A new study has revealed that malaria parasites are able to outwit the host’s immune system.
Malaria is caused by a parasite, which is injected into the bloodstream from the salivary glands of infected mosquitoes. There are different species of parasite, but the most dangerous is the Plasmodium falciparum parasite, which contributes for 90% of deaths from malaria.
The malaria parasite infects healthy red blood cells, where it reproduces. The P. falciparum parasite produces a family of molecules, called PfEMP1, that are inserted into the surface of the infected red blood cells. The cells become sticky and stick to the walls of blood vessels in tissues. This not only stops the cells being flushed through the spleen, where the parasites would be obliterated by the immune system of the body, but also restricts blood supply to important organs. Each parasite has ‘recipes’ for about 60 different types of PfEMP1 molecule in its genes.
The life cycle of Plasmodium
However, the exact recipes vary from one parasite to the other. Hence every new infection may hold a set of molecules that the immune system has not earlier come across. Dr George Warimwe and team from the Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme and the Wellcome Trust Sanger Institute, have revealed that the parasites get used to their molecules depending on which antibodies it meets in the host’s immune response. They have also found proof to suggest that there may be a limit to the number of molecular types that are actually linked with severe disease.
The researchers examined malaria parasites in blood samples from 217 Kenyan children with malaria. They discovered that a group of genes coding for a particular class of PfEMP1 molecule known as Cys-2 was inclined to be switched on when the children had a low immunity to the parasite; as immunity grows, the parasite switches on a different set of genes, efficiently disguising it so that immune system cannot clear the infection.
Dr Peter Bull from the KEMRI-Wellcome Trust Programme and the University of Oxford, who headed the research, said that the studies could propose a new approach to combating malaria, in terms of both vaccine development and drug involvement. The finding has been published in the journal Proceedings of the National Academy of Sciences.
Source: India-Server
More information: http://www.sciencedaily.com/releases/2009/11/091130151325.htm
