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Questions and Answers
What is the primary cause of tissue damage in HBV and HCV infections?
What is the primary cause of tissue damage in HBV and HCV infections?
- Direct damage to hepatocytes by the virus
- Immune response to infected liver cells (correct)
- Presence of viral particles in the liver
- Cytopathic effects of the virus
What role do granulomas play in tuberculosis infections?
What role do granulomas play in tuberculosis infections?
- They allow the bacilli to spread more easily.
- They stimulate an increase in T-cell count.
- They enhance the replication of the bacilli.
- They prevent the spread of bacilli while causing tissue damage. (correct)
What mechanism do pathogens use to evade the host's adaptive immune response?
What mechanism do pathogens use to evade the host's adaptive immune response?
- Inducing a robust phagocytic response
- Enhancing cytokine production
- Promoting neutrophil activation
- Antigenic variation (correct)
Which condition is associated with the formation of immune complexes in the kidneys?
Which condition is associated with the formation of immune complexes in the kidneys?
Which microbe is mentioned as being associated with cancer due to its role in chronic inflammation?
Which microbe is mentioned as being associated with cancer due to its role in chronic inflammation?
In inflammatory bowel disease, which event is considered critical to the development of inflammation?
In inflammatory bowel disease, which event is considered critical to the development of inflammation?
What is a primary method by which microbes resist phagocytosis?
What is a primary method by which microbes resist phagocytosis?
Which of the following best describes the relationship between chronic inflammation and cancer development?
Which of the following best describes the relationship between chronic inflammation and cancer development?
Which of the following mechanisms do viruses use to evade the immune system?
Which of the following mechanisms do viruses use to evade the immune system?
What type of inflammation is primarily observed in infections caused by pyogenic bacteria?
What type of inflammation is primarily observed in infections caused by pyogenic bacteria?
What is the hallmark of infections with Mycobacterium tuberculosis?
What is the hallmark of infections with Mycobacterium tuberculosis?
In primary tuberculosis, what is Gohn's Focus characterized by?
In primary tuberculosis, what is Gohn's Focus characterized by?
Which type of mycobacteria is primarily associated with abdominal tuberculosis?
Which type of mycobacteria is primarily associated with abdominal tuberculosis?
What typically occurs in the hilar lymph nodes during primary tuberculosis?
What typically occurs in the hilar lymph nodes during primary tuberculosis?
Which type of inflammation is characterized by mononuclear cell infiltrates?
Which type of inflammation is characterized by mononuclear cell infiltrates?
Which of the following describes the modulation of surface structures by pathogens?
Which of the following describes the modulation of surface structures by pathogens?
What is the primary stage of syphilis characterized by?
What is the primary stage of syphilis characterized by?
Which of the following modes of transmission is NOT associated with syphilis?
Which of the following modes of transmission is NOT associated with syphilis?
How long can the tertiary stage of syphilis last?
How long can the tertiary stage of syphilis last?
Which organs are primarily affected during the tertiary stage of syphilis?
Which organs are primarily affected during the tertiary stage of syphilis?
Which lesion is associated with the secondary stage of syphilis?
Which lesion is associated with the secondary stage of syphilis?
How does M.tuberculosis evade the immune response during phagocytosis?
How does M.tuberculosis evade the immune response during phagocytosis?
What role does the carbohydrate capsule play for bacteria causing pneumonia or meningitis?
What role does the carbohydrate capsule play for bacteria causing pneumonia or meningitis?
Which bacteria are known for using the inside of cells as a hideout to escape immune response?
Which bacteria are known for using the inside of cells as a hideout to escape immune response?
What is the consequence of inflammasome activation in innate immunity?
What is the consequence of inflammasome activation in innate immunity?
How do some viruses inhibit the action of interferons during viral infections?
How do some viruses inhibit the action of interferons during viral infections?
Which virulence mechanism do Yersinia and Salmonella employ to avoid inflammation?
Which virulence mechanism do Yersinia and Salmonella employ to avoid inflammation?
What effect do DNA viruses like HSV, CMV, and EBV have on CD8+ cytotoxic T cells?
What effect do DNA viruses like HSV, CMV, and EBV have on CD8+ cytotoxic T cells?
What is one way that Legionella escapes destruction in macrophages?
What is one way that Legionella escapes destruction in macrophages?
What is the primary cause of tissue damage in secondary tuberculosis?
What is the primary cause of tissue damage in secondary tuberculosis?
Which organ is least commonly affected by secondary tuberculosis granulomas?
Which organ is least commonly affected by secondary tuberculosis granulomas?
Which of the following statements about primary tuberculosis is true?
Which of the following statements about primary tuberculosis is true?
In what way can secondary tuberculosis be triggered?
In what way can secondary tuberculosis be triggered?
Which bodily reaction is associated with primary tuberculosis?
Which bodily reaction is associated with primary tuberculosis?
What characterizes the lesions found in secondary tuberculosis?
What characterizes the lesions found in secondary tuberculosis?
Where are granulomas from secondary tuberculosis most commonly found?
Where are granulomas from secondary tuberculosis most commonly found?
Which method of infection is associated with secondary tuberculosis?
Which method of infection is associated with secondary tuberculosis?
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Study Notes
Immune Responses to Microbes
- Inflammation is a complex biological response to harmful stimuli, including infection.
- Immune evasion is a crucial strategy for infectious organisms to proliferate and transmit to new hosts.
- Bacteria, viruses, and fungi employ various mechanisms to evade innate and adaptive immune responses.
Immune Evasion Mechanisms
Antigenic Variation
- Microbes can escape recognition by the immune system through antigenic variation.
Resisting Phagocytosis and Bacterial Killing in Phagosomes
- Many bacteria produce capsules to prevent phagocytosis by neutrophils.
- Mycobacterium tuberculosis inhibits phagosome-lysosome fusion, allowing bacteria to proliferate within macrophages.
- Legionella releases proteins that degrade the phagosome membrane, escaping into the cytoplasm.
Escaping the Inflammasome
- Yersinia and Salmonella use virulence proteins to block inflammasome activation, preventing IL-1 and IL-18 secretion.
Disruption of Interferon Pathways
- Some viruses produce soluble IFN receptor homologues to block IFN signaling or inhibit JAK/STAT signaling.
Decreased T-Cell Recognition
- DNA viruses can interfere with MHC class I presentation, hindering T-cell recognition.
- HIV infects CD4+ T cells, macrophages, and dendritic cells, directly compromising immune function.
Patterns of Host Responses to Microbes
- Neutrophil-rich acute suppurative inflammation: Typical of infections with many bacteria.
- Mononuclear cell infiltrates: Common in chronic infections and some acute viral infections.
- Granulomatous inflammation: Hallmark of Mycobacterium tuberculosis and certain fungal infections.
- Cytopathic and proliferative lesions: Caused by some viruses.
- Necrosis: Result of tissue-damaging toxins produced by microbes such as Clostridium perfringens.
- Chronic inflammation and scarring: Final common pathway of many infections.
Tuberculosis
- Chronic granulomatous disease caused by Mycobacterium tuberculosis, Mycobacterium bovis, and atypical mycobacteria.
Primary Tuberculosis
- Occurs in individuals with no prior immunity.
- Characterized by the formation of a primary complex, including a primary lesion (Gohn's focus) and enlarged hilar lymph nodes.
Secondary (Post-Primary) TB
- Can occur due to reinfection, reactivation of dormant disease, or progression of primary TB.
- Granulomas are often found in the lung apices, kidneys, meninges, and other organs.
- Cavities are a common feature.
Syphilis
- Chronic infective granuloma caused by Treponema pallidum.
Stages of Syphilis
- Primary syphilis: Characterized by chancre formation on the skin or mucous membranes.
- Secondary syphilis: Marked by condyloma lata and widespread skin lesions.
- Tertiary syphilis: May occur 2-10 years after secondary syphilis, involving cardiovascular and central nervous systems.
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