Chapter 13 Flashcards
Display of new antigens (by a pathogen) that are not recognized by immune responses formed in response to previous infection
Antigenic variation
You got a virus last year. The virus mutated via replication in another host and you got the mutated virus this year. Your immunity to last year’s strain does not help protect you from this new mutant. What type of antigenic variation is this?
Antigenic drift
A pig is infected with a human virus and a bird virus at the same time. The viral genomes recombine in the pig, now you have a novel human virus that can infect the population. What type of antigenic variation is this?
Antigenic shift
Point mutations that result in minor alterations of antigenicity of a particular protein?
Antigenic drift
Reassortment of genes that results in major changes in the antigenicity of a given protein?
Antigenic shift
A state in the life cycle of some viruses during which they do not replicate and remain “hidden’ from the immune system?
Latency
Which causes more serious disease antigenic drift or antigenic shift?
Antigenic shift because in antigenic drift you still have memory T cells. An antigenic shift requires a new T and B cell response
Viral examples of latency?
Herpes virus, Varicella zoster virus
Molecules that stimulate a subset of CD4 T cells by simultaneously binding to MHC class II molecules and the TCR. These binding interactions are not specific interactions
Superantigens
Why are superantigens so bad (can cause shock)?
Soooo many T cells are activated releasing soooo many cytokines… cytokine storm… shock!
What type of cells does HIV infect and kill?
CD4 T cells
What enzyme does HIV use to convert its RNA genome into double stranded cDNA?
Reverse transcriptase
Is reverse transcriptase error prone?
Yes
What area of the world has a vast majority of AIDS cases and deaths?
Sub-Saharan Africa
Once HIV has bound to a CD4, what must it do?
Interact with a co-receptor on the host cell (a chemokine) to gain entry into the cell
