Immunity to viruses Flashcards
What is tropism of virus
Which cell the virus is going to infect because each cell type has different attachment proteins on its surface
different ways in which virus can leave cell
- Budding which takes the plasma membrane
- Cytolysis (bursts host cell)
Where in the infective life cycle of a virus can we intervene to stop infection
- Free virus particles where they are not inside the host cell yet. We can stop them attaching onto host cell membrane
- Stop virus replicating inside host cell
How can you stop free virus stop binding
antibody that binds to surface of virus which may stop the binding.
However, if it does not directly stop the binding, it can indirectly stop the binding
How can antibodies indirectly stop the binding of the virus to the host cell
Activates intra-cellular degradation via TRIM21
How can antibodies use TRIM21
- Virus binds to host cell and enters it
- The virus still has the antibody bound do it
- Inside the cell, TRIM21 is bound to the Fc region of the antibody which is bound to the virus
- This triggers ubiquitination of the whole antigen-antibody complex
- activates proteasome which allows proteasome degradation
Once antibodies are bound to antigens, what else can they trigger?
-Why is this beneficial and what can this do?
Complement system of proteins
-Complements can form membrane attack complexes which can damage enveloped viruses (those which budded using the membrane f it’s host cell to make its own membrane)
What can the C3b complement protein do
Opsonise surface of microbe which enhances the interaction between microbe and phagocyte which also enhances the interaction with phagocytes
What is another anti-viral effect of antibodies
Antibody bound to infected cell to cause antibody-dependent cellular cytotoxicity
What is antigenic drift and what is It caused by
Slight changes in antigenic structure of virus
-caused by slight changes in genome i.e. there may be a base mutation which may change only one amino acid which may slightly change the structure
What is antigenic shift
Sudden/rapid change in the antigens because of an exchange of information between two different strains of a virus (can occur when two different viruses is simultaneously infecting the same animal)
What are the defensive substances used in intra-cellular cytosolic infection
Interferon proteins
Natural killer cells
Cytosolic T cells
What is the virus titer
How much you can dilute virus particles in body where you can no longer detect them
what are the first main things to happen in the innate response
- production of interferon alpha and beta
- Natural killer cell mediated killing of infected cells
