I've been thinking about the rabies testing problem from an assay point of
view.  First of all, there are only two reasons to kill an animal suspected
of having rabies.  1) In the case of a bite in order to test for rabies so
that that human bitee can be treated.  2) To prevent any other people being
biten by the suspected animal.  Back in the days before there was treatment
for rabies, #2 was the only reason to kill an animal for obvious reasons.
The infected human was already dead anyway since at the time, rabies was
100% fatal to humans.  But by the same logic, if an animal could be isolated
and prevented from biting anyone else, there was no reason to immediatly
kill it since there was no treatment for the bitee anyway.  With the advent
of treatment, reason #1 became more urgent.  The early treatment for rabies
required rapid intervention with a very painfull series of rabies shots.
Thus if the animal was found to be tested negative for the virus, the bitee
could be spared the pain of the vaccine.  Today, since the advent of a less
painful series of vaccines, the issues are different but history colors our
view of rabies.  Too many people died rather horrid deaths for us to be
blase about this illness.  Today, there are only two reasons to kill an
animal that bites a human but is otherwise asymptomatic for rabies.  1) To
spare the human the necessity of taking three rabies vaccine shots at a cost
of ~$200.  2) Because the test for rabies currently requires the examination
of nervous tissue.  To do anyway with reason #1, we would have to pass a law
that requires the bitee to submit to the rabies vaccine.  For obvious
reasons, this will not happen.  So that leaves reason #2 as a point of
attack.  If we had a non-invasive way of testing for the rabies virus, it
seems to me, we could stop all killing of animals (all animals) for testing.
Humans only contract rabies from a bite if the animal is currently shedding
the rabies virus in its saliva correct?  Thus if we had a means of testing
the saliva for rabies virus, we win.  So here is were I come in.  I'm a
molecular biologist that has done alot of PCR (polymerase chain reaction)
PCR amplifies DNA (or RNA, if reverse transcriptase is also used) that is
present in the sample in a DNA sequence specific manner.  It is a very
sensitive test for the presence of DNA of a specific kind.  After the OJ
trial we probably all have a vague idea about how PCR works.  In principle,
what would be required for development of a PCR-based saliva test for rabies
would be (first) a design of DNA primers (short sequence specific runs of
DNA) against the rabies virus genome.  The most efficient test would amplify
all types of rabies virus at the same time.  I'm willing to design the
primers but before I do, I'd like to know alot more about rabies strains,
current test procedures and what kind of research there is out there
currently.  Anyone intersted in helping me with the preliminary research
into the feasiblity of this project, or anyone with ins to the CDC ect.
please e-mail me.
 
Max
[Posted in FML issue 1960]