Questions 28-34) You have a mouse parvum, which release model of cryptosporidios
ID: 270189 • Letter: Q
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Questions 28-34) You have a mouse parvum, which release model of cryptosporidiosis, caused by the intracellular Apicomplexan C replicates inside gut epithelial cells. In the mouse, C panum, can replicate, and ysis, with a single cycle lasting approximately 24 hours. Parasite burden over time after introduction of 1000 parasites into the mouse digestive tract shown below. The mice appear d days, followed by a further 5 days in which blood can be found in the in the stool. by oral gavage is sease free until -day10-11, and then are diarrheic for 3-4 0 4 8 12 16 24 Days, post-infection 28) Which of the following statements is a likely and accurate description of the murine acquired immune response to C. parvum based on the diagram? a) Parasite replication is unchecked until an acquired immune response starts to control parasitaemia in the second week of infection. b) All control of parasite load appears to be dependent on an acquired immune response c) Parasite load is very strongly reduced after the onset of an acquired immune response none of the above 29) Which of the following statements is a likely and accurate description of the murine innate immune response to C. parvum based on the diagram? a) Parasite replication is unchecked until an innate immune response starts to control parasite in the second week of infection. 6) Parasite load is quickly cleared by the innate immune response c) Parasite load appears to be unaffected by an innate immune response d) none of the above 30) You hypothesize that Toll-like receptor signaling could be involved in the immune response to C. parvum. You generate a TLR9 knockout mouse(TLR9-/-), and infect the TLR9-/- mice and their wildtype siblings as a control group. The sibling controls display the exact same relationship between parasite load over time as illustrated. The TLR9 -4-mice are diarrheic by day 5, and die from the infection between days 8-10. Loss of TLR9 does not change the relationship between disease pathology and parasite burden. Which of the following statementsExplanation / Answer
28: C, 29: D 30: A
As we can see the pathogen grows, increases in load until it reaches a plateau on third day, hence this is when innate response starts to regulate the pathogen but ultimately fails and the pathogen starts replicating again until acquired immune response kicks in by end of second week and brings down the pathogen. Hence it is th acquired immune response that checks the growth heavily but it would be wrong to say that innate system did not control the pathogen at all.
TLR 9 knockouts die but will witness the control by innate systems hence first plateau will remain, but the plateau between 8-10 days will not be there as there is not acquired immune response to kick in and hence the load will be more than the controls.
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