Ebola vaccine development (or lack thereof)

James T. McKinley mckinley at msupa.pa.msu.edu
Mon May 15 13:51:57 EST 1995


>On Sun, 14 May 1995, James T. McKinley wrote:
>> 
>> Now for a question for the virology types:
>> 
>> Given that Ebola Reston is so close to Ebola Zaire that they are difficult to 
>> tell apart, and that Ebola Reston is apparently harmless in humans, would it 
>> be possible to use Ebola Reston as a vaccine for Ebola Zaire?  I know it 
>> would be hard to test since Ebola Reston kills monkeys just like Ebola Zaire,
>> but if it really came down to it, might it work? 
>[...]


In article <Pine.SOL.3.91.950514230758.4521D-100000 at corona> Patrick O'Neil 
<patrick at corona> writes:

>I am not aware (yet) of research to test this, though it would appear to 
>be obvious to do so.  In any case, it may not work (and if the experiment 
>was tried and failed then it would explain the continued "no treatment" 
>statements) because, for whatever reason, not all vaccinations produce 
>longterm protection.  Sometimes, innoculation with an antigen produces 
>only a very short-lived immune response and no production of memory 
>cells.  This might be the case with the Ebolas.  On the other hand, the 
>antigenicity of Ebola Reston may be sufficiently different from Ebola 
>Zaire that antibodies to the former do not react with latter.

>If it would provide prophylactic protection in monkeys, then it would not 
>matter if normally either virus causes high mortality.  Exposure of 
>Reston monkey survivors to the Zaire strain would quickly tell whether 
>there is any protection across strains.

As is likely obvious from my previous post, I don't know much about virology,
but after posting the above question you replied to, I read an interview with 
Dr. Frederick A. Murphy by Sean Henahan on the WWW about Ebola 
(http://outcast.gene.com/ae/WN/NM/interview_murphy.html) where he asks
Dr. Murphy basically the same question I posted:

#begin quote

Q: Given that there are some signs of natural immunity to Marburg
   and Ebola Zaire, and that the monkey workers were not killed
   after exposure to Ebola Reston,  does this give us any possible
   approaches to vaccine development? Both the measles and rubella
   vaccines were based on attenuated viruses.

A: No, I don't think so. I don't think we would know how to select 
   a stable, safe attenuated virus. The kind of research needed to 
   develop a modified live virus vaccine simply could not be done 
   given the scope of the problem. That is, you only have a
   few people working in labs who would need to be vaccinated, and
   you might want a vaccine stockpile in the event of an epidemic,
   but these are not the scale of circumstances where we could
   afford to develop a vaccine. A killed vaccine is much simpler to
   develop, but so far this has not worked with Ebola virus.

#end quote

Dr. Murphy's reply sounds as if it is mostly a question of money to
develop a vaccine for Ebola, and that given how few people are killed by 
Ebola each year, it's not worth it to those who hold the purse strings 
(the US government I guess), too bad for the folks in Zaire.  I guess the
same applies to the dengue virus and others closer to home. 

                                                                      Jim



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