Winter - Classical MileEnd Alpacas

From
Dromedary
to Drugs
Could a unique type of antibody found
in the blood of camelids hold the key to
unlocking cures for many dibillitating
human diseases ?
Henry Nichols reports on the success of
current research
Discovery
In the late 1980s, Belgian immunologist
Raymond Hamers, then at the Free
University of Brussels (VUB), found
himself confronted by a couple of bold
undergraduates. The practicals for their
course were just too predictable, they
complained. Could he find them an
original research question to answer?
Hamers remembered half a litre
of camel serum sitting in a freezer.
Although he had it stashed away for
some ongoing research into sleeping
sickness, he reckoned he could spare a
bit for his students to play around with.
"Why don't we see if we can purify camel
antibodies?" he asked.
The results were so unexpected the
students were flummoxed. For a time, so
too was Hamers. The diffusion pattern
of antibodies isolated from the serum
suggested that in addition to the type of
antibody found in all other vertebrates,
the camel also produced a smaller and
entirely novel variety.
They went on to demonstrate this
immunological phenomenon is not just
limited to the dromedary. Other camelids
– the Bactrian camel, llama, alpaca,
guanaco and vicuña – also have the same
resilient slimline antibodies.
In the scorching heat in the heart of downtown Dubai, a herd of dromedary
camels is chewing the cud. These majestic beasts, owned by Sheikh
Mohammed bin Rashid Al Maktoum, are living it up in retirement at the city's
Central Veterinary Research Laboratory. But their lives are far from over. In fact,
these animals could be behind something of a medical revolution.
A chance discovery in the late 1980s revealed that camelids have an extraordinary
immune system unlike that of any other mammal: in addition to normal antibodies,
their blood also contains a miniature variety. Belgian immunologists are working
with the Sheikh's dromedarys to isolate and use these small antibodies as the basis
for 'nanobodies' – tiny proteins about one tenth the size of conventional antibodies
but capable of the same defensive skills.
Nanobodies are so exciting because they can get to parts of the body conventional
antibodies cannot reach. They are less prone to destruction by enzymes and it's
possible they could even be taken in tablet form rather than by injection. Since they
are far simpler than larger antibodies, they are much easier to manufacture and
hence cheaper. The results of the first nanobody-based therapy to enter clinical
results are expected soon.
Antibodies are a key component of the vertebrate immune system, chunky Y-
shaped proteins let loose in the bloodstream or tethered to immune cells. They
are designed to bind to a specific target on a foreign object and bring about its
destruction. In the mid-1970s, scientists worked out how to manufacture these
cunning little proteins in the laboratory. The ability of these so-called 'monoclonal
antibodies' to bind to a target of choice gave them a serious advantage over
conventional drugs, which are not particularly specific and can have all sorts of
side-effects.
But 30 years on, there are only around 20 therapeutic antibodies on the market,
largely because making them is a lengthy and expensive procedure. This has fuelled
a demand for molecules with antibody-like properties that perform as well but are
structurally simpler. Camels and their relatives might offer the solution.
The arms of a conventional antibody are made from two complimentary peptide
32 Alpaca World Magazine Winter 2007 / 08