L20-Cytotoxic killing of viruses Flashcards
What does the word prodromal describe?
The first symptoms of an infection
What is the cause of ‘flu like symptoms’ expreienced with many viruses?
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.
What happens after the infection is over to the interferons?
The PRRs have to be switched off and the IFN response inhibited.
how are the majority of viruses killed by the immune system?
Through cytotoxic T cells recognising cells MHC class I molecules
How do natural killer cells recognise virus infected cells?
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.
How do cytotoxic CD8 cells trigger cell death of cells presenting peptide on their MHC class I molecule
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.
What is Antibody-directed cell cytotoxicity (ADCC)
It is when NK cells Fc receptors recognise the Fc portion on bound antigens allowing killing of that infected cell
How can antibodies prevent viruses from reproducing?
By binding to docking antigens and preventing the virus from binding to cells
