Diabetes as a Co-morbidity for Infectious Disease (16)

Question 1

How is MERS-CoV spread?

Answer 1

Zoonotic: animals -> humans

Bats to camels to humans

Question 2

Severe MERS-CoV is linked to what disease?

Answer 2

Diabetes
Mainly men (most camel herders are men)

Question 3

What steps are involved in a coronavirus replication cycle?

Answer 3

• Spike protein attachment to receptor
• Entry by endocytosis
• Fusion
• RNA replication/transcription
• Protein synthesis
• Endoplasmic-Reticulum–Golgi Intermediate Compartment (ERGIC) assembly
• Exocytosis/release

Question 4

Which human receptor binds to MERS-CoV spike protein?

Answer 4

Dipeptidyl peptidase 4 (DPP4)

Question 5

How was the link between diabetes and MERS-CoV studies in mice?

Answer 5

• DPP4 introduced by genetic manipulation (now susceptible to MERS-CoV infection)
• Mice made diabetic on high fat diet (mainly male mice)
• When infected, they lose weight
• Diabetic mice lost more weight

Question 6

Why do diabetic mice lose more weight after MERS-CoV infection?

Answer 6

Inflammation in the lungs of diabetic mice is more prolonged than normal mice and the inflammatory response is dysregulated in diabetic mice

Lower levels of chemokines in diabetic mice in response to MERS-CoV infection may lead to reduced immune cell recruitment at the early stages of infection

Question 7

How does diabetes lead to other infections?

Answer 7

Immune system is supressed, which allows other pathogens to grow

Glucose rich urine provides a good medium for bacterial growth, for example.

Question 8

How does diabetes relate to COVID-19 infection?

Answer 8

Diabetes does not increase risk of catching the disease (DPP4 is not involved in SARS-CoV-2 entry)

Those with diabetes are more vulnerable to severe illness, may be due to systemic effects of diabetes