c601591 at mizzou1.missouri.edu
Thu Aug 3 14:01:34 EST 1995
In article <9508021735.AA24315 at phobos.med.pitt.edu>, bap at MED.PITT.EDU
(Bruce Phillips) wrote:
> There have been several suggestions that the relative nonvariance
> of Ebola Zaire strains over the past 19-20 years reflects an unusually
> stable Ebola-encoded RNA replicase. Without any evidence one way or t'other,
> I think this is very unlikely. As noted RNA replicases have no proof-
> reading attributes. And measurements of RNA replicase error-proneness
> generally show comparatively similar results- i.e., 10-4 to 10-5 mistakes.
> I would be curious in reading about hypotheses wherein certain replicases
> could be 10-100 fold more accurate in their catalysis of polymerization of
> new strands off complementary RNA templates.
> It seems more likely that the stability of Ebola is a reflection of
> selective pressures exerted on the infectiousness of progeny virions. For
> example, capsid conformation requirements or relative constraints on surface
> protein configuration (thus allowing adsorption to otherwise susceptible
> cells) or other characteristics required for virus formation and infectious-
> ness probably play an important role. Finally, the reservoir animal(s)
> whatever their nature and immune system, exert a powerful selective pressure,
> as noted by others.
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