Microbio Week 10 - Viral Immunology & Viral Vaccines (Exam 3) Flashcards
What are innate defenses specific to?
General class of the pathogen
T/F: Innate defenses are specific to the pathogen itself
FALSE, innate defenses are specific to the general class of the pathogen
What defenses respond first to initial exposures?
Innate
What do innate defenses do to the pathogen?
Slow or stop it
What defenses respond to secondary exposures?
Adaptive
What parts of the adaptive response act fast to prevent disease when encountered with a secondary exposure?
Neutralizing ABs and CTLs
What type of barriers can stop a microbe from infecting a person?
Physical barriers
Name 5 examples of physical barriers that can stop a microbe from infecting a person
Skin
Coughing
Sneezing
Mucus
Stomach acidity
____________ compounds can also act on viruses to prevent infection
Antimicrobial
If a virus can circumvent the physical barriers and infect a cell, what type of cell is triggered?
Type I interferon
What do Type I interferons tell your body?
That an infection is happening
What do pattern recognition receptors recognize in an infected cell? What do they stimulate?
Recognize viral RNA + DNA
Stimulate Type I interferons
What do interferons induce in infected cells and neighboring cells?
Wide variety of genes
What do interferons help guide?
Immune response
What do interferons activate?
Antiviral proteins
What response have many viruses figured out ways to reduce?
Type I interferon response
What type of cells are important in viral infections?
NK cells
What do NK cells kill? What does this stop?
Infected cells, stopping the viral spread
Note from lecture: NK cells also kill cells without MHC I
What are NK cells most well-known for recognizing?
Cells that down-regulate their MHC I
Why do many viruses down-regulate MHC I?
To escape CTL killing
What 2 cells are essential in bridging the innate and adaptive immune responses?
Macrophages and dendritic cells
Which specific type of dendritic cell makes large amounts of Type I interferons when there is a viral infection?
Plasmacytoid dendritic cell
Why are plasmacytoid dendritic cells able to make large amounts of Type I interferons when there is a viral infection?
They sense viral infections without being actively infected
Can viruses stop interferon production in plasmacytoid dendritic cells?
NO, because plasmacytoid dendritic cells are able to produce Type I interferons without an active infection
What are the 2 critical parts of the adaptive immune response to viral infections?
Neutralizing ABs and CTLs
What do neutralizing ABs bind to? What does this prevent?
Surface of the virus, prevents virus from infecting a cell
What do viral antigens encountered in the mucosa primarily produce?
Dimeric IgA
Which antibody is produced in large quantities in mucosal surfaces, gut, and upper/lower respiratory tract?
Dimeric IgA
Viruses with a vimeric stage (virus in the blood) primarily produce which type of antibody?
IgG
Why are CTLs critical for viral infections?
They kill infected cells and keep chronic viral infections in check
What are the 4 ways viruses can subvert the immune system?
- Escape neutralizing ABs by antigenic drift
- Block Type I interferon response
- Down-regulate MHC I to prevent getting killed by CTLs
- Kill immune cells
If you encounter the same strain of a virus, you are generally protected from reinfection due to what 2 things?
Long-lived plasma cells and secreted ABs
Which 2 locations are neutralizing ABs present before re-encountering a virus?
Mucosa and blood
Neutralizing ABs already present in mucosa and blood bind directly to the virus and prevent re-infection. What can happen after this?
Another round of affinity maturation, so you end up for even more ABs against this virus
What are the 3 possibilities when you encounter a different/new strain of a virus for the first time?
- Cross-protection
- Partial cross-protection
- No cross-protection
New strain is recognized with good affinity by ABs from a previous strain, resulting in no infection or sickness
Cross-protection