deck_21080060

Question 1

All viruses cause tissue injury the same way: By interfering with normal cellular protein synthesis and function, which eventually leads to injury and death of the cell. True or false?

Answer 1

False. Viruses can also cause damage by stimulating inflammatory responses

Question 2

There is no innate immunity to viruses. True or false?

Answer 2

False. Innate immunity to viruses comes from inhibition of infection through IFN-I and NK-cell mediated killing of infected cells.

Question 3

IFN-I inhibits viral replication in both infected and uninfected cells, by inducing an antiviral state.
True or false?

Answer 3

True

Question 4

How are NK cells able to recognize cells infected by a virus?

Answer 4

Virus mediated downregulation of MHC class I expression

or

Induction of expression of NK activating ligands

Question 5

In a viral infection, how is IFN-I produced?

Answer 5

Endossomal TLR and Cytosolic RIG-like receptors recognize Viral RNA and DNA

This leads to the activation of IRF transcription factors, which leads to interferon alfa and beta gene transcription

Question 6

In IFN-I production by viruses, what does DAI, RIG-1 and MDA-5 do?

Answer 6

DAI is a cytosolic DNA censor that can activate IFN-I

RIG-1 triggers an immune response to RNA viruses from various families

MDA-5 detects long dsRNA

Question 7

IFN receptors are expressed by infected cells, which signals other cells that they need to be destroyed. True or false?

Answer 7

False. IFN receptors are expressed by uninfected cells.

Question 8

When an IFN-I is detected by an IFN receptor on an uninfected cell, it induces expression of enzymes that block viral replication, thus putting the cell in an antiviral state.

True or false?

Answer 8

True

Question 9

Name two Type I interferons

Answer 9

IFN-alfa and IFN-beta

Question 10

If IFN-I binds to the IFN receptor of a viral infected cell, it causes the cell to begin synthesizing molecules that enhance the cell’s susceptibility to CTL-mediated killing.
True or false?

Answer 10

True

Question 11

A cell in an antiviral state has two mechanisms of protection:
- It inhibits viral protein synthesis by phosphorylation of the translation initiation factor
- Degradation of viral RNA by activation of RNAases.

True or false?

Answer 11

False. It has 3 mechanisms, with inhibition of viral gene expression and virion assembly by increasing GTPases being the one missing.

Question 12

Impairing the function of IFN-I is critical for a virus to spread. True or false?

Answer 12

True

Question 13

Antibodies work against viruses by binding to them and preventing them from entering the host cells. True or false?

Answer 13

True

Question 14

Since antibodies only work BEFORE the virus enters the cell, they are only useful for preventing initial infections. True or false?

Answer 14

False. They also help in preventing cell to cell spread.

Question 15

An antibody’s main function against a virus is preventing it from entering a cell. The fact that it may work as opsonization or complement activation is a bonus.

True or false?

Answer 15

True

Question 16

After a week of infection by a virus, what two components of the immune system can we expect to see in high ammounts?

Answer 16

Antibodies and Virus-specific CTLs

Question 17

Innate immunity and adaptive immunity both provide protection against viral infections. Mention how.

Answer 17

Innate immunity is related to the production of IFN-I that puts cells in an antiviral state.

Adaptive immunity has B cells producing antibodies that neutralize the virus

Question 18

Innate immunity and adaptive immunity both eradicate estabilished viral infections. Mention how.

Answer 18

Innate immunity uses NK cells to tell infected cells to kill themselves

Adaptive immunity has CD8 CTL cells telling infected cells to kill themselves.

Question 19

Mention three ways virus have of avoiding the immune system

Answer 19

• Inhibition of antigen presentation
• Inhibition of effector cell activation
• Production of cytokine receptors
• Inhibition of dendritic cell activation
• Inhibition of macrophage activation
• Production of of IL-10 (which fucks with macrophage activation)
• Removal of MHC I molecules from the endoplasmic reticulum

Question 20

What is antigenic drift?

Answer 20

It’s a phenomenon by which virus escape the immune system. In this, the virus accumulates so many point mutations that it eventually leads to a protein that is no longer recognized by the antibody assigned to the original protein.

Question 21

What is antigenic shift?

Answer 21

The virus of a human and the same virus but for animals “mix” after infecting the same cell which results in new surface proteins which the human antibodies don’t recognize.

Question 22

Fungi are annoying because they may act like extracellular microbes and intracellular microbes. True or false?

Answer 22

True

Question 23

Resolution of a fungal infection is usually fast because the spores produced by them are easily recognized by PRRs. True or false?

Answer 23

False. The PRRs recognize common fungal cell wall PAMPs

Question 24

The complement cascade has a protective role in fungal infections.
True or false?

Answer 24

True

Question 25

What is the major way the innate immune system fights a fungal infection?

Answer 25

Phagocytes (neutrophils and macrophages) and complements. ILCs and AMPs also take part in the defense.

Question 26

What is the major way the adaptive immune system fights an intracellular fungal infection?

Answer 26

Th1-mediated immunity

Question 27

Th1 and Th2 responses work in tandem to clear out a fungi infection. True or false?

Answer 27

False. Th2 responses are useless against fungi and can even be harmful

Question 28

What cells of the adaptive immune system are tasked with fighting extracellular fungal infections?

Answer 28

Th17 cells, since the fungi stimulate Th17 responses via DC and Macrophages

Question 29

What the fuck is a Dectin?

Answer 29

It's a common fungal carbohydrate present in their cell walls

Question 30

Problems with Th17 development can lead to increased ____________ infections.

Answer 30

Fungal

Question 31

What are the first cells to detect fungal glucans?

Answer 31

Dendritic cells and macrophages

Question 32

Walk us through what happens when a fungal glucan gets detected

Answer 32

1. A DC or a Macrophage detects the fungal glucan and releases cytokines that stimulate ILC3 2. The ILC3 produces IL-17, which recruits neutrophils and makes them produce antimicrobial peptides to protect from the infection 3. The DC also stimulates the differentiation of naive CD4 T cells into Th17 cells

Question 33

Walk us through what happens when a fungal glucan gets detected BUT MAKE IT SNAPPY

Answer 33

1. DC finds fungus and secrets IL-23 and IL-1 2. ILC3 and Th17 are recruited because of it, and produce IL-17 and IL-22 3. These cytokines recruit neutrophils and lead to the production of antimicrobial peptides

Question 34

How do fungi avoid immune recognition?

Answer 34

They need to hide Beta-glucan, and they do this by forming a capsule, or a pigment, or a mannoprotein layer, or secreting gluconases that reduce the surface of Beta-glucan

Question 35

Fungi can recruit complement regulators, block C3 convertase formation, and cleave the complement components by secreting SAPs. All this is done to.

Answer 35

Inhibit or degrade the complement system

Question 36

Fungi can manipulate phagocytic activity. True or false?

Answer 36

True

Question 37

All of the fungal cells' tricks to avoid the immune system only work before it gets phagocyted. True or false.

Answer 37

False. After being eaten, it can still manipulate phagocytic activity and even escape from the pathogen.

Question 38

What is the advantage for parasites to have such a complicated lifecycle?

Answer 38

This helps avoid the immune system by leading to changes in antigenic structure and location over time

Question 39

A protozoan is a parasite (this is not a trick this is because I know you don't know it is) Protozoans and helminthic parasites, despite both being parasites, trigger different innate immune responses. True or false?

Answer 39

True

Question 40

The main innate immune response against protozoa relies on basophils, while against helminths it relies on eosinophils. True or false?

Answer 40

False. Helminths is correct, but phagocytosis is the main response against protozoa

Question 41

Eosinophils's phagosomes are incredibly acidic, which prevents helminths from surviving phagocytosis. True or false?

Answer 41

False. Eosinophils do not do phagocytosis, and instead release granule content which includes MBP

Question 42

Why don't phagocytes just eat helminths?

Answer 42

They are too big

Question 43

Since phagocytes cannot eat helminths, they effectively counter them by secreting microbicidal substances. True or false?

Answer 43

False. Everything is true, except most helminths are actually resistant to these substances due to BEING BORN WITH THICK SKIN.

Question 44

Protozoa are intracellular parasites (probably) Knowing this, what do you expect to be the main adaptive immune response against them?

Answer 44

Cell-mediated immunity activated by IFN-gamma produced by Th1 cells, which activates macrophages to destroy intracellular parasites.

Question 45

What makes IFN-gamma so good against protozoal infections?

Answer 45

- Toxic to many protozoans - Stimulates IL-12 production (by macrophages and DCs) which leads to more IFN-gamma - iNOS expression in macrophages - Upregulates enzymes for phagosome maturation

Question 46

What cytokines are produced by Th2 cells in helminthic infections?

Answer 46

IL-4, which stimulates B cells to produce antibodies like IgE that bind to mast cells and leads to their degranulation Il-4 and IL-13, which increase intestinal mucus secretion and peristalsis which leads to helminth expulsion IL-5, which activates eosinophils.

Question 47

Help for antibody production during an helminth production may be given by Tfh cells, which produce Th2 cytokines. Why is this weird?

Answer 47

Because the cells that the Tfh cells are helping ARE Th2 cells

Question 48

One of the way helminths avoid being destroyed by the immune system is by preventing phagocytosis. True or false?

Answer 48

False. Helminths aren't destroyed by phagocytosis

Question 49

A parasite leads to the production of different antibodies depending on what stage of their life they are. True or false?

Answer 49

True

Question 50

Antigenic variation in helminths comes solely from stage-specific change in Ag expression. True or false?

Answer 50

False. They can change how a major surface Ag is expressed.

Question 51

What are the three major ways parasites can inhibit host immune response?

Answer 51

- Parasites can become resistant to immune effector mechanisms during residence in vertebrate hosts - Parasites may conceal themselves from the immune system by either living inside host cells or by developing cysts resistant to immune effectors - Parasites can directly inhibit host immune responses by T cell anergy, regulating regulatory T cells, and production of immunosuppressive cytokines.

Question 52

Resistance to a disease is only provided by the adaptive immune system. True or false.

Answer 52

False. Both immune systems contribute to it

Question 53

Disease tolerance limits the negative impact of infection on the host, but does not affect pathogen amount. True or false?

Answer 53

True

Question 54

What would happen if I had max tolerance for a disease but 0 resistance to it?

Answer 54

My cells would be made of steel; I would suffer 0 tissue damage from disease, but at the same time, I'd have 0 ways of driving out the disease.

Question 55

What are three mechanisms that mediate disease tolerance?

Answer 55

Tissue protection and repair, as a way to limit damage to tissues during infection. Host metabolic rewiring so that organs/tissues can continue to function under the stress of infection Balancing immune activation so that the response itself doesn't cause disproportionate damage.