SALIVA OF LUTZOMYIA-LONGIPALPIS SIBLING SPECIES DIFFERS IN ITS COMPOSITION AND CAPACITY TO ENHANCE LEISHMANIASIS

Leishmania donovani chagasi parasites, transmitted by sandflies of the Lutzomyia longipalpis species complex, normally cause visceral leishm aniasis. However, in Central America infections frequently result in c utaneous disease. We undertook experiments to investigate the possible influence of sandfly saliva on the course of infection. Erythemas cau sed by feeding sandflies correlated well with the levels of the erythe ma-inducing peptide, maxadilan, in their saliva. Saliva of Brazilian f lies was the most potent, that of Colombian flies less so, and Costa R ican saliva had very little maxadilan and lacked activity. Nucleotide sequence differences in the maxadilan gene of the three species were d etected by 'single strand conformational polymorphism' electrophoresis . Leishmania infections proliferated fastest when coinjected with the saliva of Costa Rican flies. Brazilian flies had less influence, and C olombian flies only a slight effect. Thus Costa Rican Lutzomyia longip alpis, vectors of non-ulcerative cutaneous disease, have very low vaso dilatory activity and very little maxadilan, but their saliva strongly enhances cutaneous proliferation of Leishmania infections. Conversely , flies from Colombia and Brazil, vectors of visceral disease, have mo re maxadilan, but exacerbate cutaneous infections to a lesser degree. These coincidental observations suggest that species of Lutzomyia long ipalpis differ in their propensity to modulate the pathology of the di sease they transmit.