I think that Ebola was always dangerous to man, but it never got in contact
with man to wreak havoc on him until he ran into it somewhere in Africa.
Retroviruses are pretty smart suckers so it does not seem that logical that one
that is not lethal to man would evolve into to something that is lethal. The
former scenario allows the virus to replicate and spread while the latter cuts
the spread of the virus. It is not beneficial to the virus to kill its host, so
it would seem not beneficial for Ebola to evolve from a strain that allows the
host live (thus allowing it to thrive) to a strain that kills its host (which
curtails its ability to replicate).
Who has said that Ebola might have been a plant virus? Was this work published?
Is that "kingdom-jump" been supported at all in literature? I would think it
would be hard for this switch to occur. If this were true, just think about the
myriad of viral diseases we would pick up from other animals alone! I would
think that before we see a plant virus invade humans, that animal viruses would
achieve the switch first. The physical makeup of plants and animals are too
different, in order for Ebola to switch, it needs to run into the same or very
similar virus receptor in humans, come across the same/very similar uncoating
mechanism, integration mechanism, and gene expression mechanism, etc. The
switch is just too gargantuan to imagine. I should know because I tried
targeting a mouse retrovirus to infect human cells for gene therapy purposes
and failed. And that's a animal to animal switch, a mere genus to genus
switch. That's why I can't imagine how a plant virus could switch to become an
animal virus. It just doesn't make sense.
Finally, Paul Bates at UPENN is looking at generating antibodies against Ebola
using a strip-down version of the virus and should be poised to identify the
elusive Ebola receptor. For a more scientific look at Ebola, check out PubMed
in the NCBI site and search for Ebola work that has been peer-reviewed for
publication in the leading journals such as Science, Nature and PNAS.