Parasites use Trojan horse subterfuge to suppress the immunity
of their victims when causing infection, according to a study
funded by the Wellcome Trust.
The finding, which shows a new trick parasites can play, paves
the way to possible treatments for infectious diseases and
allergies.
Scientists at the University of Edinburgh have shown that
parasites are able to secrete tiny sealed packages of genetic
material into the cells of their victims, in order to suppress the
immune response to infection.
The packages, known as vesicles, mimic those that are produced
naturally in most organisms to carry out everyday functions such as
transporting nutrients and chemical messages to and from cells.
The parasite uses vesicles to hide its material inside a
seemingly friendly exterior, like a Trojan horse.
The study was carried out on a parasite found in mice and showed
that the material in the packages is able to interact with the
mouse's own genes.
It manipulates the cell's machinery to suppress products linked
to immunity, so reducing resistance to infection.
The researchers say the discovery could inform new strategies
for treating diseases caused by parasitic worms, which affect
hundreds of millions of people and animals.
The findings also offer a possible way to treat allergies, such
as hayfever, because the immune mechanism that parasites block is
also linked to allergic reactions.
The genetic material from the parasites can also be detected in
human blood, suggesting that this could be used as a test to detect
infection in people.
Ongoing studies are looking into whether other parasites and
viruses use this same strategy.
Dr Amy Buck of the University of Edinburgh said: "We can see for
the first time that parasites can use packages to sneak their
material into the cells of other organisms. We now can develop ways
to target this with implications for the billions of people and
animals at risk of infectious diseases and allergy."
The paper, Exosomes secreted by a nematode parasite transfer small RNAs to
mammalian cells and regulate genes of the innate immune system,
is published in Nature Communications.