Host Response Flashcards Preview

RUSVM Virology > Host Response > Flashcards

Flashcards in Host Response Deck (50)
1

Recepter on the NK cell that binds to the MHC molecule on normal cell

Inhibitory receptor

2

Leukocyte interferon, produced in large quantities by plasmacytoid dendritic cells and is not host specific

INF-Alpha

3

When is gene silencing used?

Cells can utilize this mechanism to disrupt virus replication through production of RNAi that are complementary to specific viral genes

4

Antigenic Plasticity

Rapid changes in the structure of the viral antigen, may be the result of mutation, reassortment or recombination

5

(RNA/DNA) viruses are stronger inducers of Interferons

RNA

6

Possess potent antiviral, immunomodulating and anti-cancer properties

Interferons

7

NK cells recognize what molecules on healthy cells that keeps them from becoming activated

MHC Class I Molecules

8

Innate immune system responds in what ways when their PPRs are bound by a PAMP

Expression of interferons and inflammatory cytokines

Activation of phagocytic cells, increased production of inflammatory cells

Macrophages begin chemotaxis bringing neutrophils to site of inflammation

9

Interferon

Group of cytokines that are secreted by somatic cells in response to viral infections and to other stimuli

10

Ways in which Host responds to viral infection

Innate immune response

Adaptive immune response

Passive immune response

11

Natural Killer Cells

Large lymphocytes that are defined by their cytoplasmic granules, provide early and non specific resistance against viral infections

12

Virokines

Proteins synthesized by viruses which are homologs of cytokines/interferons

13

Ways that viruses evade host immune system

Antigen plasticity

Antigenic Multiplicity

Negative Cytokine Regulation 

Down Regulation of MHC I Pathway

Inhibition of complement activation

Evasion of neutralizing antibodies

Latency

Cell to Cell spread

Inhibition of apoptosis

14

Humoral Immunity

Antibodies may be directed against viral proteins on free virions or against viral proteins expressed on surface of infected cells

15

CD4+ Th Cell mechanism of action

  • Th interacts with microbial antigen in phagocyte
  • Stimulates the release of cytokines
  • Results in activation of macrophages, inflammation and Stimulation of B lymphocytes

16

Cellular immunity is mediated by

T Lymphocytes

17

Immunoregulatory interferon produced by antigen stimulated by T cells and NK cells.  Labile at pH of 2 and demonstrates host specificity

Type II Interferon - Interferon Gamma

18

Defense exhibits neither antigen specificity nor memory

 Innate Immunity

19

Components of adaptive immunity

Humoral Immune Response

Cellular Immune Response

20

Paracrine

Infected cell secretes IFN which acts on adjacent cells

21

Temperature of the nasal passages

33C

22

Gene Silencing 

Cells utilize small, interfering RNA molecules (iRNA) to silence genes as a means of regulating normal developmental and physiological processes and potentially to interfere with virus replication

23

Interferons are inactivated by what route of administration

Oral

24

Innate immunity provides critical line of defense against viral infections because:

Constantly present

Operational immediately

Available for the first few days after viral infection

25

Temperature of the alveoli

37C

26

Fibroblast interferon secreted by virus-infected fibroblast, generally host species specific

INF - Beta

27

Granulocytosis

Presence in peripheral blood of increased number of granulocytes

28

Pathogen Associated Molecular Patterns

Macromolecues present in viruses and other microbes, but not on host cells

29

Antiviral effects of antibodies

Reduced damage to host from inflammatory response

Generation of oxidants

Immunomodulation

Opsonization

Activation of complement

Virus and toxin neutralization

Antibody dependent cell cytoxicity

Direct antimicrobial activity

30

Perforin

Produce pore in plasma membrane

31

Activation of the complement system causes

Opsonization

Chemotaxis

Lysis

Agglutination

32

How do viruses evade neutralizing antibodies

Produce large amounts of soluble protein to soak up antibody

Variation in viral antigens

Production of antibodies capable of neutralization

Slow production of antibodies

33

Antibody dependent cell mediated cytotoxicity

Antibodies bind to viral antigens expressed on surface of host cells, host cells are destroyed by phagocytosis or by complement mediated cytolysis

34

Virus Neutralization

Neutralizing antibodies prevent virus attachement and entry into host cells, bind viral capsid or host envelope

35

Viroceptors

Virus encoded proteins that are homologous to the receptor for cytokines, secreted cytokine receptor homolog bind to cytokines and serve as competitive antagonists

36

Autocrine

infected cell secretes the INF that acts on same cell triggering apoptosis

37

Opsonization

Coating of virions with antibodies, antibody coated virion is recognized and phagocytosed by macrophages and sometimes by neutrophils

38

How do type I interferons inhibit virus replication

  • Activate latent ribonuclease - RNAase L
  • RNAase L degrades viral RNA
  • Synthesis of Mx proteins that bind and trap nucleocapsid and inhibit virus assembly

39

Adaptive Immunity

Antigen specific, responses take time to develop and is mediated by lymphocytes that possess surface receptors that are specific to each pathogen

40

Pattern Recognition Receptors

Surface receptors that recognize specific pathogen associated molecular patterns.

41

Mucocilliary Blanket

Layer of mucous produced by goblet cells that is kept in continuous flow by the coordinated beating of cilia on the luminal surface of the epithelial cells that line the nasal mucosa and airways

42

Antigen Multiplicity

Antigenic varients with little or no cross reactivity

43

Granzyme

Proteins that initiate apoptosis

44

At least three interferons have been identified, recently discovered.  Expressed in response to viral infections and activation of toll-like receptors.  Primary function as immuno regulator

Type III Interferon

45

Major classes of interferons based on antigenic and chemical differences

Type I

Type II

Type III

46

Roles of type I interferons

Inhibit virus replication

Activate NK cells

Increase expression of MHC-1

Stimulate differentiation of monocytes into dendritic cells

Maturation of dendritic cells

Memorty T cell proliferation

47

CD8+ Tc Cell mechanism of action

  • Tc cell interaction with infected cell containing microbial antigen
  • Killing of infected cell

48

Humoral immunity is mediated by

Antibodies released from B lymphocytes

49

Immunocomplex formation

Clumping of viruses, reduces the number of viral particles avilable for cell invasion

50

Cytoplasmic granules of NK cells contain

Perforin

Granzyme