Host Response to Viral Infection Flashcards
What are 3 types of host immune response?
- Innate immunity
- Adaptive immunity
- Passive immunity
T/F: Innate immunity defenses exhibit antigen specificity and memory
False; do not exhibit antigen specificity or memory
Innate immunity is the ________ line of defense against viral infection
First
T/F: Innate immunity has primary physical and chemical defenses
True
What are the 2 primary physical and chemical defenses of respiratory tract?
- Mucociliary blanket
2. Temp. Gradient
NK cells mediate cell death via ___________
Apoptosis
One class of PRRs are ___________
TLRs (toll-like receptors)
PRRs recognize ___________
PAMPs (pathogen specific associated molecular patterns)
Interferons are secreted by _________ cells in response to viral infections an other stimuli
Somatic
Interferons possess what 3 properties?
Potent antiviral, immunomodulating, and anti-cancer properties
T/F: Interferons have virus specificity
False; have no virus specificity
Who is stronger inducer of interferons? DNA or RNA viruses?
RNA viruses
Why should interferons be administered by injection?
Because they are orally inactive
What is IFN-α?
Leukocyte interferon produced in large quantities by dendritic cells
What is IFN-β?
Fibroblast interferon secreted by virus infected fibroblast
IFN-α & IFN-β are what type of interferons?
Type 1
What are some roles of type-1 IFNs?
- Inhibit virus replication
- Activate NK cells
- Increase MHC-1 expression
- Maturation of dendritic cells
- Stimulate memory T-cell proliferation
Type-II interferon has INF-_____
IFN-γ
What is the main function of IFN-γ?
Mostly immunoregulatory
What 3 types of IFN are in type-III interferons?
IFN-λ1
IFN-λ2
IFN-λ3
What is the primary function of type-III IFNs?
Immunoregulator
Type-III IFNs are expressed in response to what two things?
- Viral infections
2. TLRs
Adaptive immunity includes ___________ and ____________ components
Humoral and cellular
Adaptive immunity is __________ specific
Antigen
Humoral immunity is mediated by Ab released from ___ lymphocytes and cellular immunity is mediated by ___ lymphocytes
- B
2. T
Adaptive immunity stimulates _____-term memory after infection
Long
Antibodies may be expressed by what two types of viral proteins?
- Viral proteins on free virions
2. Viral proteins expressed on surface of infected cells
What does virus neutralization do?
Prevents virus attachment and entry into host cells; they bind to viral capsid or host envelope
What is opsonization?
Coating of virions with antibodies so it is recognized and phagocytosed by macrophages and sometimes neutrophils
What are 5 antiviral effects on antibodies?
- Virus neutralization
- Opsonization
- Clumping of viruses
- Activation of compliment system
- Antibody-dependent cell-mediated cytotoxicity
What are 4 components of cell mediated immunity?
- Activation of macrophages
- Inflammation
- Stimulation of B lymphocytes
- Killing of infected cells
T/F: adaptive immunity is virus specific
True
What are 9 ways viruses evade the immune system?
- Antigen plasticity
- Antigen multiplicity
- Negative cytokine regulation
- Down-regulation of MHC class 1 pathway
- Inhibition of compliment activation
- Evasion of neutralizing antibodies
- Latency
- Cell-to-cell spread of viruses
- Inhibition of apoptosis
What is antigenic plasticity?
Rapid changes in structure of viral antigen
What is antigenic multiplicity?
Antigenic variants with little or no cross-reactivity
What are virokines?
Viruses that synthesize proteins that are homologs of cytokines/IFNs
What are viroceptors?
Viruses that encode proteins that are homologous to receptors for cytokines
