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BSE versus Creutzveld-Jacobs-syndrome

bhjelle at unm.edu bhjelle at unm.edu
Sun Mar 31 18:21:44 EST 1996


In article <ns10005-3003961715450001 at mac17.vet.cam.ac.uk>,
Nigel Smith <ns10005 at cam.ac.uk> wrote:
>In article <4jhafv$1dpq at pegasus.unm.edu>, bhjelle at unm.edu wrote:
>
>> of BSE. In the laboratory, BSE has been transmitted to mice,
>> goats and sheep via the oral route (see http://www.airtime.
>> co.uk/bse/tse.htm.#immunity). BSE can be transmitted into
>> transgenic mice bearing human PrP and produces human PrPSc.
>
>Well, from that link:

(quote deleted)
>
>So, not a mention of an oral route there, then.
>IIRC, the *test* for BSE requires direct injection into a mouse, since the
>is no contagion via the oral route.

Sigh. I'll give you a more direct link to the statements 
and some references.

http://www.airtime.co.uk/bse/tse.htm.#bse.

references: Annals NY Acad Sci 1994; pg 300 (sorry,
forgot to write down volume number).

J Gen Virol 1994 vol 75, 2151 (experimental oral
transmission of BSE to mink). I'm not an expert on
mammalian evolution, but I would speculate that
there is about as much difference between a cow
and a mink as there is between a cow and a man.
The point is that BSE can cross some rather substantial
species boundaries (by oral route), from ruminants into 
animals of the orders Carnivora and Rodentia.
Given that humans and
apes are well-known to be subject to spongiform
encephalopathy, is it so amazing that oral
transmission can also occur between cattle and
primates?


>> As for the risk from sheep and pigs, I would say that if
>> we had 160,000 cases of scrapie in sheep or porcine
>> spongiform encephalopathy, it should be regarded with the
>> same concern as the bovine epidemic.
>
>Scrapie has been endemic in sheep around the world for more than 200
>years. I would be *very* surprised if there hadn't been 160,000 cases by
>now.

Since scrapie disease is very poorly reported and
its incidence is largely unknown, that becomes a very
uncontestable statement. However, even if there have
been 160,000 cases over 200 years (very doubtful),
how does that compare to 160,000 cases over 10
years in a very small area of the world? Answer:
it doesn't. 

Just a reminder: 90% of human CJD is "sporadic". If
10 or 100 cases were actually caused by eating contaminated
sheep, who would be the wiser?
 
>> I would challenge you to convince me that the operation of
>> slaughterhouses could be modified to prevent low-level
>> contamination of meat with neural tissue, and still have
>> an economically viable operation.
>
>And I challenge you to find any record of any contamination in meat for
>sale. There has not been a single case where joint of beef has been found
>to contain the prions believed to be the agent of transmission.
>
Again, a very easy statement to make and hard to
refute. There is no DNA or RNA in the prion, so some
of the most sensitive methods available (PCR, LCR, etc)
are not available. Infected animals do no raise antibodies
in the course of disease. No tissue culture isolation
has any significant sensitivity. This is all *very*
similar to what we had available to detect HIV in
the early days of transfusion-associated AIDS (1983-
1984).

What is "joint of beef" anyway?

Brian



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