L20-Cytotoxic killing of viruses

Question 1

What does the word prodromal describe?

Answer 1

The first symptoms of an infection

Question 2

What is the cause of ‘flu like symptoms’ expreienced with many viruses?

Answer 2

Interferon induced responces which are the innate immune system signalling through interferons. This limits the pathogen and may clear the infection, the interferons also induce the secondary antigen-specific responses.

Question 3

What happens after the infection is over to the interferons?

Answer 3

The PRRs have to be switched off and the IFN response inhibited.

Question 4

how are the majority of viruses killed by the immune system?

Answer 4

Through cytotoxic T cells recognising cells MHC class I molecules

Question 5

How do natural killer cells recognise virus infected cells?

Answer 5

Viruses often inhibit the presentation of peptides in the infected cell by downregulating MHC I so NK cells can recognise a lack of MHC I molecules and kill the cell.

Question 6

How do cytotoxic CD8 cells trigger cell death of cells presenting peptide on their MHC class I molecule

Answer 6

They can release perforin and other cytotoxins that punch holes in the cell membrane.
FAS ligand protein binds to FAS on the cell and induces apoptosis.

Question 7

What is Antibody-directed cell cytotoxicity (ADCC)

Answer 7

It is when NK cells Fc receptors recognise the Fc portion on bound antigens allowing killing of that infected cell

Question 8

How can antibodies prevent viruses from reproducing?

Answer 8

By binding to docking antigens and preventing the virus from binding to cells