Influence of lectin inhibitors on Leishmania major growth and morphology

Gut lectins of the insect vectors play important roles in the transmission of pathogens. Galactosamine, a sandfly midgut lectin inhibitor, was previou sly demonstrated to increase the intensity of Leishmania infection in sandf lies; it was suggested that this was due to the inhibition of sandfly midgu t lectin. However, galactosamine might also enhance Leishmania growth in th e sandfly. Therefore, the aim of this work was to study the effect of galac tosamine and other carbohydrates on Leishmania in vitro. At 50 mM concentra tion, galactosamine inhibits growth of promastigotes, at 10 mM it induces m orphological changes similar to that seen in infected sandflies. Glucosamin e effect is less pronounced, galactose has no effect. This suggests that th e effect of galactosamine on Leishmania differs in vivo and in vitro. Thus, galactosamine does not enhance Leishmania development in sandflies directl y, but rather interferes with some aspect of sandfly physiology (e.g. prote inase and/or lectin activity). (C) 2000 Elsevier Science B.V. All rights re served.