Anti-cancer Chicken Eggs Produced
|
GM
chickens could be a route to faster,
cheaper drugs |
UK
scientists have developed genetically
modified chickens capable of laying eggs
containing proteins needed to make cancer-fighting
drugs.
The
breakthrough has been announced by the
same research centre that created the
cloned sheep, Dolly.
The Roslin Institute, near Edinburgh,
says it has produced five generations
of birds that can produce useful levels
of life-saving proteins in egg whites.
The work could lead to a range of drugs
that are cheaper and easier to make.
Professor Harry Griffin, director of the
institute, told the BBC: "One of
the characteristics of lots of medical
treatments these days is that they're
very expensive.
"The idea of producing the proteins
involved in treatments in flocks of laying
hens means they can produce in bulk, they
can produce cheaply and indeed the raw
material for this production system is
quite literally chicken feed."
Roslin has bred some 500 modified birds.
Their existence is the result of more
than 15 years' work by the lead scientist
on the project, Dr Helen Sang.
But it could be another five years before
patient trials get the go-ahead and 10
years until a medicine is fully developed,
the Roslin Institute cautioned.
Anti-viral approach
Therapeutic proteins such as insulin have
long been produced in bacteria; but there
are some complex proteins that can only
be made in the more sophisticated cells
of larger organisms.
Scientists have successfully made a range
of these molecules in the milk of genetically
modified sheep, goats, cows and rabbits.
The work at Roslin shows it is now possible
to use chickens as "biofactories",
too.
A number of GM animals are now being used
as drug factories
|
Go-ahead
for 'pharmed' goat |
Some of the birds have been engineered
to lay eggs that contain miR24, a type
of antibody with potential for treating
malignant melanoma, a form of skin cancer.
Others produce human interferon b-1a,
which can be used to stop viruses replicating
in cells.
The proteins are secreted into the whites
of the eggs. It is a fairly straightforward
process then to extract and purify them.
Dr Sang said the team was highly encouraged
by the level of the birds' productivity,
but further improvements were required.
"We're probably getting a high enough
productivity if you want to make a very
active protein like interferon, but not
enough yet if you want to make an antibody
because people need large doses of these
over long periods; so one of our next
challenges is to try to increase the yield
in egg white," she told BBC News.
Wider role
Chickens had some advantages over other
animals for "pharming" because
their lifecycles were shorter, said Dr
Sang.
"Once you've made the transgenic
birds, then it's very easy; once you've
got the gene in, then you can breed up
hundreds of birds from one cockerel -
because they can be bred with hundreds
of hens and you can collect an egg a day
and have hundreds of chicks in no time,"
she explained.
The Roslin research is part of the Avian
Transgenic Project, a joint venture with
biotechnology firms Viragen and Oxford
BioMedica.
Details of the latest work are to be published
this week in the US journal Proceedings
of the National Academy of Sciences (PNAS).
The Roslin team also expects its engineered
chickens to provide new insights into
aspects of reproductive biology.
It says the ability to modify birds' embryos
will allow researchers to study fundamental
processes that control the very early
development of vertebrates.
It is just over 10 years since the Finn
Dorset lamb called Dolly was born at the
institute.
She was the first mammal to be cloned
from an adult cell - making her a genetic
replica of a six-year-old ewe. She was
put down in 2003 after contracting a common
lung disease. pizza buffet. Forklift Brands
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