Pig disease scares capitalists

From ANIMAL PEOPLE, April 1997:

LONDON–– Millions of
dollars invested in genetically engineering
pigs to produce organs for
human transplant may be lost, and
tens of thousands of people desperately
awaiting transplants amid a shortage
of donated human organs may die, if
the biomedical research industry can’t
find a way around PERVs, short for
“pig endogenous retroviruses.”
It may be that pigs will have
to be genetically re-engineered to
eliminate PERVs before engineering
transplantable organs can proceed.
In the March 1 edition of
Nature, neurosurgeon James
Schumacher and colleagues reported
successfully transplanting fetal pig
cells into the brains of 12 patients with
advanced Parkinson’s disease, demonstrating
for the first time that animal
tissues can grow within the human
body. Some patients, Schumacher
said, had experienced relief of
Parkinson’s symptoms for up to two
years after the transplants; all were
improved. The Schumacher team has
now implanted fetal pig cells into the
brains of seven Huntington’s disease
patients, hoping for similar results.


Patience
But in the same edition of
Nature, Clive Patience of the Institute
of Cancer Research in London
announced the discovery of a pig virus
able to infect human cells. Centers for
Disease Control and Prevention regulatory
author Louisa E. Chapman told
Boston Globe science writer Richard
A. Knox that the finding short-circuited
conventional wisdom that pigs
would be a safer source of organs for
transplant than primates. African
green vervets eaten by humans are
believed to have been the source of the
human HIV and Ebola retroviruses.
“We’re not trying to hold
back transplants,” Patience said.
“We’re saying, ‘This is good, but you
have to worry about these things.’ We
have no idea what this could do if it
crossed the species barrier.”
Patience validated warnings
issued for almost a year by Robin
Weiss of the Chester Beatty
Laboratory in London, who isolated
and identified two PERVs, both present
in all domestic swine, and suspected
there were more. One of the
PERVs that Weiss found seemed incapable
of infecting human cells. The
other, though apparently not dangerous
to humans, readily integrates itself
into human cells. “I’ve talked about
this for months at various meetings in
Europe,” Weiss frustratedly told
Laurie Garrett of Newsday last
November. “The companies [developing
pigs as potential transplant
sources] know. They’ve heard it.”
High stakes
The problem, said Weiss, is
that “even if you have a virus that normally
only infects pigs, how long will
it take to adapt to human cells if it sits
around inside of a human as a transplant?
This is especially likely to
occur in these companies’ pigs for
transplant, as they’ve modified the
animals,” replacing key segments of
genetic code pertaining to the pigs’
immune systems, so that humans
won’t reject the pig-grown tissue.
“That just ups the chances of virus
transmission,” Weiss explained.
Similar warnings have been
issued in the U.S. by virologist Jon
Allen of the Southwest Foundation for
Biomedical Research, in San Antonio.
In Britain, the PERV problem
could make permanent the moratorium
on pig organ transplants into
humans issued on January 16 by health
secretary Stephen Dorrell, responding
to concern raised by xenotransplantation
ethics advisory group chair Ian
Kennedy. Dorrell also formed a
Xenotransplantation Interim Regulatory
Authority, chaired by pharmacologist
Lord Habgood, former Bishop of
York, which must issue a permit
before any xenographs may proceed.
A similar ruling took effect in New
Zealand a few days later.
The U.S. Food and Drug
Administration is currently drafting
guidelines for xenography. With the
stakes so high, the pressure is intense,
and at least one major player, U.S.
Surgical, is considered likely to fight
adverse regulation on the legislative
and litigative levels. U.S. Surgical
holds world marketing rights to xenographic
products developed by
Alexion Pharmaceuticals, believed to
be among the firms that are closest to
putting pig-derived organs into the
medical marketplace.

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