Rotavirus : Classification, Structure, composition and properties

Rotavirus : Classification, Structure, composition and properties


Rotavirus

  • Family: Reoviridae
  • Genus: Rotavirus

Classification of Rotavirus:

  • Classified into seven distinct groups (A to G) based on structural antigen VP6.
  • Group A, B, and C Rotaviruses are found in Human infection as well as animal infection
  • Group A Rotaviruses are most frequent Human pathogen

Structure, composition and properties of Rotavirus

1. Structure:

  • Characteristics ”wheel” like appearance (Rota-means wheel)
  • Size: 65nm-100nm in diameter
  • Shape: Spherical shape
  • Symmetry: Icosahedral

2. Genome composition:

  • Genome: 11 segments of double-stranded RNA (ds RNA )
  • Can undergo genetic reassortment.
  • Protein: 6 structural protein (VP) and 6 Non-structural protein (NSP)
  • Envelope: Absent
  • Nucleic acid is surrounded by two layer of capsid- inner capsid (VP6) and outer capsid (VP7)
  • VP4 is the spike protein, it is a cell surface receptor

3. Other properties

  • Replication: Occurs in cytoplasm of infected cell.
  • Rotavirus contain an RNA-dependent RNA polymerase and other enzymes capable of producing capped RNA transcripts

Rotaviruses are inactivated by-

  • Heating to 100°C
  • Treatment with acid (pH<3),
  • Glutaraldehyde (3%),
  • Phenol,
  • Formalin,
  • Chlorine
  • Alcohol (70%) 

Replication of Rotavirus:

  1. Attachment: by VP4 on cell surface receptor
  2. Penetration: receptor-mediated endocytosis
  3. Un-coating in lysosome
  4. Transcription is mediated by endogenous virus dependent RNA polymerase (transcriptase)
  5. Translation to produce viral structural protein
  6. Synthesis of full-length transcript
  7. Some of the full-length transcript are encapsidate
  8. Synthesis of –ve sense RNA strand with capsid to form ds RNA
  9. Formation of inner capsid
  10. Morphogenesis: budding of single shelled virus into RER acquiring pseudo envelope
  11. Removal of pseudo envelope and replaced by outer capsid in RER
  12. Maturation
  13. Cell lysis and Release
Exam Question
 
  • Rotavirus is a double-stranded RNA virus belonging to the family Reoviridae.
  • Under electron microscope, Rotavirus looks like a wheel.
  • The RNA is enclosed in a triple layered, non enveloped icosahedral capsid.
  • It is one of the commonest cause of watery diarrhoea in children.
  • Oral rehydration therapy is the most appropriate treatment of choice.
  • Segmented genome is found in Rotavirus
  • One unique feature of rotaviruses is the ease with which the 11 RNA segments can undergo reassortment.
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