Immune evasion Flashcards
What are the three preformed antimicrobial agents?
Interferons
Complement
Opsonin
What is the innate immune system?
Non-antigen specific, functions on the basis of recognising pathogenic and molecular patterns.
There is no immunological memory conferred through this system.
What are PAMPs?
Diverse set of microbial molecules, whereby general structural and biochemical patterns are shared through pathogen recognition receptors.
Which type of receptors detect PAMPs?
Pathogen recognition receptors (PRR)
Which type of transmembrane proteins located on leukocytes recognise conserves molecules through bacterial structures and viral structures?
Toll-like receptors
What are the examples of bacterial PAMPs? (4)
Flagellum (protein flagellin)
Lipopolysaccharide (Endotoxin)
Peptidoglycan
Glycolipids
What are the examples of viral PAMPs? (3)
Glycoproteins Double stranded (ds) DNA Single stranded (ss) DNA
What type of bacteria is S.aureus?
Gram positive, coagulase and catalase positive
Which type of coagulase bacteria is s.aureus?
Coagulase positive
What is the structure of s.aureus?
Consists of polysaccharide capsule, cell protein A, has catalase, coagulase proteins embedded within coat.
What is the function of the polysaccharide capsule within s.aureus?
Protective against phagocytes
What is protein A?
Clumping factor proteins, mediates adherence of bacteria to host tissues.
What is the function of catalase?
Protects the bacterium from peroxides produced by neutrophils and macrophages
What is the function of coagulase?
Converts fibrinogen to insoluble fibrin resulting in clot formation, protects from phagocytosis
Which enzymes secreted by s.aureus stimulate tissue destruction?
Lipases, nucleases and hyaluronidase
Which cytotoxins lyses erythrocytes, neutrophils, macrophages and host cells?
Cytotoxin, alpha, beta, delta, gamma and leucocidin
Which type of toxins are heat stable and acid-resistant?
Enterotoxins
Which type of toxins cause scalded skin syndrome?
Exfoliative toxins A and B
What is scalded skin syndrome?
The superficial layers of skin peel off
What is a pyogenic?
Pus forming
What two groups of diseases are formed from s.aureus?
Localised pyogenic diseases
Systemic diseases
What are localised pyogenic diseases?
Diseases characterised by tissue destruction mediated by hydrolytic enzymes and cytotoxins
What types of antigens do toxins behave as?
Superantigens
What type of disease is impetigo?
Pyogenic disease; localised skin infection characterised by pus-filled vesicles on a erythematous base.
What type of disease is pneumonia?
Pyogenic
Abscess formation in the lungs, secondary infection succeeding viral infections of the respiratory tract.
What type of pyogenic disease concerns hair follicles?
Folliculitis.
What type of disease are furuncle and carbuncles?
Large pus filled skin nodules progress deeper skin layers and spread into circulation.
Which S.areus pyogenic disease is associated with abscess formation in the lungs?
Pneumonia
What is osteomyelitis?
Bone degradation, primarily in highly vascularized areas of long bones
What is septic arthritis?
Infection of joint regions characterized by a swollen reddened join with an accumulation of pus
What are the three main toxin-mediated diseases of s.aureus?
Toxic shock syndrome
Food poisoning
Scalded skin syndrome
Why does food poisoning occur with s.aueus?
Consumption of heat-stable enterotoxin contamination results in the onset of severe vomiting, diarrhea, and stomach cramps
What is scalded skin syndrome?
Localised infections produce the toxin that traverses into circulation and causes outermost skin layer to blister and peel off