Immunity to viruses

Question 1

What is the role of the immune system in viral infections?

Answer 1

To detect the virus as non-self remove it prevent disease and stop viral spread

Question 2

What are the four levels of host defense against viruses?

Answer 2

Anatomical and chemical barriers intrinsic defenses innate immunity and acquired immunity

Question 3

What intrinsic defenses exist in uninfected cells?

Answer 3

Autophagy apoptosis anti-viral proteins and pathogen recognition receptors PRRs

Question 4

What innate immune responses are induced by viral infections?

Answer 4

Natural killer NK cells interferons IFN cytokines and the complement system

Question 5

What components of acquired immunity target viruses?

Answer 5

CD8+ cytotoxic T lymphocytes CD4+ helper T cells antibodies and immunological memory

Question 6

What are PAMPs and PRRs in viral sensing?

Answer 6

Pathogen-associated molecular patterns PAMPs are detected by pattern recognition receptors PRRs like Toll-like receptors and RIG-1

Question 7

What is the role of interferons in antiviral immunity?

Answer 7

Interferons IFN-alpha and IFN-beta induce an antiviral state in uninfected cells and enhance immune responses

Question 8

What are interferon-stimulated genes ISGs?

Answer 8

Genes activated by interferons that inhibit viral replication by degrading viral RNA and inhibiting protein synthesis

Question 9

How do NK cells recognize and kill infected cells?

Answer 9

NK cells detect the absence of MHC Class I molecules on infected cells and induce lysis

Question 10

What are the main antiviral effects of the immune system?

Answer 10

Neutralization of free virus, lysis of infected cells via complement and enhancing NK cell cytotoxicity

Question 11

What are the roles of CD8+ and CD4+ T cells in viral immunity?

Answer 11

CD8+ T cells kill infected cells while CD4+ T cells provide help by producing cytokines and enhancing immune responses

Question 12

What are viral evasion strategies?

Answer 12

Antigenic variation interference with antigen processing limiting gene expression and inhibiting PRR or interferon signaling

Question 13

What is antigenic drift and shift in viral evasion?

Answer 13

Antigenic drift involves mutations in viral RNA while antigenic shift occurs when segmented genomes exchange segments creating new virus strains

Question 14

How does HIV evade immune responses?

Answer 14

HIV undergoes mutations that change antigenic epitopes avoiding recognition by CD8+ T cells

Question 15

What is latency and how do viruses use it?

Answer 15

Latency is a strategy where viruses like herpesvirus express minimal or no proteins to evade detection

Question 16

How do herpesviruses block antigen presentation?

Answer 16

By inhibiting TAP transporters preventing peptide loading onto MHC Class I molecules

Question 17

What is the role of cytokine and chemokine homologues in viral evasion?

Answer 17

Viruses produce homologues to interfere with host immune signaling pathways

Question 18

What are examples of immune evasion in herpesviruses?

Answer 18

Herpes simplex virus establishes latency and cytomegalovirus downregulates MHC Class I to escape CD8+ T cells

Question 19

How does interferon resistance aid viral survival?

Answer 19

Viruses like vaccinia produce proteins that block interferon signaling reducing the antiviral state

Question 20

How does immunological memory improve responses to reinfection?

Answer 20

Memory T and B cells allow for faster and more effective responses to previously encountered viruses

Question 21

What is the role of PRRs like RIG-1 in antiviral immunity?

Answer 21

PRRs recognize viral RNA and activate signaling pathways leading to interferon production

Question 22

What is the importance of the complement system in viral immunity?

Answer 22

The complement system lyses virus-infected cells and enhances antibody responses

Question 23

How do viruses inhibit PRR signaling pathways?

Answer 23

Viruses like Ebola and HCV produce proteins that block RIG-1 or Toll-like receptor signaling to evade detection

Question 24

What are some therapeutic targets for managing viral infections?

Answer 24

Blocking viral replication enhancing interferon responses and boosting adaptive immunity through vaccines