orthomyxoviridae and paramyxoviridae

• What is the size range of the viruses in the Orthomyxoviridae family?

  80-120 nm
• What type of RNA do Orthomyxoviridae viruses have?

  Segmented linear ssRNA (-)
• What is the symmetry of Orthomyxoviridae viruses?

  Helical symmetry
• How does the lipid envelope of Orthomyxoviridae viruses affect their inactivation?

  It is easily inactivated by disinfectants and detergents
• How long are Orthomyxoviridae viruses infectious at body temperature?

  About 1 week
• How long can Orthomyxoviridae viruses remain infectious at 0 °C?

  Over 30 days
• What are the six genera of the Orthomyxoviridae family?

  • Influenzavirus A
  • Influenzavirus B
  • Influenzavirus C
  • Isavirus
  • Thogotovirus
  • Quaranjavirus
• What is the family name of the viruses that include influenza viruses?

  Orthomyxoviridae
• How many proteins does the segmented negative-sense RNA of Orthomyxoviridae encode?

  11 proteins
• What are the two best-characterized proteins of Orthomyxoviridae viruses?

  Hemagglutinin and neuraminidase
• What role does hemagglutinin play in the influenza virus?

  It mediates binding to target cells
• What is the function of neuraminidase in the influenza virus life cycle?

  It helps release progeny virus from cells
• Why are hemagglutinin and neuraminidase considered antigens?

  They are recognized by antibodies
• How are different serotypes of influenza A viruses classified?

  By antibody responses to hemagglutinin and neuraminidase
• How is the influenza virus transmitted?

  By coughs, sneezes, and bodily fluids
• What is the process by which the influenza virus enters a host cell?

  Endocytosis
• What happens to the influenza virus in the acidic endosome?

  Hemagglutinin fuses the viral envelope
• What is formed when viral proteins and vRNA are transported into the nucleus?

  A complex for transcribing cRNA
• What happens to cRNA after it is transcribed?

  It can be exported or remain in the nucleus
• How are newly synthesized viral proteins processed?

  They are secreted or transported back to the nucleus
• How does the mature influenza virus exit the host cell?

  By budding off in a phospholipid membrane
• What happens to the host cell after the release of the influenza virus?

  The host cell dies
• What is the mutation rate of the influenza virus due to RNA proofreading enzymes?

  One error every 10,000 nucleotides
• What is antigenic drift in the influenza virus?

  It refers to mutations in the viral genome
• What is antigenic shift in the influenza virus?

  It results from reassortment of genome segments
• What is the incubation period for influenza?

  1-2 days
• What are common symptoms of influenza?

  High fever, runny nose, sore throat
• What are potential complications of influenza?

  Viral pneumonia and secondary bacterial pneumonia
• How long does short-term immunity last after influenza infection?

  1-3 years
• What are the laboratory diagnosis methods for influenza?

  • Haemagglutination inhibition
  • Immunofluorescence
  • ELISA
• What is the purpose of the haemagglutination inhibition test?

  To detect antibodies in serum samples
• What is the procedure for the haemagglutination test?

  Adding viral suspension to serum and RBCs
• What indicates a positive result in the haemagglutination inhibition test?

  A button of unagglutinated RBCs
• What is the recommended vaccine for influenza?

  A vaccine recommended by the WHO
• Why does the influenza vaccine require annual updates?

  Due to the high mutation rate of the virus
• What types of strains does the influenza vaccine contain?

  Three or four influenza virus strains
• How can the influenza vaccine be administered?

  As an injection or nasal spray
• What antiviral drugs are used for influenza treatment?

  Amantadine, rimantadine, zanamivir, oseltamivir
• What is the size range of viruses in the Paramyxoviridae family?

  100-300 nm
• What type of RNA do Paramyxoviridae viruses have?

  Not-segmented linear ssRNA (-)