Pre-erythrocytic immunity to Plasmodium falciparum: the case for an LSA-1 vaccine

A vaccine is urgently needed to stem the global resurgence of Plasmodium fa lciparum malaria. Vaccines targeting the erythrocytic stage are often viewe d as an anti-disease strategy. By contrast, infection might be completely a verted by a vaccine against the liver stage, a pre-erythrocytic stage durin g which the parasite multiplies 10 000-fold within hepatocytes. Sterilizing immunity can be conferred by inoculating humans with irradiated pre-erythr ocytic parasites, and a recombinant pre-erythrocytic vaccine partially prot ects humans from infection. Liver-stage antigen-1, one of a few proteins kn own to be expressed by liver-stage parasites, holds particular promise as a vaccine. Studies of naturally exposed populations have consistently relate d immune responses against this antigen to protection.