Question

Our immune system is so multi-faceted because it has to deal with invading pathogens who have many different invasion strategies. Explain how organisms with each of the following invasion strategies attempt to avoid our immune system. Then state AT LEAST TWO ways our immune system can still protects us against infection by each of them.

A. Bacteria such as Staphylococcus that remain extracellular and disseminate in the blood

B. Bacteria such as Shigella that reside in the epithelial cells within the intestinal tract

C. Bacteria such as Legionella that reside inside Macrophages and block phagosome-lysosome fusion. How would your answer be different if I asked about bacteria such as Salmonella that break out of the phagosome?

D. Bacteria such as Neisseria meningitidis that reside in the blood, but have a thick glycocalyx. When these Gram negative bacteria lyse, they can release endotoxin. Outline the steps by which endotoxin can cause a problem, even if your immune system kills the bacteria.

6. Our immune system is so multi-faceted because it has to deal with invading pathogens who have many different invasion strategies. Explain how organisms with each of the following invasion strategies attempt to avoid our immune system. Then state AT LEAST TWO ways our immune system can still protects us against infection by each of them. L27 L28 A. Bacteria such as Staphylococcus that remain extracellular and disseminate in the blood also L22 B. Bacteria such as Shigella that reside in the epithelial cells within the intestinal tract C. Bacteria such as Legionella that reside inside Macrophages and block phagosome- lysosome fusion. How would your answer be different if I asked about bacteria such as Salmonella that break out of the phagosome? also L22 D. Bacteria such as Neisseria meningitidis that reside in the blood, but have a thick glycocalyx. When these Gram negative bacteria lyse, they can release endotoxin. Outline the steps by which endotoxin can cause a problem, even if your immune system kills the bacteria also L21

Answer 1

• Staphylococci secretes superantigen-like 5 (SSL5) and SSL10 that can inhibit the neutrophil migration toward the site of infection by hindering chemotaxis . They also secret extracellular adherence proteins that can block the adherence of neutrophil ligands to endothelial adhesion receptors. This prevents the neutrophil phagocytosis of the bacteria. The aureolysin secreted by S.aureus inactivates C3 thereby blocking the complement activation and opsonisation.
• Shigella after gaining entry to the macrophage cells, evade from the phagosomes action by escaping to the cytoplasm of the cells, where they reproduce in large numbers and cause sudden cell death. They travel inside the cell by prompting local actin polymerization at one pole of the bacterium (actin based motility). Once Shigella is released form the dead cell, they enter the surrounding cells and repeat the same cycle.
• On uptake by phagocytes, phagosomes containing L. pneumophila avoid fusion with lysosomes instead they quickly with smooth vesicles and are modified into special organelles decked with ribosomes. Once inside the phagosome, the pathogen transfers lipophosphoglycan to the surface of membranes thereby changing the phagosomes’ biophysical properties and preventing fusion with lysosomes .

Following Cell Invasion, Salmonella resides in Salmonella Containg Vacoule (SCV) a unique modified phagosomal compartment. The pathogen develops SIF (Salmonella-induced filaments ) network that can provide aces to nutrients from the microbial cell functioning.

• Neisseria meningitides adhere to and move into the human brain microvascular endothelial cells. The capsule helps in the survival of Neisseria meningitides inside the endothelial cells.

sorry, I dont know the answers to the rest questions.

hope this helps.!