Immune Response to Viruses Flashcards
What is the response time of adaptive immunity?
Slow (days)
What is the specificity of the adaptive immune response?
Highly specific
What is the memory of the adaptive immune response?
Has memory
What is adaptive immunity essential in?
The fight against intracellular pathogens such as viruses
What does adaptive immunity best deal with?
Most stages of microbial pathogenesis and can have some effect on early stages of replication (toxicity, invasiveness, tissue damage, disease)
What happens first in antigen recognition?
Virus is phagocytosed and destroyed by an APC
What is the result of the virus being phagocytosed and destroyed by an APC?
Viral peptides (from the capsid)
What do viral peptides do?
Bind to the MHC-ll
What do APC’s have?
MHC-l and MHC-ll
What happens after the viral peptides bind to the MHC-ll?
APC/DC leaves the site and moves to the lymph nodes
What happens before encounter with antigens?
Mature lymphocytes with receptors for many antigens develop
What happens in clonal selection?
Viral peptide (antigen) presented on MHC is used like a key by the dendritic cell, hunting around until it finds the matching lock
What happens after the key find the lock?
Expansion of T and B lymphocytes expressing the same antigen receptor
What do T cells differentiate into?
Cytotoxic CD8 cells, helper CD4 cells and also memory cells
What is happening in the mucosa?
As soon as a virus enters and starts replicating, MHC l takes part of its capsid and presents it to T cells which causes cell death
What does MHC ll stimulate?
CD4 T cells
What does MHC I stimulate?
CD8 T cells
Where are cytokines produced?
By CD4 T cells
What do cytokines help?
CD8 T cells become activated
What do cytotoxic T cells synthesise?
Special proteins that specifically kill the virally infected host cell
What are cytotoxic T cells full of?
Granules (perforin and granzyme) which cause apoptosis when released
What does the infected host cell do?
Lets the cytotoxic T cell know it is infected by presenting the viral antigen on the cell surface using MHC-l
What do B cells differentiate into?
Memory cells and effector (mature and plasma) cells
What must happen for the plasma cells to develop from B cells?
- Unprocessed antigen needs to attach to the B cell receptor (BCR)
- Helper T cell to attach to processed antigens presented by the APC MHC-ll (this causes the cytokines to be released from the helper cell)
How is complement activated by adaptive immunity?
Through the classical pathway
What happens during primary exposure to A?
A small amount of IgM produced
What happens during secondary response to A?
More rapid and larger production of IgG
What happens when primary exposure to B occurs at the same time as secondary exposure to A?
Small amount of IgM produced (symptoms still occur)
What do vaccines do?
Help prime the immune response for future exposure to the viral pathogen
What are the components of vaccines?
Antigen and adjuvant
What is antigen?
The specific molecule that the immune system may recognise - made using heat killed, attenuated (repeated culture/passage) or recombination viral proteins
How does attenuation occur?
Through passage through non-human cells
What is adjuvant?
Helps to enhance the immune response against the antigen
