Lecture 8 Flashcards
(25 cards)
What does a virus do
Invades host cell and direct the host’s metabolic machinery to produce viral enzymes, viral proteins and copies of its nucleic acid
What is a virus 3 main points of entry
- Respiratory system
- Digestive tract
- Urogenital tract
What can innate immune responses limit
Viral infections by inhibiting viral replication
What are some viruses susceptible to
Lysozyme
How can viruses in the intestine be inactivated
By the low pH of the stomach or may be degraded by intestinal enzymes
How do host cells recognise viral nucleic acid
Via cytoplasmic and membrane sensor proteins including Toll-like receptors
When are interferons are produced and secreted
In response to viral infection
What are the 3 major classes of interferon
- IFN-a
- IFN-B
- IFN-y
What are IFN-a produced by
Virus-infected leukocytes
What is IFN-B produced by
Virus-infected fibroblast and epithelial cells
What is IFN-y derived from
Antigen stimulated T lymphocytes and NK cells
What do interferons activate
NK, macrophages, dendritic cells
What is the major function of interferons
Inhibit viral growth
Where do NK cells develop
in the bone marrow
How do NK cell kill infected cells
Using cytotoxic granules
What can NK cell make
IFN-y
What is NK cell cytotoxicity stimulated by
Type I interferons
What is the role of Ab (3)
- Neutralisation of extracellular virus
- Enhancing complement mediated killing of virus directly or cell containing virus
- Promoting cytotoxicity ans opsonisation
What do CD8 cells kill
Target cells that display peptide fragments of cytosolic pathogens both to MHC class I molecules at the surface
What do CD4 cells recognise
Antigen degraded within intracellular vesicles and displayed on the surface by MHC class II
What doe CD4 TH1 cells activate
Macrophages enabling them to destroy intracellular microorganisms, help CD8 T cells and B cells switch from IgM to particular IgG isotope
What do CD4 TH2 cells activate
B cells to produce different Ig isotopes
Where are viral proteins produced
Cytoplasm of the host cell they infect and are presented as peptides associated with MHC class I molecules for recognition by CD8 T cells
Where do CD8 T cell differentiate
In cytotoxic T cells
