(Final) Host response to Viral Infection Flashcards
What 3 host immune responses can your body have to a viral infection?
Innate immunity
adaptive immunity
passive immunity
What is the first line of defense against infections?
Innate immunity
Does the innate immunity exhibit memory or specificity?
NO
What are the only immune defense available after the first few days after viral infection?
Innate immunity
Provides primary physical and chemical defenses
Where are defensins located in the body and what is their function?
Defensins = host defense peptides with antiviral activity. They are located in the GI tract and modulate the host immune response
What are the primary defense mechanisms of the respiratory tract?
Mucociliary blanket and temperature gradient (nasal passages = 33C - alveoli = 37C)
By which mechanism do natural killer cells mediate cell death?
Inducing apoptosis via perforin and granzymes
What receptors recognize pathogen associated molecular patterns (PAMPs)?
PRR - pattern recognition receptors
One class of PRRs are the Toll Like Receptors (TLRs)
Where are TLRs present? (on what cells)
Macrophages, neutrophils, endothelial cells etc
What are the results of TLR stimulation?
Phagocytosis
Chemotaxis
Inflammatory mediators
Inferferons
T/F: If TLRs are being chronically/constantly stimulated, there may be an auto immune response
TRUE
What are interferons?
IFN = a group of cyotokines that are secreted by somatic cells in response to viral infections and other stimuli
T/F: IFN posses potent antiviral, immunomodulating, and anti cancer properties
TRUE
T/F: DNA viruses are stronger inducers of interferon that RNA viruses
FALSE
RNA viruses are stronger inducers of IFN than DNA viruses
What are the 3 major classes of interferon based on antigenic and chemical difference?
Type I = IFN alpha and IFN beta
Type II = IFN gamma
Type III = IFN lambda1, IFN lambda2, IFN lambda 3
What kind of interferons are IFN alph and IFN beta?
IFN alpha = leukocyte interferon. Produces large quanities of plasmacytoid dendritic cells
IFN beta: fibroblast interferon. Secreted by virus infected fibroblasts
What is the function of Type 1 interferons?
Inhibit virus replication in host cells
Activate NK cells to kill infected cells
Increase the expression of MHC-1 molecules and antigen presentation
Stimulate differentiation of monocytes into dendritic cells
Maturation of dendritic cells
Stimulates memory T cell proliferation
What are the 2 primary functions of Interferon alpha and beta?
Apoptosis via autocrine signaling
Inhibition of virus replication via paracrine signaling
What is the function of type II interferons?
Type II = Infereron gamma
Mostly immunoregulatory - produced by antigen stimulated T cells and NK cells
What is the primary function of Type III interferons? (Lambda)
Immunoregulation
These are expressed in response to viral infections and activation of TLRs
T/F: Interferons aare virus specific (for each virus there will be a specific interferon)
FALSE
THEY ARE NON SPECIFIC
What gene is responsible for gene silencing?
SIRNA = Short interfering RNA
What are the components of adaptive immune system?
Humoral and cellular
Humoral immunity is mediated by _________ that are released from B lymphocytes
Antibodies
Cellular immunity is mediated by what cells?
T lymphocytes
What immune response will stimulate long term memory after an infection?
Adaptive immunity
What does the adaptive immunity produce antibodies against during a viral infection?
Against viral proteins on free virions (capsid or envelope)
OR
Against viral proteins expressed on surface of infected cells
What can antibodies do to defend against a viral infection?
Virus neutralization
Opsonization
Immunocomplex formation (clumping of viruses)
Complement system activation
Stimulate antibody dependent cell mediated cytotoxicty
What cells partake in the cell mediated immunity?
CD4 helper T cells and CD8 cytotoxic T cells
What is antigenic plasticity?
Rapid changes in the structure of the viral antigen
Can be due to a mutation, reassortment, or recombination
What is antigenic multiplicity?
Antigenic variants with little or no cross-reactivity
can have many viral serotypes
What is the process of negative cytokine regulation?
Blocking of the interferon receptor signal.
Virokines: some viruses synthesize proteins which are homologs of cytokines/interferons
Viroreceptors: Some viruses encode proteins that are homologous to the receptors of cytokines. (serve as a competitive antagonist)
T/F: Down regulation of MHC class I pathways and Inhibition of complement activation are examples of viral evasion of the immune system
TRUE
What are some ways viruses can evade the immune system?
Evasion of neutralizing ABs, Latency, Cell to cell spread, inhibition of apoptosis, inhibition of complement, down regulation of MHC-I, negative cytokine regulation
T/F: Rapid changes in the structure of viral antigen of a virus over time due to mutations is also known as Antigenic Multiplicity
FALSE
this is describing antigenic plasticity
