What bonobo faeces teach us about malaria

21 Aug 2018 | Back to News, Publications and Annual Reports

Malaria parasites are constantly waging war on their hosts. Their objective is to multiply and to jump from host to host – from mosquitoes to human beings. At the same time, the hosts try to protect themselves from the parasite, so as to reduce the symptoms of the disease or prevent falling ill altogether. Scientists have made a very special discovery regarding this protection from malaria parasites.

Every year, nearly half a million people die of the most severe form of malaria, which is particularly prevalent among the poorest people in the world. In addition, there is another form of malaria which tends to be less fatal, but does often cause severe illness. This widespread form of malaria (‘falciparum’) annually causes some 14 million people to fall ill. Malaria is caused by parasites which are transmitted by mosquitoes.

Bonobos are rarely infected with malaria

Scientists have developed methods allowing them to detect malaria parasites in monkey faeces. These methods have allowed us to find several types of malaria parasites in the faeces of gorillas and chimpanzees living in the wild. However, we hardly ever find malaria parasites in bonobo droppings. This is remarkable, because many malaria parasites can be found in bonobo habitats. So how is this possible?

Self or non-self

The answer is very much related to the so-called MHC protein. MHC stands for ‘Major Histocompatibility Complex’ and is part of the immune system. Body cells use these proteins to show which proteins are foreign or part of our own body. In other words, MHC proteins cause the body to be able to recognise pathogens, after which these can be eliminated.

Matter of variation

The more diverse the MHC proteins, the greater the variety of pathogens they will be able to recognise. This helps hosts protect themselves from pathogens. Bonobos seem to have less diverse MHC than chimpanzees, and a particular variant of MHC is found remarkably often in this primate species. This is a type of MHC protein that is also commonly found in humans, particularly in humans who are protected from malaria. So there may be a correlation there.

Good news for humans and bonobos

On the basis of the aforementioned findings, BPRC-affiliated researchers have now published a hypothesis to the effect that this MHC variant, which is commonly found in bonobos, offers protection from malaria. We are unable to examine this hypothesis directly, as bonobos are a protected species.

However, this knowledge does provide us with an excellent guiding principle for follow-up research involving human tissue, as well as vaccine studies involving volunteers. The more we learn about the malaria parasite's weaknesses, the closer we will get to creating a safe and effective vaccine. This development will not only be beneficial to humans, but also to bonobos, our close relatives.