Section 6 Flashcards
What are some general way a pathogen can avoid the innate immune system?
- Avoid phagocytic action
- Interfering with ciliary action
- Interfering with complement alternative pathway
- Producing iron binding molecules
- Blocking interferons
How can a pathogen avoid phagocytic action?
- Release toxins
- Prevent opsonization
- Prevent contact
- Inhibit phagolysosome fusion
- Escape in cytoplasm
- Release chemicals to resist killing once in phagocyte
How can a pathogen prevent opsonization?
Since antibodies tag a pathogen using the light chains and phagocytes identify the pathogen by binding to the heavy chain, if a pathogen can produce a protein that binds to the heavy chain of the antibody, opsonization will be prevented
How can a pathogen prevent contact?
Capsules
What is an example of a pathogen that interferes with ciliary action?
Bordetella pertussis
What does a pathogen with a capsule mean for the complement alternative pathway?
It will prevent either C activation or access to the fixed C3b
____ is resistant to MAC complex formation. How?
- Bacterial membrane
- By shedding the part of the membrane that will attach to the other proteins in the MAC
Which part of bacteria activates the complement pathway?
Surface molecules
What iron-binding molecules can pathogens produce?
Transferrin
What is an example of a pathogen that produces iron-binding molecules?
Neisseria
Why is it more challenging to avoid the adaptive immune response?
- B cells can recognize any shape
- Macrophages have intracellular microbes
____ are very good at avoiding immune defences
Viruses
What can lead to better survival in a host?
No extensive tissue damage
What does “hit and run” mean?
Microbe invades, multiplies, and sheds before adaptive immune system is activated
How can a pathogen conceal antigens?
- Hide in host cells
- Hide at sites not exposed to circulating lymphocytes
- Molecular mimicry
- Cover microbial surface with host molecules
What type of pathogens commonly hide in host cells?
Viruses
What are examples of sites in the body that are not exposed to circulating lymphocytes?
- CNS
- Joints
- Testes
- Placenta
What is an example of an infection that hides at a site not exposed to circulating lymphocytes?
Warts
What is difficult about an infection that hides at a site not exposed to circulating lymphocytes?
Immune cells can’t reach it, so in order to get rid of the infection, you must kill the host cells that it is present in
What is released upon inflammatory response activation?
Lymphocytes, antibodies, and C
What is retroviral RNA?
RNA viruses that can change their RNA to DNA once in a host cell
What is molecular mimicry?
When a pathogen that infects someone has an antigen that is very similar to self-antigens
Who does molecular mimicry benefit and who does it damage?
No benefit; damages host
What is an example of a pathogen that covers microbial surface with host molecules?
- Staphylococcus aureus - produces protein A that has a binding site for the Fc region of antibodies
- If a phagocyte can recognize the free Fc region it will not initiate phagocytosis
