yoelii (red) interact with CD81 to enter the liver cell, P. However, parasite species differ in which of the pathways they can use. Two proteins on the surface of the liver cell, called CD81 and SR-B1, are used by the parasites to invade the cell. The same two liver cell surface proteins exploited by malaria parasites are also used by the hepatitis C virus to enter human liver cells ( Bartosch et al., 2003). berghei can use both pathways ( Figure 1). The picture that emerged shows that the two species of Plasmodium that infect humans differ in the pathways they use to enter liver cells: P. In the experiments, the parasites attempted to invade a panel of host cells, which had been genetically modified so that they expressed either CD81, SR-B1 or both. Two of these, called Plasmodium falciparum and Plasmodium vivax, infect humans the other two, called Plasmodium yoelii and Plasmodium berghei, infect rodents. – who are based at several institutions in France, Thailand and the United Kingdom – now revisit this question by comparing four different species of malaria parasite. However, previous experiments with different Plasmodium species had yielded contradictory and confusing results. At least two proteins – called CD81 and SR-B1 – on the surface of liver cells are thought to play a role ( Silvie et al., 2003 Rodrigues et al., 2008). How malaria parasites recognise and enter liver cells is poorly understood. However, the liver stage parasites can also be targeted by vaccines. Although the liver phase does not cause malaria (the disease is caused by the parasites replicating inside red blood cells), it is important because it allows some species of Plasmodium to survive unnoticed in the human body for years, in a persistent state that can be difficult to treat. In this way, it can produce enough parasites to overwhelm the immune system once they are released into the blood stream. A single parasite can exploit this niche to grow and divide rapidly. For the first few days of an infection the liver provides a perfect hiding place, being somewhere the parasites can use the plentiful nutrients inside the cells to develop quickly. Inside the body, the parasites first have to find and gain entry to liver cells. Malaria is caused by Plasmodium parasites, which are deposited into the skin through the bites of infected mosquitoes. Now, in eLife, Olivier Silvie of Sorbonne University and colleagues – including Giulia Manzoni as first author – report that they have deciphered some of the code that these parasites use to gain entry into cells in the liver ( Manzoni et al., 2017). The malaria parasite is a type of thief that seeks to exploit the riches of a different hiding place. “Open sesame!” These are the magic words through which Ali Baba and the 40 thieves gain access to a treasure cave.
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