Using a new research technology that can reveal how humans develop immunity to malaria, scientists have found that young children under the age of two are the most vulnerable to this parasitic disease. Dr Alyssa Barry from the Walter and Eliza Hall Institute's Infection and Immunity division is using 'protein microarray' technology to screen human blood serum samples for immunity to proteins produced by the malaria-causing Plasmodium falciparum parasite. "We know that one protein, called PfEMP1, that is particularly important for the host immune response can be produced in many different varieties, and these can be altered by the parasite to avoid detection by the immune system," she stated. Dr Barry and colleagues found that in a small region of Papua New Guinea where malaria is endemic, children under the age of two are immune to only a few specific variants of PfEMP1 while older children and adults show immunity to an increasing range of PfEMP1 variants. "Young children are the most vulnerable to malaria," she said. "Our studies show that this is partly because they have not developed immunity to the many different malaria variants to which they are exposed. As people get older, they become immune to a wider spectrum of malaria parasites, and so when they are infected they develop milder disease and eventually do not develop disease at all, although they can still be infected," she explained. Dr Barry said she hoped the research would lead to the development of a diagnostic test for susceptibility to malaria, and also determines which proteins might be the best to use as the basis for a malaria vaccine. The study has been published in the journal Molecular and Cellular Proteomics this month.