Rotavirus : Classification, Structure, composition and properties
- 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
- 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%),
- Alcohol (70%)
Replication of Rotavirus:
- Attachment: by VP4 on cell surface receptor
- Penetration: receptor-mediated endocytosis
- Un-coating in lysosome
- Transcription is mediated by endogenous virus dependent RNA polymerase (transcriptase)
- Translation to produce viral structural protein
- Synthesis of full-length transcript
- Some of the full-length transcript are encapsidate
- Synthesis of –ve sense RNA strand with capsid to form ds RNA
- Formation of inner capsid
- Morphogenesis: budding of single shelled virus into RER acquiring pseudo envelope
- Removal of pseudo envelope and replaced by outer capsid in RER
- Cell lysis and Release
- 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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