Farewell to smallpox virus?

ROBERT COELEN robert at arbo.microbiol.uwa.edu.au
Wed Sep 1 15:17:03 EST 1993


In article <CCLtwt.8z at world.std.com> choupt at world.std.com (Charles E Houpt) writes:
>From: choupt at world.std.com (Charles E Houpt)
>Subject: Re: Farewell to smallpox virus? 
>Date: Tue, 31 Aug 1993 03:34:04 GMT

>masuda at fcs280b.ncifcrf.gov (Michiaki Masuda) writes:
>>   I heard that at ICV, there was a debate concerning the US government policy
>>to collect and destruct all the smallpox virus stocks in the world. Actually,
>>the decision seems to have been already made, and unless there is a strong
>>claim against this policy from someone, there will be no smallpox virion
>>on this planet after Dec. 31 this year.

>This week, New Scientist (a British science magazine) had an editorial
>advocating the extinction of smallpox.  The editorial claimed that
>if we ever needed the virus again, it can be reconstructed from its
>DNA sequence.

The in thing with RNA viruses at the moment is to construct a full length cDNA 
copy of the RNA genome, clone this material into some plasmid vector, fiddle 
with the DNA by way of in vitro mutagenesis and see what the effect of your 
changes are on virus produced from RNA, read of the DNA copy with say T7 RNA 
polymerase and transfected into cells with one of these lipid compounds 
designed to get nucleic acid into cells. In the case of positive stranded RNA 
viruses, this is by and large achievable since:

     (a) the genomes are not very long (about 12Kb max)
     (b) the viral genome RNA functions as messenger RNA and therefore,
         when introduced into the cytoplasm, initiates a round of virus 
         replication, leading to new virions, which are then able to infect 
         other cells.

Whilst many DNA viruses have much larger genomes than RNA viruses, in theory 
it should be possible to reconstruct such genomes. How long it would take and 
how much it would cost is another matter. I would like to hear some comments 
about this from some of the herpes- or poxvirus people who read this


>Is this possible now?  Has anyone actually reconstructed a complete
>virus starting from just a DNA sequence?


Kindest regards,


Robert
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Dr R.J. Coelen                             phone 61 - 9 - 389 3915
Dept of Microbiology                       fax   61 - 9 - 389 2912
University of Western Australia            snail Nedlands, 6009
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