Dear Colleagues:
My specialty is outside plant pathogens, but I would like to comment that
my personal view is that a plant vector for Ebola is a very likely candidate.
Brucella species have much in common with plant pathogens (they have
megaplasmids or a second chromosome, they secrete a beta-1,2-glucose polymer
and have ribosomal RNA similar to these bacteria)(S. Michaux et al., 1993,
J.Bacteriol. 175:701-705; D.R. Bundle et al., 1988, Infect. Immun. 56:
1101-1106; J.De Ley, 1987, Int. J. Syst. Bacteriol. 37:35-42). It is tempting
to speculate that eons ago a herbivore came along, ate a contaminated plant,
and gave Brucella an opportunity to do a species jump.
As for other pathogens that can do species jumps, all I have on hand are
fungi, rickettsei, and viruses that can go from insects to mammals (J.
Cherwonogrodzky, 1980, Microbial agents as insecticides, Residue Reviews, 76:
73-96) but I seem to recall reading several years ago that some rickettsei can
thrive in plants (citrus tree?), insects (aphids?) and people.
From the above, I have noticed a trend. The more able a microbe or virus
can do a "species jump" and infect a broad range of hosts (i.e. plants,
insects, animals, people), the more it is "bad news" for animals or people.
Possibly if the agent can thrive in any host cell, there is little restricting
or controlling it and hence it is very virulent. The other trend is that at
least one host that although affected by the agents, has evolved some
resistance and is least affected and serves as a reservoir.
In summary, I hope plants as a vector is not a ludicrous concept as its
one I was also considering...John
