Immunity to Viruses

Question 1

Immunity to Viruses
Mechanisms:
Soluble extracellular factors

Answer 1

– neutralizing antibody and complement (opsonin)

Question 2

Immunity to Viruses
Mechanisms:
Inhibition of intracellular replication

Answer 2

– interferons, host cell

Question 3

Immunity to Viruses
Mechanisms:
Immune-mediated lysis of infected cells

Answer 3

– CTL (CD8) and NK cells

Question 4

Innate immune system:

Pattern recognition

Answer 4

– C-type lectins, membrane TLRs, cytosol sensors (Nod-like receptor), NK cells (viral surface products)

Question 5

Innate immune system:

Soluble

Answer 5

– complement, interferons, cytokines recognize and neutralize free virons

Question 6

Innate immune system:
Soluble
Interferons

Answer 6

– induced by TLRs → act via Jak/Stat → ↑transcription of MHC-1 for better viral antigen presentation

Question 7

Innate immune system:
Soluble
Complement

Answer 7

– C3b opsonin → phagocytes, blocks viral attachment, enveloped viruses, EBV uses C3b to facilitate binding

Question 8

Innate immune system:
Soluble
NK cells

Answer 8

– activated by ↓ MHC-1 → granzymes, perforin → apoptosis of infected cells, produce IFN, recognize Ab coated cells

Question 9

Innate immune system: Importance

Answer 9

– newborns, early infection, pattern recognition, no memory, unaffected by vaccine

Question 10

Adaptive immune system:

Antibody

Answer 10

– mucosal secretory IgA, protective Ab to epitopes, IgG/M clearance, block attachment/uncoating, target infected cells

Question 11

Adaptive immune system:

Seroconversion

Answer 11

Seroconversion – rise in serum antibody titer, 4-fold increase indicates acute/chronic infection

Question 12

Adaptive immune system:

CTLs

Answer 12

CTLs – resolving infection, latent and persistent infection, facilitate apoptosis, impaired with T cells deficiency

Question 13

Adaptive Immune System:

T helper

Answer 13

T helper – regulate Ab production (class switching), CTL differentiation, NK activation, IFN-γ production

Question 14

Adaptive immune system:

Importance

Answer 14

Importance – extracellular and intracellular elimination, induced by vaccines, low function in infants/immunocompromised

Question 15

Microbial immune evasion:

Answer 15

co-evolves with immune mechanisms

Question 16

Microbial immune evasion:

Cell-to-cell spread

Answer 16

Cell-to-cell spread – avoids extracellular environment, latency and avoidance of detection

Question 17

Microbial immune evasion:

Antigenic variation

Answer 17

Antigenic variation – Abs can recognize, shift and drift allows for reinfection of a new strain, seasonal vaccines

Question 18

Microbial immune evasion:

MHC

Answer 18

MHC – downregulation of MCH inhibits antigen presentation and recognition of infected cells, HSV, CMV, EBV

Question 19

Microbial immune evasion:

Cytokines

Answer 19

Cytokines - production of mimic cytokines, soluble receptors

Question 20

Microbial immune evasion:

Apoptosis

Answer 20

Apoptosis – blocked by viruses, promotes immortalization and chances for mutation

Question 21

Types of vaccines:

Subunit

Answer 21

• recombinant antigen protein → Ab production – Hep B

Question 22

Types of vaccines:

Inactivated

Answer 22

Inactivated – dead whole virus → no mucosal immunity – Polio, HAV, rabies

Question 23

Types of vaccines:

Attenuated live

Answer 23

Attenuated live – whole weakened virus → mucosal immunity, CD8 cells

Question 24

Vaccine Schedule

Answer 24

Schedule – certain vaccines interfere with maternal IgG, blood products, other vaccines, etc.

Question 25

Immune globulin:

Uses

Answer 25

vaccine does not exist, progression is rapid, viral load reduction is critical, or viremia is common

Question 26

Immune globulin:

IVIG

Answer 26

IVIG - some neutralizing antibodies, pathogen-specific IG, post-exposure, ex: rabies, HBV

Question 27

Risks for viral infections:

Marrow transplant

Answer 27

– cyclosporine, GVH → herpes infections are common, CMV

Question 28

Risks for viral infections:

Antibody deficiency

Answer 28

Antibody deficiency – enteroviruses, respiratory viruses

Question 29

Risks for viral infections:

T cell deficiency

Answer 29

T cell deficiency – herpes viruses