iRNA via a virus

[Guest Terence]

Is it theoretically possible to deliver iRNA by a viral vector to supress a particualr gene? Then presumabably the virus would continue to reproduce, thus maintaining gene supression. If the virus was infectious by nature then the gene supression could spread between a number of hosts or a community.

 

I'd better tell you upfront I'm a science fiction writer brainstorming ideas for a novel.

 

Please contribute ANY ideas, however off-the-wall.

 

Thanks,

 

-Terence

[Bryn]

what type of RNA is iRNA when it's at home?

 

Yes it is quite possible to use viruses as vectors. Generally the virus would need to be included in the DNA, and have a promoter associated with it. There is evidance of thousands of viruses in our DNA already that have hitched a ride on us. Most are not expressed but it would be quite possible for a promoter to be assocaited with the virus to express it.

 

There's plenty of research into this ongoing, not sure if anyone has suceeded yet. afaik all the viruses being used loose there infectioness when they are altered to included the DNA that needs to be inserted. But i'm sure it's quite possible, tho very hard. You probably wouldn't get much of a choice about which genes you wanted to surpress, it'd be more luck in getting a viruses that surpresses a gene and is still infectios. By the time we have the skill to produce viruses from scratch that do the job we want the whole point may be rather mute, as with that kinda skill we would be able to alter our DNA willy nilly any way.

[Guest Terence]

Hi Bryn,

 

iRNA, or interference RNA is an exciting development whereby short pieces of of double stranded RNA are used to very specifically target and switch off gene expression. This makes it a powerful experimental tool and potientially a theraputic one. The effect is not fully understood but iRNAs are belived to trigger an antiviral defense mechanism within the cell. Here is a link I found:

 

http://www.imgenex.com/tech_article2.php

 

I know that viruses are used as vectors and presumably this would have to be a double stranded RNA virus (as opposed to a DNA virus). But I have not seen iRNA being used in such a way, although it does seem feasible, as you say. Part of the viral genome would need to be concerned with replication and another part would have to contain iRNAs that can be spliced out in some way. This is where I am on shakey ground with my knowlege.

 

-Terence

 

-Terence

[Skye]

The problem there is that if the iRNA part of the viral genome is spliced out, then the genome won't have these when they are replicated, and the virus particles won't have them when they go onto infect the next cell. As far as I can tell anyway.

 

Another option you might have is to have the virus integrate into the host genome and for the iRNAs to be transcribed by an enzyme that is encoded by the viral genome. There's an added advantage that the integrated virus will have a more permenant effect, I think a single injection of iRNA molecules only knocks out a gene for a few days.