Step I Interferon mechanism

[Phloston]

Interferons induce the production of a ribonuclease that degrades viral mRNA while leaving host mRNA unaffected.

What is the mechanism behind this selectivity?

 

[thehundredthone]

Google?

http://pathmicro.med.sc.edu/mayer/vir-host2000.htm

One protein, called 2'5'Oligo A synthetase, is an enzyme that converts ATP into a unique polymer (2'5' Oligo A) containing 2'- 5'phophodiester bonds. Double stranded RNA is required for the activity of this enzyme. The 2'5'Oligo A in turn activates RNAse L which then breaks down viral mRNA. The second protein is an protein kinase that, in the presence of double stranded RNA, is autophosphorylated and thereby activated. The activated protein kinase in turn phosphorylates elongation factor eIF-2 and inactivates it. By the action of these two IFN-induced enzymes protein synthesis is inhibited. Although the infected cell may die as a consequence of the inhibition of host protein synthesis, the progress of the infection is stopped. Uninfected cells are not killed by IFN treatment since activation of the two enzymes requires double stranded RNA, which is not produced. Some viruses have means of inhibiting the antiviral effects of IFN. For example the adenoviruses produce an RNA which prevents the activation of the protein kinase by double stranded RNA thereby reducing the antiviral effects of IFN

http://jem.rupress.org/content/186/6/967.full.pdf

Upon viral infection, double-stranded RNA (dsRNA), apparently derived from viral replication inter- mediates, activates OAS resulting in the production from ATP of an unusual series of short 2��→5��–linked oligoadenylates referred to as 2–5A

 

[Phloston]

Thanks for that.

 

[phd89]

honestly if we have to know that for the exam and it is one that actually counts not just a test question. That is insane! Did this come up in any Qbank?

 

[thehundredthone]

One does not simply walk into a phloston thread (expecting high yield discussion).

 

[ashik33]

One does not simply walk into a phloston thread (expecting high yield discussion)..

Yeah.... and his profile pic says it all. He's smiling at all those who are scratching their head looking at his questions. Good luck to all.

 

[aspiringmd1015]

when do viruses have DS rna?

 

[slz1900]

honestly if we have to know that for the exam and it is one that actually counts not just a test question. That is insane! Did this come up in any Qbank?

There is 0.00% chance that you would need to know this for the exam.

 

[Phloston]

when do viruses have DS rna?

Rotavirus is double stranded segmented. With ten segment. USMLE will sometimes ask which virus can demonstrate genetic modulation similar to influenza. Answer is rota because it's segmented.

 

[Phloston]

There is 0.00% chance that you would need to know this for the exam.

Thanks. I'll retroactively take your advice four years ago. ;-)

 

[teehees]

Very cool to see Phloston around still!

I'm another fan 😀

*desperately tries to think of a question....damn*

 

[slz1900]

Thanks. I'll retroactively take your advice four years ago. ;-)

Related question: how many quarks are in the 4th carbon in propranolol? I need to get a 340 on my step.

 

[worldbeater]

Rotavirus is double stranded segmented. With ten segment. USMLE will sometimes ask which virus can demonstrate genetic modulation similar to influenza. Answer is rota because it's segmented.

In addition to rotavirus being segmented, you can add orthromyxo, bunya, and arena virus "OBAR"

Thanks. I'll retroactively take your advice four years ago. ;-)

lol