Viral Immunity Flashcards
Intrinsic immunity
natural barriers
skin
mucous
tears
low pH
absence of appropriate virus receptors
Physical and anatomical barriers
Intracellular barriers that block replication
Innate Immune system
First line of immune defense against a virus
Interferons
inflammatory cytokines
phagocytic cells - macrophages and monocytes
NK cells
RNAi
Acquired / Adaptive immune system
Tailored to the pathogen
needed if the pathogen gets past the innate immune system
Specific to the pathogen
Host responses
Innate Immune System
- No prior exposure to virus is needed for the innate immune system to function
- Compontents include:
- cytokines
- Pattern recognition
- sentinel cells
- dendritic cells, NK cells, Macrophages
- If this system cannot get rid of the infection the adaptive immune system will take over and make B and T cells
Pattern-recogintion receptor
molecules that recognize PAMPs
PAMPs
pathogen associated molecular patterns
Toll-like receptors
Genes needed for dorsa-ventral axis development
found thta they are important in fly immunity in Drosophila
These are transmembrane proteins
Pattern recognition receptor molecules that recognize
PAMPs
self from pathogen
Host Responses
Innate immune system
Macrophages
engulfs the virus infected cell by phagocytosis
Intracellular pattern recognition receptors sense the presence of viral genetic material
Immune signaling is initiated to produce type 1 interferon and pro-inflammatory cytokines
Type 1 interferon sitimulates the transcription of antiviral interferon stimulated genes
Host response
innate immune system
Natural Killer (NK) cells
recognize self MHC calss 1 and does not kill the cell
Host Responses
Innate immune sytstem
Immune cytokines
Virus-infected cell produces Type 1 IFN, which induces a virus-resistant state in surrounding cells
- shut down protein translations in infected cells
- limit the production of viral proteins
- Inhibit cell division
- limit the spread of viruses via cell division
- Degradation of host mRNA shuts down the intracellular biochemical machinery required for viral propagation
Host responses
Timeline for host response
Host Responses:
Adaptive / Acquired immuntiy
Tailored to the pathogen
Needed if the pathogen gets past the innate immune system
Specific to the pathogen
Trojan Horse
some viruses infect dendritic cells and carry viruses into the lymph nodes
Dendritic cells pick up the dead cell and present to the lymph node - dentritic cells are antigen presenting cells
t lymphocytes
- Cell mediated response
- needed to clear most viral infections
- most viral infections stimulate the Th1 response
- Naive T cells
- split into one of the two lines
- CD4 helper T lymphocytes
- make cytokines that help with B cell maturation, activate marcrophages and infammation
- CD8 cytotoxic T lymphocytes
- cytotoxic T cells lyse the virus infected cells
- CD4 helper T lymphocytes
- split into one of the two lines
Host responses
Adaptive immunity
Th1 or Th2 response
cell-mediated response - needed to clear most viral infections
Naive T helper cells become either Th1 or Th2
Th1 - CTLs are activaed by cytokines and clears many viral infections
Th2 - activate B cells with cytokines not as good for clearing viral infections
Class 1 MHC pathway
lead to killing infected cells
ENDOGENOUS ANTIGENS - antigens generated within a virus-infected cell
can occur in almost any cell in the body
Class 2 MHC pathway
EXOGENOUS ANTIGENS - antigens made outside the cell
Humoral response:
Activate the B cells
- B cells are presented with viral antigens by antigen presenting cells
- Clones of B cells are selected and amplified to secret antibodies
- Certain clones of B cells become plasma cells
- Antibodies can be made for homologous infections in the future
Antibodies
variable regions bind to the antigen
the constant region does not vary much within a certain species
Neutralize, opsonize, complement-mediated lysis
