WEEK 1: Antiviral immunity Flashcards
what is a virus?
An infectious, obligate intracellular parasite comprising genetic material (DNA or RNA) surrounded by a protein coat and/or an envelope derived from a host cell membrane
what are the stages of the virus replication cycle? (6)
attachment, penetration, uncoating, replication, assembly, virion release
how do ‘hit and run’ viruses evade immune system?
they destroy the cells of the host in which they are multiplying. highly infectious and rarely persist.
how do ‘hit and stay’ viruses evade immune system?
they evade immune control by blockade of antigen presentation, cytokine escape, evasion of NK cells,escape from apoptosis.
what are the 3 levels of defence against viruses?
- physical barriers
- innate immune system
- adaptive immune system
give examples of physical barriers
skin, mucous secretions, rapidly regenerating surfaces, vomiting, coughing, lysozyme in tear fluid, stomach acid
give examples of innate immune system
cytokines (interferons), complement proteins, phagocytosis (macrophages/neutrophils), NK cells, mast cells
give examples of the adaptive immune system
B lymphocytes and antibodies, T lymphocytes (Th cells, Tc cells)
what are interferons?
secreted glycoproteins that are produced by cells in response to a virus infection and induce an antivrial state in cells with IFN receptors.
what are the 3 groups of IFNs?
type 1, 2, and 3
which type of IFN are IFN-α and IFN-β?
type 1
which cells produce IFN-α and IFN-β?
most, if not all, nucleated cells
which cells produce IFN-γ?
T cells, NK cells
what do NK cells do?
target and kill infected, transformed and stressed cells
how are NK cells activated?
NK cells are activated in response to interferons or macrophage-derived cytokines
