Ebola Virus Question

John Brunstein brunstei at UNIXG.UBC.CA
Mon Jan 1 14:28:30 EST 1996


	Well, an interesting and perhaps educational question for our 
viewers at home ;-).  You're right in the basic premise, Ron: a vaccine 
is usually (without getting too technical) either a killed but 
immunologically active viral preparation, or a severely weakened 
'crippled' form of the virus in question.  Expose to this nonpathogenic 
species allows for the clonal selection and proliferation of 
epitope-specific B cells, production of memory B cells, and clonal 
expansion of epitope specific T cells.  All of this basically boils down 
to letting the immune system 'see' the pathogen and allowing it to 
customize its defensive repertoire against future infections with the 
same agent (or at least ones with the same epitopes).  {Note: my 
apologies to the immunologists on here for the gross oversimplification!} 
	Anyhow...the theory at this point goes (1) Ebola is a pretty 
nasty virus; (2) A few people were exposed to Ebola Reston strain and did 
not die a gruesome haemorhagic-fever death; (3)  Why not go innoculate 
people with Ebola Reston as a vaccine? Problem solved.....
	Hmmmmm.  Well, let's take a few basic facts in mind.  Ebola has a 
small RNA genome, coding for a handful of proteins of which (in my non-Ebola 
specialist understanding) we can only assign definite functions to a 
few.  Due to the difficulties in dealing with a Level 4 pathogen, the 
virus and its 'lifecycle' are really not very well understood.  Sound 
like a bunch of technical mumbo-jumbo?  Well, the translation of the 
preceeding sentances would be "Ebola is poorly understood.  We don't know 
what is responsible for the virulence or cytotoxicity.  We are not really 
sure what the important differences between the Reston and other strains 
are.  Worst of all, the virus is prone to a rapid mutation rate (a 
conseqence of having an RNA genome)." 
	So......now who's up for injection with Ebola Reston?  We think 
(but aren't sure because we have really no data) that it may have a 
preventative effect.  We think it won't kill you (but we're not sure of 
that, either...we really would need to see hundreds of cases of people 
infected harmlessly with it to have any confidence in THAT statement!).  
Oh yeah, and it's about 98% identical with the strains that kill you in 
one of the quickest and most gruesome ways imaginable...and mutates 
quickly.  Well, MAYBE it won't mutate to a super-virulent strain in 
you...hey, stop squirming, how am I supposed to innoculate you with your 
arm flailing about like that? Nurse!  Stop that guy who just ran out of 
here..he didn't get his vaccination! <sound of smashing glass as 
patient/victim hurls himself through the 4th story window to escape the 
mad doctor with a syringe full of Reston....patient/victim rightly 
assumes this mode of exit is safer than the injection...>.
	Make a little more sense now?  I'm sure that if anyone wanted to 
volunteer for innoculation with Reston followed by exposure to one of the 
other strains, we'd be happy to gather some real data...strange, but I 
don't hear any volunteers...  :-)
	Now, this isn't to say it's all a bad idea.  The basic premise 
DOES have a lot of promise, and I'm sure the lurking Filoviridae people 
on here are doing research on exactly that sort of thing.  If we knew 
what made Reston nonpathogenic, and how to KEEP it that way, it might 
make sense to try as a vaccine.  It would probably just be simpler, 
though, to clone and express a noncytotoxic epitope from the virus and 
use that as a vaccine...again, though, we have the problem of who's going 
to volunteer to have the vaccine tested on them.  
	Well, I hope this answers your question.  Remeber, folks, don't 
try this at home.  We now return to our normally scheduled program (adds 
for pyramid schemes, conspiracy theories, and flaming...)
	Resuming LURK mode <shimmer......blink!>
John Brunstein
Dept. of Biochemistry and Molecular Biology
University of British Columbia

On Mon, 1 Jan 
1996 RGALLA41 at MAINE.MAINE.EDU wrote:

> I am sure someone has thought of this before... but why couldn't Ebola Reston
> be used as a vaccine for Ebola Zaire and Sudan?
> 
> -Ron
> 
> 
> 



More information about the Virology mailing list