A Novel Method of Vaccination Using Parasite Membrane Antigens

Abstract

There have recently been a large number of vaccination studies using mouse models of cutaneous leishmaniasis. These have tended to use either whole attenuated organisms (Howard et al, 1982; Liew et al, 1985) or crude antigen preparations (Liew et al, 1985). Although these vaccine preparations increased resistance if inoculated intravenously (i.v.) or intra-peritoneally (i.p.), they exacerbated infections if administered subcutan-eously (s.c). Intravenous or i.p. vaccination procedures are obviously not acceptable for use with humans. Ideally a vaccine should comprise a purified biochemically defined antigen administered by a cutaneous or intramuscular route without any risk of exacerbating naturally acquired infections. Two antigens have been suggested as potential candidates for successful vaccination, the plasma membrane glycoprotein gp63 and the glycocon-jugate excreted factor (EF). Both antigens are involved in the attachment of the parasite to its host cell, the macrophage (Handman & Goding, 1985; Russell & Wilhelm, 1986), and are found in related forms in all species of Leishmania examined to date (Etges et al, 1985; Colomer-Gould et al, 1985; Handman et al, 1984). We describe here a novel means of presenting these antigens to the immune system and we have successfully vaccinated mice against L.mexicana by the s.c. route.