Chapter 4

Question 1

Restriction Factors

Answer 1

anti-viral proteins that are produced in the host and counteract or ‘restrict’ viral replication.

Question 2

Innate Immunity

Answer 2

Native/non-specific immunity. Has no memory response. Cytokines, phagocytes, NK cells, TLRs, and complement.

Question 3

Adaptive Immunity

Answer 3

Acquired/specific immunity. Has memory. Mediated by T cells and B cells.

Question 4

Cellular components

Answer 4

Macrophages, Neutrophils, NK cells

Question 5

Cytokines

Answer 5

Small proteins that are secreted by cells to mediate immune functions of other cells

Question 6

Antiviral Cytokines

Answer 6

IFN-α and IFN-β are the type I interferon’s that are primarily involved in anti-viral innate immunity.

Question 7

Other Innate Cytokines

Answer 7

TNF-α stimulates the activity of macrophages and neutrophils. IL-1 and IL-6 are also pro-inflammatory cytokines. They in turn stimulate adaptive immunity cytokines like INF- γ and IL-12.

Question 8

Complement

Answer 8

Small proteins that are present in the serum and help to destroy infected cells.

Question 9

Phagocytes

Answer 9

Include several types of white blood cells such as dendritic cells, macrophages, neutrophils and natural killer cells [NK cells]. They seek and destroy invaders. Some also destroy damaged body cells.

Question 10

Antigen Presenting Cells

Answer 10

Include dendritic cells, macrophages and monocytes. B cells can also present antigen.

Question 11

NK Cells

Answer 11

Natural killer cells. Induce cell death by apoptosis.

Question 12

Complement Pathway

Answer 12

If activated, complement binds to the Fc regions, recruits the membrane attack complex (MAC) to lyse the infected cells e.g HSV

Question 13

CMV

Answer 13

Produces an MHC-1 homolog that engages the NK cell inhibitory receptor to generate a DON’T KILL signal.

Question 14

HIV

Answer 14

Nef protein - upregulates the inhibitory signal to NK cells

Question 15

HSV

Answer 15

produce envelope glycoproteins that bind Fc non-spedifically. Therefore it prevents ADCC as well as complement mediated lysis of free virus.

Question 16

Classical

Answer 16

Requires Antibody

Question 17

Alternative

Answer 17

Does not require antibody. C3 is spontaneously cleaved.

Question 18

Lectin

Answer 18

Requires mannose binding protein.

Question 19

Complement Fixation

Answer 19

Binding of C3b to protein and carbohydrates on the viral surface. Then it recruits the MAC

Question 20

Acute Phase Proteins

Answer 20

Indicate inflammation is occuring in the body.

Question 21

PRRs

Answer 21

Pathogen recognition receptors on cells. (TLRs)

Question 22

PAMPs

Answer 22

Pathogen associated molecular patterns (DsRNA, CpG, DNA, LPS)

Question 23

Interferons

Answer 23

Proteins that inhibit viral replication

Question 24

PKR

Answer 24

Transcription factor

Question 25

Viroceptors

Answer 25

Viruses can secrete analogs of cytokine receptors or regulatory factors to bind up secreted cytokines or inhibit secretion.

Question 26

Virokines

Answer 26

Viruses can secrete analogs of immune regulators such as cytokines.

Question 27

Immune-escape Mutants

Answer 27

Genetic variation leading to antigenic variation, common in RNA viruses which have higher mutation rates (ex: HIV or Rhinoviruses)

Question 28

Glycosylation

Answer 28

Coating the surface antigens with sugars to render them as poor immunogens. (ex: HIV GP120)

Question 29

Hide Receptor Binding Sites

Answer 29

Rhinoviruses- the receptor binding site is in a canyon that cannot be accessed by antibodies, has over 100 different serotypes.

Question 30

Hide in Immune Privileged Sites

Answer 30

Polyoma viruses like Jc simian virus 40 hide in the kidney tubules, HSV - hides in neurons

Question 31

Immune Privileged Sites

Answer 31

Nervous system, brain, and Fetus

Question 32

Influenza

Answer 32

Leads to release of pro-inflammatory cytokines by the innate immune system that result in fever, body-aches etc.

Question 33

HBV

Answer 33

Tissue damage is due to the CD8 + T cells and pro-inflammatory cytokines that attack virus infected tissues.

Question 34

Coxsackievirus B3

Answer 34

Myocarditis due to the CD8 + T cell immune response and TNF-alpha and IL-1beta. Coxsackie B4 attacks the pancreas and is believed to trigger diabetes but is not proven.

Question 35

Herpes Stromal Keratitis

Answer 35

HSV-1 coat proteins cross-react with corneal antigens, leading to destruction

Question 36

Multiple Sclerosis

Answer 36

Been associated with several viruses but viral etiology is not proven.

Question 37

Guillain-Barre Syndrome

Answer 37

HCMV and Clostridium jejuni produce antibodies that are cross reactive to GM2 a ganglioside present on motor neurons. Results in limb weakness and paralysis.