Host Response to Viral Infection Flashcards
What are the host immune responses to viral infections?
Innate Immunity, Adaptive Immunity, Passive Immunity
T/F: Innate immune defenses exhibit antigen specificity but no memory.
FALSE!!
Innate immune defenses exhibit NEITHER antigen specificity nor memory.
Which immune response is the first line of defense against viral infections?
Innate Immunity
The following are reasons why the innate immunity is a critical first line of defense against viral infections EXCEPT:
A. They are operational immediately after viral infection
B. They are constantly present
C. Are the only immune defense available for the first few days after viral infection
D. They are antigen specific
D. They are antigen specific
– Innate Immunity is not antigen specific ; the adaptive immunity is!
What are the Primary physical and chemical defenses of the innate immunity?
- Skin
- Mucous membrane
- G.I tract
- Respiratory tract
All of the following are defenses of the G.I tract for innate immunity EXCEPT:
A. Mucous membrane of oral cavity and esophagus that is refractory to viruses
B. Basicity of the stomach
C. Alkalinity of Intestine
D. Layer of mucus covering the gut
E. Lipolytic activity of bile
F. Proteolytic activity of Pancreatic enzymes
G. Defensins (host defense peptides) with antiviral activity. (which modulate the host immune response)
B. basicity of the stomach
–should say “Acidity of the stomach” to make it true.
What two defenses does the respiratory tract of the innate immunity have?
- Mucociliary Blanket
2. Temperature gradient
T/F: There is a temperature gradient between the nasal passage (33 degrees Celsius) and the alveoli (37 degrees Celsius) that plays an important role in the localization of infection.
True
T/F: Rhinoviruses, which infect the nasopharynx and cause the common cold, replicate well at 37 degrees Celsius but grow poorly at 33 degrees Celsius. Influenza Virus which infect the lower respiratory tracts, shows the inverse temperature preference.
FALSE!!
Rhinoviruses, which infect the nasopharynx and cause the common cold, replicate well at 33 degrees Celsius but grow poorly at 37 degrees Celsius. Influenza Virus which infect the lower respiratory tracts, shows the inverse temperature preference.—> this is TRUE
–the nasopharynx has a temperature of 33 degrees , the respiratory tracts have a temperature of 37 degrees!
How do NK cells mediate death of virus infected cells?
via apoptosis
Cells at portals of virus entry possess surface receptors called __________ and is apart of the innate immunity.
Pattern recognition receptors (PRR)
T/F: Pattern recognition receptors (PRR) recognize Pathogen- associated molecular patterns (PAMPs).
True
T/F: One class of PRRs are the TLRs
True
Toll like receptors can simulate the macrophage to cause all of the following EXCEPT: A. Phagocytosis B. Chemotaxis C. Inflammatory Mediators D. Interferons E. Antibodies
E. Antibodies
-Antibodies are a part of the adaptive immunity not the innate immunity; and TLRs are apart of the Innate immunity.
______ are a group of cytokines (complex glycoproteins) that are secreted by somatic cells in response to viral infections and to other stimuli.
Interferons (IFN)
What 3 properties does Interferons possess?
- Potent antiviral
- Immunomodulating
- anti- cancer properties
T/F: Interferons show virus specificity.
FASLE!!!
Interferons show NO virus specificity.
T/F: RNA viruses are stronger inducers of interferon than DNA viruses.
True
T/F: Being glycoproteins, interferons are orally inactive, and should be administered to the patient by parenteral route (injection).
True
What are the 3 major classes of interferons based on antigenic and chemical differences?
1) Type- I
2) Type- II
3) Type- III
What are the type I interferons?
1) IFN- alpha
2) IFN- beta
Which interferon is produced in large quantities by plasmacytoid dendritic cells, and is a leukocyte interferon?
IFN- alpha
Which interferon is secreted by virus- infected fibroblast and is a fibroblast interferon?
IFN- beta
All of the following are roles of type- I interferons EXCEPT:
A. Inhibit virus replication in host cells
B. Activate NK cells to kill infected cells
C. Increase expression of MHC-II molecules and antigen presentation
D. Stimulate differentiation of monocytes into dendritic cells
E. Maturation of dendritic cells
F. Stimulates memory T cell proliferation
G. All of the above are true
C. Increase expression of MHC-II molecules and antigen presentation
- should say “Increase expression of MHC-I molecules and antigen presentation”
- -MHC- I not MHC-II
Which interferon is in the Type- II class of interferons?
INF- gamma
Which interferon is mostly immunoregulatory and is produced by antigen- stimulated T cells and NK cells?
INF- gamma
Which class of interferons have been the most recently discovered?
Type- III
3 interferons have been identified in this class: IFN- gamma1, IFN- gamma2, and IFN- gamma3
Which class of interferons is expressed in response to viral infections and activation of TLRs?
Type- III
What is the primary function of Type- III interferons?
Immunoregulators
___________ immunity includes humoral and cellular components.
Adaptive
T/F: Adaptive immunity is mediated principally by antibodies released from B lymphocytes.
True
T/F: Cellular immunity is mediated by B lymphocytes.
FALSE!!
-Cellular immunity is mediated by T lymphocytes.
Is adaptive immunity antigen specific?
Yes, it is antigen specific
T/F: Adaptive immunity is antigen specific, so these responses take time (several days at least) to develop, and this type of immunity is mediated by lymphocytes that possess surface receptors that are SPECIFIC to each pathogen.
True
T/F: Adaptive immunity does not stimulate long term memory after infection.
FALSE!
– Adaptive immunity stimulates long term memory after infection
Internal viral antigens usually elicit what type of protective response?
Cell Mediated Immune response
Surface antigens elicit which type(s) of protective immune response(s)?
Humoral and Cell Mediated Immune responses!
T/F: Internal antigens elicit protective cell mediate Immune response while surface antigens elicit protective humoral response only!
FALSE!
–Internal antigens elicit protective cell mediate Immune response while surface antigens elicit BOTH protective humoral AND Cell mediated immune responses!!
What are the two types of Adaptive Immunity?
1) Humoral Immunity (antibody- mediated Immunity)
2) Cell Mediated Immunity
Antibodies may be directed against viral proteins on free virions (capsid or envelop), or against viral proteins expressed on the surface of infected cells in _____________ immunity.
Humoral (Antibody- mediated)
What are the 5 antiviral effects of antibodies?
1) Virus Neutralization
2) Opsonization
3) Clumping of Viruses (Immunocomplex Formation)
4) Activation of complement system
5) Antibody- dependent Cell- Mediated Cytotoxicity
During Virus neutralization where do antibodies binds to?
Viral capsid or Host envelope
During virus neutralization neutralizing antibodies prevents what?
Prevents virus attachment and entry into the host cell
Coating of virions with antibodies is the definition of _________.
Opsonization
During opsonization, antibody coated virion is recognized and phagocytosed by ______A______, and sometimes by _____B_______.
A. Macrophages
B. Neutrophils
What is the antiviral effect of clumping of viruses (Immunocomplex formation)?
It reduces the number of viral particles available for cell invasion
CD4+ helper T lymphocyte, after binding with an APC, stimulates the release of cytokines resulting in which of the following? A. Activation of Macrophages B. Inflammation C. Stimulation of B Lymphocytes D. Kills the infected cell E. A., B., and C. F. All of the above
E.
CD8+ Cytotoxic T lymphocyte, after binding with an APC, results in which of the following? A. Activation of Macrophages B. Inflammation C. Stimulation of B Lymphocytes D. Kills the infected cell E. A., B., and C. F. All of the above
D.
All of the following are ways viruses evade the immune system EXCEPT: A. Antigenic Plasticity B. Antigenic Multiplicity C. Negative Cytokine Regulation D. Down- regulation of MHC class II pathway E. Inhibition of complement activation F. Evasion of Neutralizing Antibodies G. Latency H. Cell-to-Cell Spread of Viruses I. Inhibition of Apoptosis
D. Down- regulation of MHC class II pathway
– Should say “Down- regulation of MHC class I pathway”
Rapid changes in the structure of the viral antigen is known as ?
Antigenic plasticity
Antigenic plasticity may be the result of ___A____, ____B_____, or ______C______.
A. mutation
B. reassortment
C. recombination
T/F: During Antigenic Plasticity, due to change in antigen structure, the virus may become resistant to immunity generated by previous infection.
True
Antigenic variants with little or no cross- reactivity= Antigenic _________.
Multiplicity
Viruses evade the immune system via Negative Cytokine Regulation which is made up by ____A_____ and ____B_____.
A. Virokines
B. Viroceptors
Some viruses SYNTHESIZE proteins which are homologs of cytokines/ interferons. This is knows as ___________, a negative cytokine regulation.
Virokines
Some viruses ENCODE proteins that are homologs to the receptors for cytokines. This is knows as ___________, a negative cytokine regulation.
Viroceptors
Which one serves as a competitive antagonist, Virokines or Viroceptors?
Viroceptors
