In article <3v5ual$egh at cisunix1.dfci.harvard.edu>,
york at mbcrr.dfci.harvard.edu (Ian A. York) wrote:
> In article <3v40i0$o2b at grape.epix.net> Dave Peters <dpeters> writes:
> >I've been wondering....
> >Could the Reston form of Ebola somehow be the key to a vaccine for the
> >deadly Ebola Zaire virus? Edward Jenner used the cowpox virus to make a
> >vaccine for the similar smallpox virus. Could the Reston form of Ebola
> >that does not affect humans somehow be used to vaccinate people against
> >Ebola Zaire? Please post your comments.
>> It's not a completely wild idea, but it's unlikely to work. We had a
> disucssion about this some time ago. To summarize that argument, there
> is no guarantee that it will work, and because of the problems in finding
> a valid experimental system, it's not testable yet. I also remember
> reading somewhere (sorry, my mind is melting in the heat and I can't
> remember where) that there is some suggestion that Ebola (like Dengue)
> has antibody-mediated enhancement of infection and so Reston accination
> might actually make things worse. Again, without a good experimental
> system thsi is all guesswork; and the risks of a bad guess are terrible.
There was a posting on the PROMED list recently where the results of this
type of experiment were reported in a recent meeting.
The experiments were done at USAMRIID:
4 monkeys were infected with Ebola Reston. 3 of the 4 died. The
remaining monkey was challenged with Ebola Zaire (I don't know the
substrain, but probably Mayinga). That monkey came down with disease
FASTER than previously uninfected monkey controls.
The conclusion was that previous infection with Reston resulted in immune
enhancement so that the subsequent infection was more severe. I agree
that there was enhancement, but i don't think that they have proven an
immunological connection with this experiment, as many other antiviral
functions could have been impaired by infection with Reston.
This is not exactly like what Dave Peters suggests, because the experiment
was done in monkeys, which may be the prefered host of Reston. Abortive
infection in human beings by Reston may provide better protection against
infection with Zaire, but I agree that the experiment is not do-able
(...or do we have some volunteers?)