Immune Responses to Viruses

Question 1

• all viruses are ________ pathogens
• when extracellular, viruses are susceptible to ___________
• when intracellular, _________ is required to eliminate viruses, especially persistent/latent

Answer 1

• obligate intracellular
• neuatralizing antibody and complement
• cell mediated immunity

Question 2

• present in newborns
• important early in infections
• involves recognition of patterns, not epitopes
• unaffected by vaccines
• does not result in memory for the pathogen

Answer 2

innate immunity

Question 3

in innate immunity, NK cells recognize virus encoded _____ on infected host cells

Answer 3

virus encoded

Question 4

• induced by TLR and NLR signaling
• act through cell surface receptors
• inhibit viral translation and cause degradation of viral RNA
• increase MHC-1 path of antigen presentation

Answer 4

interferons

Question 5

C3b and C3d are normally found attached to antigens and help co-activate the B cell through ______

Answer 5

co-receptor CR2

Question 6

_______ viruses are generally susceptible to lysis by complement, lytic viruses are generally resistant

Answer 6

enveloped (budding)

Question 7

C3b and iC3b serve as _______, C3b can block viral _______ to host cell surface receptors

Answer 7

opsonins, attachment

Question 8

• bear inhibitory receptors that recognize MHCI, apoptosis of virus infected cells induced by perforin/granzyme system and Fas/Fas ligand signaling
• produce interferons, which inhibit viral replication

Answer 8

NK cells

Question 9

• specific for antigenic epitopes
• neutralize and eliminate extracellular viral pathogens
• CD8 kill virus infected cells
• CD4 promote antibody production and CTL activation

Answer 9

adaptive immunity

Question 10

antibodies against virus encoded cell surface antigens ca eliminate virus infected cells through?

Answer 10

opsonophagocytosis (Fc receptors)
complement attack (IgM, IgG, classical)
antibody dependent cell toxicity

Question 11

• promote antibody formation by B cell proliferation and Ig class switching
• promote CTL growth and differentiation (IL-2)
• NK cell activation and lysis of virus infected cells
• promote macrophage activation –> oxidative damage to viruses (IFN-gamma)

Answer 11

T helper cells

Question 12

• important for resolving infection
• primarily CD8 T cells (perforin/granzyme, Fas/FasL)
• function impaired in T cell deficient patients, lead to opportunistic infections

Answer 12

cytotoxic T cells

Question 13

vaccines induce?

Answer 13

immunologic memory (T and B cell)

Question 14

• level of immunity in a population, which effectively prevents the spread of disease
• provides indirect protection to unimmunized individuals by decreased pathogen load
• accounts for disappearance of disease when immunization rates approach 100%

Answer 14

herd immunity