Trypanosomes are parasites which have been responsible for a number of epidemics in Africa, in particular sleeping sickness in humans and nagana among cattle. Around 45 million humans and 25 million head of cattle are exposed to these diseases which are transmitted by the bite of the tsetse fly, in which these parasites spend part of their life. Nagana is depriving Africa of over 80% of the livestock that it could potentially produce... Trypanosomes are therefore having a devastating impact on the economy and on public health.
Once the parasite reaches the blood of the mammal, it escapes the notice of the immune system of its host due to the fact that it constantly disguises itself: since almost all of its surface is covered with a protein called VSG -against which the infected organism is able to produce antibodies - it thwarts the defence system by constantly transforming this protein so that the antibodies do not recognize it.
The trypanosome is an excellent model for use in the study of the mechanisms through which parasites are able to adapt to their successive hosts, in particular through antigenic variation, a process whereby the surface components constantly change, throwing the immune system into disarray and preventing the development of a vaccine.
The research of this team has afforded a clearer understanding of the underlying genetic mechanisms of this fascinating phenomenon and has yielded some surprising findings which are currently being used to develop new vaccination strategies.