the information • Regular reports (currently 8th)

  3. ICTV classification • ‘a virus species is a polythetic class of viruses that constitute a replicating lineage and occupy a particular ecological niche’ (7th report) • Polythetic class - several properties in common, but not necessarily a single common defining property • Hierarchy of recognised viral taxa: • (Order); Family; (Subfamily); Genus; Species • ‘Other groupings (from clade to super-family), may communicate useful descriptive information in some circumstances but they have no formally recognized taxonomic meaning’ (8th report, p4)

  4. Demarcation criteria: When is a new virus a new virus? • Pairwise sequence identity profiles: well resolved peaks between strains, species and genera. Different virus families show similar overall patterns. • Genetic analysis should provide validation of taxonomic assignments. Since viruses are polythetic, multiple demarcation criteria are needed to reliably delineate different species. Sequence comparisons are an increasingly dominant (but not the only) criteria.

  5. Parvoviridae • Non-enveloped • 22-24nm icosahedral virion • 4 - 5.6 kb ss linear DNA genome • ITRs at 5’ and 3’ ends • Encode no polymerase • Dependant on cellular/other viral proteins for DNA replication • 2 large ORF • NS (or Rep) proteins • VP (or Cap) proteins

  6. Parvovirus Classification • Host range -2 subfamilies • Densovirinae – insects • Parvovirinae – vertebrates Autonomous/dependant replication + , –, or +/- strand packaging Identical or different 5’ and 3’ ITRs 1, 2 or 3 promoters Sequence phylogeny

  7. + + Parvovirus Taxonomy

  8. Erythrovirus Genus • Encapsidate equivalent numbers of + and – strand • upon extraction anneal to form ds DNA • Long palindromic ITR (~383 nt) • ‘Identical’ ITR at 5’ and 3’ ends • Single mRNA promoter • Polyadenylation signals mid genome and 3’ end • Efficient replication in erythroid precursors

  9. Human Parvovirus B19 (B19V) • Type member of the Erythrovirus family • First identified in 1974 (CPHL, London) • ~ 22 nm icosahedral virion • Linear ss DNA • ~ 5600 nucleotides • Long (383nt) terminal hairpin seq • Complex transcription map • Single promoter (p6) • 1 non-spliced non-structural protein • 2 capsid proteins (VP1 & VP2) -alt splicing • Small proteins of unknown function • VP2 self assembles to form VLP • Erythrotropic • Does not grow in standard tissue culture • Replicates in erythroid progenitors • Rare cell lines (UT7/Epo; KU812Ep6)

  10. A6 V9 Phylogenetic tree of VP1u region Servant et al. J. Virol 2002

  11. Phylogenetic analysis of capsid proteins of the Parvovirinae

  12. Phylogenetic analysis of non-structural proteins of the Erythroviruses

  13. Percent Identity NS proteins Genus Species Strains

  14. List of species in Erythrovirus genus • Type species – human parvovirus B19 • Accepted species • Human parvovirus B19 (B19V) • B19V-A6, B19V-Au, B19V-LaLi, B19V-V9, B19V-Wi • Pig-tailed macaque parvovirus (PmPV) • Rhesus macaque parvovirus (RmPV) • Simian parvovirus (SPV • Tentative species • Bovine parvovirus type 3 (BPV-3) • Chipmunk parvovirus (ChpPV)

  15. Parv4/5 Human Parvoviruses

  16. Parvovirus Study Group • Peter Tattersall, Max Bergoin, Marshall Bloom, Kevin Brown, Michael Linden, Nick Muzycka, Colin Parrish and Peter Tijssen Dr Anne Field (1936-2007)

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