DNA VIRUS

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Classification of DNA viruses

• Submitted by-

• Submitted to-

• Rekha Panwar

• Prof S. Maherchandani

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VIRUS CLASSIFICATION

• For the first 60 years there was no system
• Named according to the
• associated diseases e,g poliovirus, rabies,
• type of disease caused e.g murine leukemia
  virus,
• sites in the body affected or from which the
  virus was first isolated e.g rhinovirus,
  adenovirus.
• where they were first isolated Sendai virus,
  Coxsackievirus,
• after scientists who discovered them e.g
  Epstein-Barr virus,
• or for the way people imagined they were
  contracted e.g dengue evil spirit influenza
  influence of bad air.
• Two systems
• The Hierarchical
• Baltimore Classification System

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The Baltimore Classification System

• Although many viruses are classified into
  individual families based on a variety of
  physical and biological criteria, they may also
  be placed in groups according to the type of
  genome in the virion.
• Over 30 years ago virologist David
  Baltimore devised an alternative classification
  scheme that takes into account the nature of the
  viral nucleic acid.

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The Baltimore classification system
Based on genetic contents and replication
strategies of viruses. According to the Baltimore
classification, viruses are divided into the
following seven classes
1. dsDNA viruses 2. ssDNA viruses 3.
dsRNA viruses 4. () sense ssRNA viruses
(codes directly for protein) 5. (-) sense
ssRNA viruses 6. RNA reverse transcribing
viruses 7. DNA reverse transcribing
viruses where "ds" represents "double strand"
and "ss" denotes "single strand".
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Virus Classification I- the Baltimore
classification

• All viruses must produce mRNA, or () sense RNA
• A complementary strand of nucleic acid is ()
  sense
• The Baltimore classification has RNA as its
  central point
• Its principles are fundamental to an
  understanding of virus classification and genome
  replication, but it is rarely used as a
  classification system in its own right

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ICTV CLASSIFICATION

• In 2010 the International Committee on Taxonomy
  of Viruses (ICTV) formally recognized
• 6 Orders
• 87 Families
• 19 Subfamilies
• 348 Genera
• and 2285 Species of viruses

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DNA VIRUSES-Dna virus is a virus that has DNA
(deoxyribonucleic acid) as its genetic material.
-They are usually Large, Icosahedral, enveloped
in Lipoproteins-Do not have polymerase enzymes,
and cause Latent infection-Examples include
Poxviruses, Herpesviruses, hepadnaviruses,
Hepatitis b.
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DNA viruses
From Principles of Virology Flint et al ASM Press
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FAMILY SUBFAMILY GENUS SPECIES
Poxviridae Chordopoxvirinae Entomopoxvirinae Orthopoxvirus Capripoxvirus Leporipoxvirus Suipoxvirus Molluscipoxvirus Avipoxvirus Yatapoxvirus Parapoxvirus Entomopoxvirus genera Vaccinia virus Sheeppox virus Myxoma virus Swinepox virus Molluscum contagiosum virus Fowlpox virus Yaba monkey tumor virus Orf virus Insect viruses I
Asfarviridae Asfivirus African swine fever virus
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Iridoviridae Ranavirus Ly mphocystivirus Frog virus 3 Flounder virus
Herpesviridae Alphaherpesvirinae Betaherpesvirinae Gammaherpesvirinae Simplexvirus Varicellovirus Marek's disease-like viruses infectious laryngotracheitis-like viruses Cytomegalovirus Muromegalovirus Roseolovirus l ymphocryptovirus Rhadinovirus Human herpesvirus 1 Human herpesvirus 3 Marek's disease virus Gallid herpesvirus 1 Human herpesvirus 5 Mouse cytomegalovirus Human herpesvirus 6 Human herpesvirus 4 Ateline herpesvirus 2

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Adenoviridae Mastadenovirus Aviadenovirus Proposed, Atadenovirus Human adenovirus 2 Fowl adenovirus 1 Ovine adenovirus 287
Papovaviridae Polyomavirus Papillomavirus Murine polyomavirus Papillomavirus Cottontail rabbit papillomavirus
Single-slranded DNA viruses Parvoviridae Parvovirinae Parvovirus Erythrovirus Dependovirus Minute virus of mice B 19 Adeno-associated virus 2
Circoviridae Circovirus Chicken anemia virus
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HERPESVIRIDAE

• ds DNA
• Icosahedral
• Asymmetrical tegument between capsid and envelope
• Enveloped
• Glycoprotein spikes
• 8 human serotypes
• Latent, recurring infections

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ADENOVIRIDAE

• Linear ds DNA
• Icosahedron
• Nonenveloped
• 12 surface protein fibers project from
  nucleocapsid
• Fiber hemagluttin
• Globe end attach
• Direct or droplet

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PAPOVIRIDAE

• Circular ds DNA
• Icosahedron
• Nonenveloped
• Mixed capsomeres
• Pentavalent
• Hexavalent
• Direct contact

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HEPADNAVIRIDAE

• Partially ds DNA with RNA intermediate
• Icosahedral core
• Outer coat extends as sphere or tail
• Surface HBsAg on coat
• Enveloped
• Parentally
• Direct or Indirect
• Horizontal or vertical

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Family Asfarviridae

• Enveloped,200 nm icosahedral particle with 70 nm
  isometric core, linear ds DNA, cytoplasmic
  replication.
• African swine fever virus

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POXVIRIDAE

• Largest of all viruses
• Linear ds DNA
• Own RNA polymerase
• Biconcave core
• Two linear bodies
• Enveloped
• External coat
• Lipids
• Tubular proteins

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• Viruses with ss DNA genomes
• Family Circoviridae
• Nonenveloped small icosahedral, circular ss DNA
  genome
• Porcine circovirus 1 and chicken anaemia virus
• Family Parvoviridae
• Nonenveloped icosahedral 18-26 nm, linear ss DNA
  genome replication in nuceus.
• Two sub families Parvovirinae (viruses of
  vertebrates) and Densovirinae (viruses of mainly
  insects)

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PARVOVIRIDAE

• ss DNA ( or -)
• Icosahedron
• Nonenveloped
• Smallest DNA virus
• Resp. Droplet spread
• B19 virus
• Targets erythroid cell line, decreases RBCs
• Erythemia infectiosum
• Rash
• Arthritis

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