Podcast
Questions and Answers
What is activated in the innate immune response to viruses?
What is activated in the innate immune response to viruses?
- Viral PRRs (correct)
- Mitochondrial DNA
- B cell receptors
- T cell receptors
Which type of cytokines are synthesized during the innate immune response to viruses?
Which type of cytokines are synthesized during the innate immune response to viruses?
- Neurotransmitters
- Secondary messengers
- Type I interferons (correct)
- Anti-inflammatory cytokines
What is the primary goal of viruses in relation to the immune system?
What is the primary goal of viruses in relation to the immune system?
- Survive and evade immune responses (correct)
- Infect host cells
- Maximize replication rate
- Enhance cytokine production
What characterizes the innate immune response to viruses?
What characterizes the innate immune response to viruses?
How have viruses adapted to face the immune system?
How have viruses adapted to face the immune system?
Which type of receptors recognize viral capsid proteins?
Which type of receptors recognize viral capsid proteins?
What is the primary function of type I interferons (IFNs) after viral recognition?
What is the primary function of type I interferons (IFNs) after viral recognition?
Which cells are activated by type I interferons to enhance immune response?
Which cells are activated by type I interferons to enhance immune response?
Which receptor is primarily responsible for recognizing viral RNA?
Which receptor is primarily responsible for recognizing viral RNA?
What immune response do NK cells have against infected cells?
What immune response do NK cells have against infected cells?
What occurs to MHC class I molecules in response to type I interferons?
What occurs to MHC class I molecules in response to type I interferons?
Which of the following is NOT a result of type I interferon action?
Which of the following is NOT a result of type I interferon action?
What is one of the key roles of dendritic cells (DC) upon activation by type I interferons?
What is one of the key roles of dendritic cells (DC) upon activation by type I interferons?
What is the main cytokine produced by virally-infected cells?
What is the main cytokine produced by virally-infected cells?
Which immune cells are primarily responsible for killing virally-infected cells?
Which immune cells are primarily responsible for killing virally-infected cells?
What type of receptors do NK cells possess to identify infected cells?
What type of receptors do NK cells possess to identify infected cells?
What is the role of antibodies against viruses?
What is the role of antibodies against viruses?
How do NK cells differentiate between infected and uninfected cells?
How do NK cells differentiate between infected and uninfected cells?
What happens to NK cells when they encounter uninfected cells?
What happens to NK cells when they encounter uninfected cells?
Which of the following cytokines is least likely to be produced by virally-infected cells?
Which of the following cytokines is least likely to be produced by virally-infected cells?
What type of immune response do CTLs primarily contribute to?
What type of immune response do CTLs primarily contribute to?
What strategy do viruses use to avoid being attacked by NK cells?
What strategy do viruses use to avoid being attacked by NK cells?
What is a key function of NK cells in the immune response?
What is a key function of NK cells in the immune response?
Which immune cells also have a role in killing virally-infected cells alongside CTLs?
Which immune cells also have a role in killing virally-infected cells alongside CTLs?
In what way do NK cells kill infected cells?
In what way do NK cells kill infected cells?
What mechanism do antibodies use to neutralize viruses?
What mechanism do antibodies use to neutralize viruses?
Which is NOT a characteristic of uninfected cells regarding NK cell activity?
Which is NOT a characteristic of uninfected cells regarding NK cell activity?
In which scenario would IL-10 be most relevant?
In which scenario would IL-10 be most relevant?
What role does the activatory receptor play for NK cells?
What role does the activatory receptor play for NK cells?
What mechanism allows viruses to evade detection by the immune system?
What mechanism allows viruses to evade detection by the immune system?
What is a consequence of down-regulating MHC class I on infected cells?
What is a consequence of down-regulating MHC class I on infected cells?
What does antigenic drift in influenza refer to?
What does antigenic drift in influenza refer to?
Which virus is specifically mentioned as having a protein that inhibits antigen processing?
Which virus is specifically mentioned as having a protein that inhibits antigen processing?
What event leads to anti-viral antibodies becoming ineffective against the influenza virus?
What event leads to anti-viral antibodies becoming ineffective against the influenza virus?
What kind of changes does antigenic shift refer to in viral antigens?
What kind of changes does antigenic shift refer to in viral antigens?
How does the herpes simplex virus (HSV) evade the immune response?
How does the herpes simplex virus (HSV) evade the immune response?
What is the effect of viruses that down-regulate MHC class I?
What is the effect of viruses that down-regulate MHC class I?
What is a major factor that allows influenza to frequently evade the immune response?
What is a major factor that allows influenza to frequently evade the immune response?
Which immune response mechanism is directly inhibited by some viruses like Epstein Barr Virus?
Which immune response mechanism is directly inhibited by some viruses like Epstein Barr Virus?
What is the primary function of Cytotoxic T Lymphocytes (CTL) in combating viral infections?
What is the primary function of Cytotoxic T Lymphocytes (CTL) in combating viral infections?
Which molecule do infected cells display to signal their infection to Cytotoxic T cells?
Which molecule do infected cells display to signal their infection to Cytotoxic T cells?
What role does perforin play in the activity of Cytotoxic T Lymphocytes?
What role does perforin play in the activity of Cytotoxic T Lymphocytes?
What is the function of granzymes in the immune response?
What is the function of granzymes in the immune response?
Which cytokine is released by Cytotoxic T Lymphocytes to drive Th1 responses?
Which cytokine is released by Cytotoxic T Lymphocytes to drive Th1 responses?
Why are antibodies noted as insignificant for anti-viral immunity in certain contexts?
Why are antibodies noted as insignificant for anti-viral immunity in certain contexts?
What is true about the cells that Cytotoxic T Lymphocytes kill?
What is true about the cells that Cytotoxic T Lymphocytes kill?
Which action best describes the activation of Cytotoxic T cells once they recognize an antigen on MHC class I?
Which action best describes the activation of Cytotoxic T cells once they recognize an antigen on MHC class I?
What mechanism allows viruses to continuously change their surface antigens to evade the immune system?
What mechanism allows viruses to continuously change their surface antigens to evade the immune system?
Which virus is associated with a protein that inhibits antigen processing?
Which virus is associated with a protein that inhibits antigen processing?
What occurs when cells down-regulate MHC class I molecules?
What occurs when cells down-regulate MHC class I molecules?
Which of the following best describes antigenic shift?
Which of the following best describes antigenic shift?
What is a consequence of antigenic drift in influenza viruses?
What is a consequence of antigenic drift in influenza viruses?
Which method is employed by some viruses to prevent MHC class I from reaching the cell surface?
Which method is employed by some viruses to prevent MHC class I from reaching the cell surface?
What can be a major immune evasion tactic employed by influenza viruses?
What can be a major immune evasion tactic employed by influenza viruses?
How do viruses like HSV evade the immune response?
How do viruses like HSV evade the immune response?
What often results from the viral genetic variations associated with immune evasion?
What often results from the viral genetic variations associated with immune evasion?
Which type of changes is involved in the process of antigenic drift?
Which type of changes is involved in the process of antigenic drift?
What occurs as a result of Th1 cell activation during an immune response?
What occurs as a result of Th1 cell activation during an immune response?
Which factor can lead to reactivation of Mycobacterium tuberculosis residing in granulomas?
Which factor can lead to reactivation of Mycobacterium tuberculosis residing in granulomas?
What is the primary role of IFN-γ in the immune response?
What is the primary role of IFN-γ in the immune response?
What is a major consequence of Th1 induced macrophage maturation?
What is a major consequence of Th1 induced macrophage maturation?
How does the Th1 response affect antigen presentation?
How does the Th1 response affect antigen presentation?
Which of the following best describes granulomas formed during an immune response?
Which of the following best describes granulomas formed during an immune response?
What effect do Th1 cells have on macrophages?
What effect do Th1 cells have on macrophages?
What role do granulomas play in relation to Mycobacterium tuberculosis?
What role do granulomas play in relation to Mycobacterium tuberculosis?
What is the effect of IL-12 in the context of Th1 cell differentiation?
What is the effect of IL-12 in the context of Th1 cell differentiation?
What is one key function of macrophage activation by IFN-γ?
What is one key function of macrophage activation by IFN-γ?
What is a key challenge posed by viruses in relation to the immune system?
What is a key challenge posed by viruses in relation to the immune system?
Which aspect of the innate immune response is primarily activated in response to viral infections?
Which aspect of the innate immune response is primarily activated in response to viral infections?
How do Type I interferons primarily contribute to the immune response?
How do Type I interferons primarily contribute to the immune response?
What is a significant result of viruses developing strategies to evade the immune system?
What is a significant result of viruses developing strategies to evade the immune system?
What defines the innate immune response during viral infections?
What defines the innate immune response during viral infections?
What is the primary goal of the immune system when dealing with extracellular pathogens?
What is the primary goal of the immune system when dealing with extracellular pathogens?
Which immune cells primarily respond to helminth infections?
Which immune cells primarily respond to helminth infections?
What immune response is commonly associated with intracellular bacteria?
What immune response is commonly associated with intracellular bacteria?
What immune response mechanism is crucial in combating viral infections?
What immune response mechanism is crucial in combating viral infections?
Which component is not typically involved in the immune response to extracellular bacteria?
Which component is not typically involved in the immune response to extracellular bacteria?
What is the primary effect of type I interferons (IFNs) on infected cells?
What is the primary effect of type I interferons (IFNs) on infected cells?
Which of the following effects is NOT associated with the action of type I interferons?
Which of the following effects is NOT associated with the action of type I interferons?
Which immune cells are enhanced in response to type I interferons, contributing to the anti-viral response?
Which immune cells are enhanced in response to type I interferons, contributing to the anti-viral response?
What role do RIG-I receptors play in viral recognition?
What role do RIG-I receptors play in viral recognition?
How do type I interferons influence the activity of dendritic cells?
How do type I interferons influence the activity of dendritic cells?
Which of the following statements about Natural Killer (NK) cells is correct?
Which of the following statements about Natural Killer (NK) cells is correct?
What is the role of MHC class I molecules in the immune response to viral infections?
What is the role of MHC class I molecules in the immune response to viral infections?
Which of the following is a consequence of type I interferon action on neighboring uninfected cells?
Which of the following is a consequence of type I interferon action on neighboring uninfected cells?
What is the primary function of antibodies in fighting viral infections?
What is the primary function of antibodies in fighting viral infections?
Which immune cells play a crucial role in eliminating virally-infected cells?
Which immune cells play a crucial role in eliminating virally-infected cells?
Which cytokine is primarily associated with antiviral activity in response to viral infection?
Which cytokine is primarily associated with antiviral activity in response to viral infection?
What is the major outcome for viruses that successfully evade the host immune response?
What is the major outcome for viruses that successfully evade the host immune response?
What effect does antigenic drift have on the influenza virus?
What effect does antigenic drift have on the influenza virus?
How do viruses like Epstein Barr Virus inhibit the immune response?
How do viruses like Epstein Barr Virus inhibit the immune response?
What is the role of perforin in the immune response?
What is the role of perforin in the immune response?
What is the significance of cytokine release by Cytotoxic T Lymphocytes (CTLs)?
What is the significance of cytokine release by Cytotoxic T Lymphocytes (CTLs)?
What strategy do viruses employ to ensure their survival against the immune system?
What strategy do viruses employ to ensure their survival against the immune system?
Which of the following is a characteristic of the innate immune response to viral infections?
Which of the following is a characteristic of the innate immune response to viral infections?
Which factor best explains why type I interferons are crucial in the innate immune response?
Which factor best explains why type I interferons are crucial in the innate immune response?
What is a consequence of viruses down-regulating MHC class I molecules on infected cells?
What is a consequence of viruses down-regulating MHC class I molecules on infected cells?
Which of the following describes a method by which viruses evade the immune response?
Which of the following describes a method by which viruses evade the immune response?
What is the primary role of Natural Killer (NK) cells in antiviral immunity?
What is the primary role of Natural Killer (NK) cells in antiviral immunity?
Which mechanism allows viruses to effectively evade the immune system?
Which mechanism allows viruses to effectively evade the immune system?
How do cytotoxic T lymphocytes (CTLs) identify their target cells?
How do cytotoxic T lymphocytes (CTLs) identify their target cells?
What role do interferons play in the antiviral response?
What role do interferons play in the antiviral response?
What describes the term 'granulomas' in the context of immune response?
What describes the term 'granulomas' in the context of immune response?
What is a significant outcome of type I interferon action?
What is a significant outcome of type I interferon action?
Which function does perforin serve in the immune response?
Which function does perforin serve in the immune response?
What is a key characteristic of the adaptive immune response to intracellular bacteria?
What is a key characteristic of the adaptive immune response to intracellular bacteria?
What distinguishes the immune response to viral infections from that of extracellular infections?
What distinguishes the immune response to viral infections from that of extracellular infections?
What mechanism do viruses typically utilize to inhibit MHC class I expression?
What mechanism do viruses typically utilize to inhibit MHC class I expression?
What is one consequence of type I interferons inducing an anti-viral immune state in infected cells?
What is one consequence of type I interferons inducing an anti-viral immune state in infected cells?
Which immune cell type is primarily activated by type I interferons to target infected cells?
Which immune cell type is primarily activated by type I interferons to target infected cells?
Which innate immune response mechanism directly leads to the increase of antigen presentation across all cells?
Which innate immune response mechanism directly leads to the increase of antigen presentation across all cells?
What receptors are responsible for cytoplasmic recognition of viral RNA during viral infections?
What receptors are responsible for cytoplasmic recognition of viral RNA during viral infections?
How do type I interferons influence dendritic cells (DC) in the context of viral infections?
How do type I interferons influence dendritic cells (DC) in the context of viral infections?
Which response best describes the action of Natural Killer (NK) cells upon recognition of infected cells?
Which response best describes the action of Natural Killer (NK) cells upon recognition of infected cells?
What is the primary function of MHC class I molecules in the context of viral infections?
What is the primary function of MHC class I molecules in the context of viral infections?
What role does the activation of macrophages play in the immune response to viral infections?
What role does the activation of macrophages play in the immune response to viral infections?
Which cells are primarily responsible for combating extracellular bacteria in the immune response?
Which cells are primarily responsible for combating extracellular bacteria in the immune response?
Which immune mechanisms are most associated with the response to helminth infections?
Which immune mechanisms are most associated with the response to helminth infections?
What is the primary goal of the immune system in response to intracellular pathogens such as viruses?
What is the primary goal of the immune system in response to intracellular pathogens such as viruses?
Which immune component is most important in the defense against intracellular bacteria?
Which immune component is most important in the defense against intracellular bacteria?
How do the responses of T H 2 cells differ from those of T H 17 cells in the immune response?
How do the responses of T H 2 cells differ from those of T H 17 cells in the immune response?
What is the primary action of granzymes released by Cytotoxic T Lymphocytes?
What is the primary action of granzymes released by Cytotoxic T Lymphocytes?
What role does IFN-γ play in the immune response against viral infections?
What role does IFN-γ play in the immune response against viral infections?
How do Cytotoxic T Lymphocytes (CTLs) recognize infected cells?
How do Cytotoxic T Lymphocytes (CTLs) recognize infected cells?
What is a key characteristic of the cell killing mechanism used by Cytotoxic T cells?
What is a key characteristic of the cell killing mechanism used by Cytotoxic T cells?
What is the end result of perforin activity during the CTL killing mechanism?
What is the end result of perforin activity during the CTL killing mechanism?
Which statement most accurately reflects the immune response to intracellular infections?
Which statement most accurately reflects the immune response to intracellular infections?
What results when a virally-infected cell presents antigens on MHC class I molecules?
What results when a virally-infected cell presents antigens on MHC class I molecules?
What is the effect of CTLs targeting cells infected by pathogens rather than the pathogens themselves?
What is the effect of CTLs targeting cells infected by pathogens rather than the pathogens themselves?
What is a consequence of Th1 activation on macrophages in response to intracellular bacterial infections?
What is a consequence of Th1 activation on macrophages in response to intracellular bacterial infections?
Which of the following accurately describes the role of granuloma formation in tuberculosis?
Which of the following accurately describes the role of granuloma formation in tuberculosis?
Which cytokine is primarily produced by Th1 cells to activate macrophages?
Which cytokine is primarily produced by Th1 cells to activate macrophages?
What effect does ongoing Th1 response have on the host's health regarding Mycobacterium tuberculosis (MTb)?
What effect does ongoing Th1 response have on the host's health regarding Mycobacterium tuberculosis (MTb)?
What happens to the center of a granuloma over time?
What happens to the center of a granuloma over time?
Which of the following is NOT a function attributed to IFN-γ in macrophage activation?
Which of the following is NOT a function attributed to IFN-γ in macrophage activation?
What is a potential trigger for the reactivation of Mycobacterium tuberculosis from latency?
What is a potential trigger for the reactivation of Mycobacterium tuberculosis from latency?
In what way do Th1 cells enhance macrophage functions?
In what way do Th1 cells enhance macrophage functions?
What best describes the overall result of Th1-mediated immune responses against Mycobacterial infections?
What best describes the overall result of Th1-mediated immune responses against Mycobacterial infections?
Which statement about the immunity developed against completely new viruses created by genetic recombination is true?
Which statement about the immunity developed against completely new viruses created by genetic recombination is true?
Flashcards
Viral pattern recognition receptors
Viral pattern recognition receptors
These receptors detect viruses in the body and trigger an immune response.
Viral capsid proteins
Viral capsid proteins
Proteins on the outside of viruses which can trigger an immune response.
Viral RNA
Viral RNA
RNA from viruses detected by certain immune cells.
Type I interferons (IFNs)
Type I interferons (IFNs)
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MHC class I upregulation
MHC class I upregulation
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NK cells (Natural Killer cells)
NK cells (Natural Killer cells)
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Innate immune response to viruses
Innate immune response to viruses
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Adaptive immunity
Adaptive immunity
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Innate Immune Cells
Innate Immune Cells
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NK Cells
NK Cells
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MHC Class I
MHC Class I
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Viral Infection's Impact
Viral Infection's Impact
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NK Cell Activation
NK Cell Activation
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Killing Mechanism (NK Cells)
Killing Mechanism (NK Cells)
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Receptors on NK Cells
Receptors on NK Cells
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Cytotoxic T Cells (CTLs)
Cytotoxic T Cells (CTLs)
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Perforin
Perforin
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Granzyme
Granzyme
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Cell death/apoptosis
Cell death/apoptosis
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CTL activation
CTL activation
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CTL killing
CTL killing
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What do CTLs kill?
What do CTLs kill?
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IFN-γ
IFN-γ
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Antibodies against viruses
Antibodies against viruses
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Viral Strategies
Viral Strategies
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Immune System's Defense?
Immune System's Defense?
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What type of cytokine do virally-infected cells produce?
What type of cytokine do virally-infected cells produce?
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Which immune cells kill virally-infected cells?
Which immune cells kill virally-infected cells?
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How do antibodies help against viruses?
How do antibodies help against viruses?
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How do viruses evade the immune response?
How do viruses evade the immune response?
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What are the main roles of CTLs?
What are the main roles of CTLs?
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What are the roles of NK cells?
What are the roles of NK cells?
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How do antibodies neutralize viruses?
How do antibodies neutralize viruses?
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What is opsonization?
What is opsonization?
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Viral Genetic Variation
Viral Genetic Variation
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Down-regulating MHC Class I
Down-regulating MHC Class I
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Interfering with Antigen Processing
Interfering with Antigen Processing
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Antigenic Drift
Antigenic Drift
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Antigenic Shift
Antigenic Shift
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NK Cells and MHC Downregulation
NK Cells and MHC Downregulation
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Viral Immune Evasion Mechanisms
Viral Immune Evasion Mechanisms
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How does a virus evade antibodies?
How does a virus evade antibodies?
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What is the outcome of viral immune evasion strategies?
What is the outcome of viral immune evasion strategies?
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How do viruses impact the immune response?
How do viruses impact the immune response?
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TLR3
TLR3
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RIG-I
RIG-I
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Type I Interferons
Type I Interferons
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Induction of Anti-viral Immune State
Induction of Anti-viral Immune State
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NK Cells in Anti-viral Immunity
NK Cells in Anti-viral Immunity
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What cytokines do infected cells produce?
What cytokines do infected cells produce?
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Who fights viral invaders?
Who fights viral invaders?
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How do antibodies work against viruses?
How do antibodies work against viruses?
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What is an immune response escape strategy?
What is an immune response escape strategy?
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What are the roles of CTLs?
What are the roles of CTLs?
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Viral Goal - Survival
Viral Goal - Survival
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Multi-faceted Innate Immune Response
Multi-faceted Innate Immune Response
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Viral Immune Evasion
Viral Immune Evasion
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MHC Class I Downregulation
MHC Class I Downregulation
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Viral Immune Evasion Strategies (Overall)
Viral Immune Evasion Strategies (Overall)
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How do viruses evade antibodies?
How do viruses evade antibodies?
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Outcome of Viral Immune Evasion
Outcome of Viral Immune Evasion
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Extracellular Pathogens
Extracellular Pathogens
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Intracellular Pathogens
Intracellular Pathogens
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Immune System's Goal vs. Extracellular Pathogens
Immune System's Goal vs. Extracellular Pathogens
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Immune System's Goal vs. Intracellular Pathogens
Immune System's Goal vs. Intracellular Pathogens
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What causes new viruses?
What causes new viruses?
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IFN-γ role in MTb infection
IFN-γ role in MTb infection
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Granulomas formation
Granulomas formation
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MTb persistence
MTb persistence
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Factors causing MTb reactivation
Factors causing MTb reactivation
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Importance of ongoing Th1 response
Importance of ongoing Th1 response
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What is a new virus?
What is a new virus?
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Why are new viruses dangerous?
Why are new viruses dangerous?
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How are new viruses created?
How are new viruses created?
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Intracellular Infection
Intracellular Infection
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Innate Immune Response
Innate Immune Response
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Adaptive Immune Response
Adaptive Immune Response
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Interferons (IFNs)
Interferons (IFNs)
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Natural Killer (NK) Cells
Natural Killer (NK) Cells
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Cytotoxic T Lymphocytes (CTLs)
Cytotoxic T Lymphocytes (CTLs)
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Mycobacterium tuberculosis (MTb) Infection
Mycobacterium tuberculosis (MTb) Infection
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NK Cells in Anti-Viral Response
NK Cells in Anti-Viral Response
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Viral Immune Evasion Strategies
Viral Immune Evasion Strategies
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Immune Response to Extracellular Pathogens
Immune Response to Extracellular Pathogens
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Immune Response to Intracellular Pathogens
Immune Response to Intracellular Pathogens
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New Virus
New Virus
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How CTLs Kill
How CTLs Kill
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Antibody Role in Viral Infections
Antibody Role in Viral Infections
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Importance of CTLs in Viral Immunity
Importance of CTLs in Viral Immunity
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Viral Recombination
Viral Recombination
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Reactivation of MTb
Reactivation of MTb
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Ongoing Th1 Response
Ongoing Th1 Response
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Factors Causing Reactivation
Factors Causing Reactivation
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Study Notes
Responses to Intracellular Infections
- Topic of the lecture: Responses to Intracellular Infections
- Presented by: Dr. Patrick Walsh
- Class: Year 1
- Module: BMF
- Date: November 2024
Immunology Lectures Outline
- Barrier Immunity (lecture): Physical, mechanical, and chemical barriers to infection
- Innate Immunity (lecture): Cytokines, inflammation, complement, and antigen presentation
- Adaptive Immunity (lecture): Response to extracellular and intracellular infection (T-cell and B-cell responses)
- Timeline of Immune Response: Instant, minutes/hours, days/weeks
Lecture Learning Outcomes
- Describe a typical immune response to viral infection (using influenza as an example)
- Explain the role of interferons in the anti-viral response
- Define the role of Natural Killer (NK) cells and cytotoxic T cells in antiviral immunity
- Define the adaptive immune response to viral infection
- Describe viral escape from immune detection and disease pathology
- Detail the innate and adaptive responses to intracellular bacteria (using mycobacterium as an example)
- Explain granuloma development and maintenance
Extracellular vs. Intracellular Infections
- Extracellular: Bacteria, fungi, protozoa, helminths (interstitial spaces, blood, lymph, epithelial surfaces)
- Intracellular: Viruses (cytoplasmic or vesicular), bacteria, fungi, protozoa (cytoplasmic or vesicular)
- Different infections require different immune responses
Viral Pattern Recognition Receptors
- Viral capsid proteins: TLR2/6 & TLR4
- Viral RNA (RNA virus): TLR3
- Cytoplasmic RNA receptors: RIG-I
Overview of Immune Response to Intracellular Infections
- Innate immunity: NK cells, Type I IFNs, virus titer,
- Adaptive immunity: Antibodies, virus-specific CTLs
- Timeline of immune responses (days after viral infection)
Innate Immune Response to Viruses
- Type I interferons (IFNs) are produced by infected cells
- Induction of an anti-viral immune state ('shut down' nearby cells)
- Increase in antigen presentation and activation of innate cells (e.g., NK cells, macrophages, dendritic cells)
- Induction of adaptive immunity
Effects of Type I IFNs on Immune Cells
- MHC class I upregulation
- Activation of dendritic cells and macrophages
- Activation of cytotoxic T cells (directly kill infected cells)
- Activation of NK cells (directly kill infected cells)
NK Cells in Anti-viral Innate Immune Response
- NK cells are innate immune cells
- No specific antigen receptor
- Detect "altered self" cells
- Kill virally-infected cells and tumor cells
Mechanism of NK Cells Killing Virally Infected Cells
- Uninfected cells: Express MHC class I, positive signal from inhibitory receptor, NK cells not activated
- Infected cells: Viruses may down-regulate MHC class I, no positive signal from inhibitory receptor, NK cells activated
- NK cells kill infected cells through cytokine production and granule release
NK Cells Mechanism of Action
- Perforin: Forms pores in the target cell membrane
- Granzymes: Enter the pores and trigger apoptosis (programmed cell death)
- IFN-γ: Drives Th1 responses and CTL activity
Antibody Effector Mechanisms Against Viruses
- Neutralization: Antibody prevents adherence (insignificant role in anti-viral immunity)
- Opsonization: Antibody blocks binding and infection (insignificant role in anti-viral immunity)
- Complement activation: Antibody blocks infection of adjacent cells (insignificant role in anti-viral immunity)
Cytotoxic T Lymphocytes (CTL) Activation
- Virally-infected cells display viral antigens on MHC class I molecules
- CTL cells recognize the antigen-MHC complex
- CTL cells release perforin and granzymes to induce apoptosis in the infected cell
Cytotoxic T Lymphocyte (CTL) Killing
- Virally infected cells display viral antigens on MHC class I molecules
- Activated cytotoxic T cells bind the antigen on MHC class I
- CTLs are packed with toxic enzymes
- Perforin forms pores in the target cell membrane
- Granzymes activate apoptosis in the target cell
- CTLs kill infected cells, not the pathogens themselves.
Overview of Immune Response to Intracellular Infections (summary)
- Innate Immunity: NK cells, Type I IFNs, virus titer
- Adaptive Immunity: Antibodies, Virus-specific CTLs
Follow the Influenza Virus Signaling
- Cytokine produced by virally infected cells: IFN-α/β
- Immune cells responsible for killing virally infected cells: CTLs and NK cells
- Role of antibodies against viruses: Neutralization, Opsonization, and Complement activation.
How can Viruses Elude the Host Immune Response?
- Viral genetic variation (mutations)
- Down-regulation of MHC class I molecules
- Interference with antigen processing
- Evasion mechanisms to avoid detection
- New strains produced.
Innate Immune Response to Viruses (summary)
- Viral PRRs activated.
- Type I IFN production and pro-inflammatory cytokines synthesized.
- Multi-faceted innate immune response.
Viruses Strike Back: Evasion Strategies
- Viruses strive to survive in the host environment by evading the immune response.
- Viruses have evolved significant strategies to impede the detection of the virus and IFN production, to withstand immune responses, and ultimately resist infection.
Mechanisms of How Viruses Evade the Immune Response
- Viral genetic variation(Mutations)
- Down-regulate MHC class I molecules.
- Interference with antigen processing.
Mechanisms of Influenza Evasion
- Antigenic drift: Subtle changes in surface antigens (easy adaptation, causing frequent changes in viral strain).
- Antigenic shift: Major changes in viral antigens (caused through genetic recombination).
Other Factors in Immune Evasion and How Influenza Viruses Evade
- Th1 cells are involved in mycobacterial and other intracellular bacterial diseases.
- Th1 induced macrophage maturation results in granuloma formation.
Immune Responses Summary
- Extracellular Pathogens: Goal is to kill the pathogen. Neutrophils, macrophages, Th17, Antibodies, and eosinophils, mast cells, and IgE.
- Intracellular Pathogens: Goal to kill the infected cells. Viruses, NK cells, cytotoxic T cells, and antibody neutralization. Intracellular bacteria, Th1, and IFN-γ.
SGT- A healthy immune response
- XX Nov Immunology tutorial (small groups)
- Pre-read the reference ahead of the tutorial
- Feedback on the lecture content/delivery (using menti.com)
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Description
This quiz focuses on the immune responses to intracellular infections, especially in the context of viral infections like influenza. Students will explore the roles of interferons, Natural Killer cells, and cytotoxic T cells in antiviral immunity, alongside the mechanisms of viral escape from immune detection.
