Viruses

• Influenza originally classed as what?

  myxoviridae
• What main types of influenza exist?

  A,B and C
• What is a Capsid?

  Protective coat around the viruses genetic material
• What actually is a myxovirus though?

  A virus that binds to sialic acid residues in mucoproteins. THINK MYXO=MUCUS
• Influenza is an RNA virus but what type of RNA virus?

  Single- Stranded
• Influenza has 8 genome segments coding for how many viral proteins.

  10
• Haemagglutinin a protein on influenzas membrane surface and made up of 549 amino acid is observed to do what?

  1. Agglutinate RBC`S
  2. Binds to Salic acid residue on hosts membranes
  3. Limited to the URT
• What does Hemagglutinin undergo before binding to the host?

  Post translation cleavage by trypsin (only found in the URT) forming 2 peptides (HA1 & HA2).
• Haemagglutinin and Neuraminidase act antagonistically meaning?

  They act in opposition to one another as Neuraminidase can reverse HA`s bonding to the Salic acid.
• Neuraminidase is a Type 2 integral membrane protein with 3 regions what is it`s function?

  To release a new virion from a host cell or help free a virion from capture by the hosts mucoproteins.
• There are 2 ways Antigenic changes occur name and explain how they work

  Drift= Slow and continuous change

  Shift= Sudden and Sporadic change
• Why does Protective immunity not last a lifetime?

  Frequent antigenic changes caused by mutations changing amino acid sequences.
• What is barrier nursing?

  Physically seperating the infected and non infected.
• Viruses cannot survive on their own without a host what life cycle is this?

  Obligate intracellular life cycle
• Why do viruses need a host?

  to replicate
• Repeat units of viruses are named?

  Capsomers (polymers of capsids) they are very capable of self assembly and efficient coders.
• 2 main types of nucleocapsids are?

  Helical and icosahedral.
• Viruses have small genomes true or false?

  True