Leishmania protozoan parasites cause a diversity of tropical and subtropical diseases, ranging from disseminated visceral infections to disfiguring facial lesions. Ives et al. found that the Leishmania guyanensis parasites that cause mucocutaneous lesions are themselves infected by viruses, which seem to act as the trigger for pathology. The host’s Toll-like receptors 3 and 7 are activated in virus-infected L. guyanensis infections to promote expression of proinflammatory mediators, and the parasites are then able to persist within the inflammatory cells. The viruses might thus offer a tractable target for diagnostic, drug, or vaccine development for a group of widespread but neglected infections.
A. Ives, C. Ronet, F. Prevel, G. Ruzzante, S. Fuertes-Marraco, F. Schutz, H. Zangger, M. Revaz-Breton, L.-F. Lye, S. M. Hickerson, S. M. Beverley, H. Acha-Orbea, P. Launois, N. Fasel, S. Masina, Leishmania RNA virus controls the severity of mucocutaneous leishmaniasis. Science 331, 775–778 (2011). [Abstract] [Full Text]