Immunology and Infectious Disease Flashcards
What is the difference between infection, disease, and pathogens?
What is a virulence factor?
A virulence factor is a quality that enhances the ability of a microbe to cause disease.
What are the 3 main ways that microbes cause disease?
What is the natural history of disease?
Key - progression in ABSENCE of treatment
Bacteria
- Prokaryotes or eukaryotes?
- Unique feature of bacterial cell structure?
- Uni or multi cellular?
- Virulence factors?
- Where do they grow wrt host cells?
- What is the function of the capsule?
Capsule –> offers protection from innate immunity b/c makes organism “slippery” (harder for macrophages to phagocytose) and also helps prevent deposition of complement proteins to initiate the complement cascade.
The principal mechanisms of innate immunity to extracellular bacteria are […] , […], and […].
Complement activation
Phagocytosis
Inflammatory response
Describe the generalized process of how the innate immune system produces phagocytosis and inflammation in response to extracellular bacteria.
The principal mechanism of adaptive immunity to extracellular bacteria is […] and […]
Antibodies
Th17 Response
What are the various ways in which antibodies, produced by B cells, lead to immunity against bacteria?
- Neutralization
- Opsonization
- Complement activation
- Inflammation
- Phagocytosis
- Lysis
What is the Th17 response?
Bacteria in the body is phagocytosed by dendritic cell (APC), presents part of digested microbe on MHC class 2 receptor on cell surface. APC presents signal 1 (MHC2) and signal 2 (B7) to CD4+ (mature but naiive T cell). APC secretes cytokines to induce the CD4+ T cell to become a Th17 cell. Th17 cell then secretes IL-17, which promotes neutrophil response, inflammation and antimicrobial peptides.
Antibodies against bacteria are directed at […] and […].
Cell wall antigens
Toxins
Proteins are T-[…] antigens while the polysaccharide capsule is a T-[…] antigen.
Dependent
Independent
What is the difference between t-dependent and t-independent activation of B-cells?
T-dependent
- Required for response to protein component of microbes
- B cell binds to protein in its native conformation, phagocytoses protein and expresses parts of protein on its surface via MHC class 2
- Binding of signal 1 (antigen on MHC2) and signal 2 (CD40 on B cell) activates the T cell and causes it to secrete cytokines that then act on the B cell causing the B cell to undergo expression of AID (activation induced cytidine deaminase) which allows for the class switching of the B-cells antibodies from IgM to IgG, IgA and IgE (which one is produced depends on the cytokine profile released from T cell) and then affinity maturation of those antibodies.
T-independent
- B cell expresses membrane IgM which binds to antigens other than proteins (polysaccharide, lipid, etc.)
- If enough of this antigen binds to the B cells IgM receptors, then it can induce the B cell to become a plasma cell that secretes plasma IgM (5 IgMs together in 1 massive antibody)
- These do not undergo affinity maturation so they are low affinity and plasma cells produced by this method are short lived
Viruses are obligate […] pathogens.
Intracellular.
The principal mechanism of innate immunity to viruses are […] and […]
Interferons
Natural killer response
Describe the innate immunity response to viruses.
Note: the activation of the PRR pathway and the NK cells are NOT the same mechanism. PRRs are on cells that are infected with the virus, NK cells are CD8+ T cells that interact with cells infected with virus and kill them via the mechanisms described here.
The principal mechanism of adaptive immunity to virus is […] which releases […] and primes […].
Th1 response
INF gamma
CD8+ cytotoxic t lymphocytes
Describe the adaptive immune response to viruses.
Describe how the immune system responses to intracellular pathogens that ARE NOT viruses (i.e. certain kinds of bacteria, fungi and protozoa).
The adaptive immune response to protozoa is […] while the adaptive immune response to helminths is […]
Th1
Th2
Protozoa are […]cellular while helminths are […]cellular
Intra
Extra
Describe the adaptive immune response to helminths.
Why do many parasitic infections become chronic?
Due to weak innate immunity response and ability of parasites to evade or resist elimination by adaptive immune response
