Repost re: possible reservoir for Ebola/Marburg

[Ed Rybicki]

> From:          mfreis at lsumc.edu (Marion Freistadt)
> Subject:       Re: Repost re: possible reservoir for Ebola/Marburg

> You work with RNA and never heard of viroids??
> 
> >> But RNA????  I work with RNA every day and I cant imagine it being
> >> infectious.  RNAses are everywhere and I cant imagine a naked RNA molecule
> >> lasting long enough to be infectious...  Could you give me the Refs. for
> >those > things??
> >> Don
...
> >   I believe your best bet for information on infectious viral RNAs would
> >be to look at work done in picornaviruses.  It has been known for several
> >years that
> >positive stranded RNA viruses can serve as mRNA when transfected into
> >cells. These + RNA genomes can be manipulated in cDNA clones, and then
> >transcribed RNA can be transfected back into cells. Recombinant,
> >infectious virus particles result.  These experiments are not possible
> >with negative stranded RNA viruses since their genomes can not serve as
> >mRNAs.
> >AJ

...and we plant virologists have known for years that many of our 
little charges are highly infectious as naked RNA - if rubbed onto 
plants at sufficiently high concentration (several orders of 
magnitude greater than when using virions) - DESPITE the presence of 
AT LEAST as many / as much RNAase(s) in plants and their environment, 
as around animals.  Comes of not neding specific recognition of cell 
surfaces, as these are hidden under cellulose, and ordinarily 
entering through breaches in the cell wall and membrane.  However, 
all of such viruses are Baltimore Class IV, or ss(+)sense RNA, which 
acts as messenger: and although picornavirus RNA (another Class IV 
virus) is infectious when transfected into cells (see any virology 
textbook), the RNA of Class V viruses - ss(-)sense RNA cviruses, like 
Ebola and influenza and mumps viruses - is not, as it needs to be 
transcribed into mRNA by a virus-coded enzyme before proteins can be made.

 ______________________________________________________
 |     Ed Rybicki, PhD      |  ed at molbiol.uct.ac.za   |
 |    Dept Microbiology     | University of Cape Town |
 | Private Bag, Rondebosch  |   7700, South Africa    |
 |   fax: x27-21-650 4023   | phone: x27-21-650-3265  |
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