Immunity To Pathogens Virus, Helminth And Protozoa Flashcards
Examples of indirect damage from pathogens
Examples are:
-Immune complexes
- Anti-host antibodies
- Cell-mediated immunity
Examples of direct damage from pathogens
Exotoxin production
Endotoxins
Direct cytopathic effects form CD 8 cells
What is the vast majority of new diseases caused by?
Zoonotic diseases
Zoonotic viral infections
Infections from animals -> humans
- can be dangerous since some viral infections can experience antigenic shifts through zoonotic vectors (i.e influenza)
Common strains of influenza
North America swine flu
North America avian flu
Human influenza
Asian swine flu
- all can causes PEs which is the leasing cause of death from flu*
- flu strains can combine with each other*
Toll-like receptors
Primarily expressed by innate cells that recognize various PAMPs
- can be extra or intracellular
When bound to pathogen antigens, stimulates 2 major transcription factors
- NF-kB (promotes inflammation)
- IRF-3 (promotes antiviral IFNs and stimulates NK cells)
Granzymes
Serine esterases that are released into infected cells that have been induced by perforin
Activates caspase C cascade and initiates apoptosis
Viral innate immune response
Viral dsRNA and DNA trigger TLR activation
TLRs lead to transcription factors Nf-kB and IRF-3
The IRF-3 then transcribe type 1 IFNs (a & b) and IFN-y
IFN-y further activates NK cells and increasing ability to kill infected cells
The type 1 IFNs induce the antiviral state
Antiviral state includes activates of RNase which inhibits transcription of viral genes
Why does adaptive immunity not work well against viral targets?
Viral pathogens mutate which makes it difficult to make antibodies for it.
CTLs and NK cells are the best killers of viral pathogens
Viral adaptive immune response
Viruses infect APCs and their proteins in the cytosol are processed for MHC by intrinsic pathway
Infected cells present with class 1 MHC and activation of CD 8 T cells
CD 8 T cells use FAS/FASL, perforin/Granzymes and TNF/LT
CD4 T cells than begin secreting large amounts of antibodies to further activate the CD8 T cells and NK cells
Type 1 IFNs from virally infected cells also increase expression of class 1 MHC and production of antibodies by B cells
Viral vaccines
Always killed virus
Develops a humoral response that is quadrivalent and usually target areas where the virus CANT mutate
Can be used in the new egg-free version (not incubated in eggs)
- used for people with egg allergies but isnt really that much more efficacy
Can use nasal spray also but NEVER in immunocompromised patients (live vaccine)
Helminth immunity
Exclusively adaptive, innate doesn’t work against it
Most digest mucosal tissue or blood and produce excretory-secretory proteins
Uses both humoral and cell-mediated adaptive immune responses via a skew towards TH2 response
Why is innate ineffective against helminths?
Helminths dont have PAMPs and some of the ES (Excretory-secretory) proteins ligate TLRs to inhibit innate responses
No TLRs = cant up-regulate MHC or produce cytokines for Cytotoxic T-cells
Adaptive immunity response to helminths
Parasites trigger IgE class switching
This leads to mast cell degranulation and tissue inflammation
Eosinophils are called in during the resulting inflammation which is typical of a type 1 hypersensitivity response
This makes the mucosa less appealing to parasites which causes them to usually detach from the mucosa
T cells are then also called in during inflammation response to the gut causing B cells to secrete IgE which serves as an opsonin for the parasite.
Protozoa adaptive immunity response
Parasitized cells present antigens to CD8 T cells
CD8 T cells respond by secreting IL-2 and IFN-y
IFN-y then activates parasitized cells to enhance their ability to kill intracellular parasites via ROS and phagocytes
- also increases NK-cell activity
Also, CD4 T cells induce B cells to secrete IgE after class switching
