Section Bank Vol 2 BB #6

Which process is most likely observed in CB3-infected cells?

A Production of high levels of caspases

B Production of new cell membrane

C Replication of intracellular organelles

D Replication of cellular DNA

Passage 1 (7 questions)

An adult individual experiencing diarrhea complained of weight loss despite consuming a large amount of food. Researchers took a biopsy of the pancreas and small intestine, collected a stool sample, and performed a glucose tolerance test (Table 1), where glucose levels are tested under two conditions: after fasting and after 2 hours of consuming 75 g of glucose in 237 mL solution.

Table 1    Results of the Glucose Tolerance Test

|| || |Blood glucose test|Fasting (mg/dL)|After 2 h (mg/dL)| |Standard value|<95|<140| |Results| 135|  210|

Researchers detected glucose in the individual’s urine and meat fibers and fat in the stool. Biopsy of the small intestine confirmed the presence of bile and the pH of 4. Researchers also observed increased levels of bacteria in the large intestine and osmotic diarrhea. The biopsy of the small intestine showed a non-pathological structure, but biopsy of the pancreas showed inflammation. Researchers suggested treatment with supplemental pancreatic enzymes.

Researchers’ analysis of the individual’s pancreas showed that the inflammation was due to Coxsackie-B3 (CB3) virus infection. Coxsackie-B virus is a non-enveloped, positive-sense, single-stranded RNA enterovirus. CB3 enters target cells through the coxsackievirus-adenovirus receptor (CAR) located in intercalated discs and/or the decay-accelerating factor (DAF), which is expressed in epithelial and endothelial cells. The CB3 genome has an open reading frame of approximately 7.5 kb, and the virus uses cellular autophagy to promote replication. If CB3 infection reaches the heart, it could result in arrhythmia due to dysfunction in depolarization and repolarization of the myocardial cells.

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I picked C since autophagy means breaking down damaged organelles so new ones can take their place. The right answer was A but that implied apoptosis. Where did apoptosis come from? How did the cells start dying?