Molecular Biology of Orthomyxoviridae

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Genome & Virion                  Replication, Transcription & Translation                      Evolution

Key Features of Influenza Biology

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  • The Influenza genome has 7-8 segments, depending on the strain. Influenza types A and B have 8 segments while Influenza C has 7. 
  • The multiple segments allow for reassortment to occur, which leads to genetic diversity and can give rise to strains that can infect humans with no immunity to this new strain. 
  • Both transcription and replication take place in the nucleus. 
  • Viral transcription requires "cap stealing" where a viral enzyme cleaves the cap of host mRNA that is used as a primer.
  • Gene expression involves many processes, including alternative start codons, overlapping reading frames, splicing, and nested reading frames.
  • Influenza viruses enter the cell through receptor mediated uptake
  • Influenza virus replication generates defective interfering particles in the process.