Cell surface carbohydrates and in vivo infectivity of glucantime-sensitive and resistant Leishmania (Viannia) guyjanensis cell lines.

The cell surface plays an important role in the interaction of parasites with their hosts. Drug resistance in the protozoan Leishmania may involve changes in cell-surface composition, although it is not known whether infectivity is also affected. One sensitive and two glucantime-resistant lines of Leishmania (Viannia) guyanensis previously isolated were inoculated into hamsters. The sensitive line caused the disease to manifest earlier than the resistant lines. Imprinting analyses of infected macrophages showed that the sensitive line was more infective than the resistant cell lines. In vitro drug resistance was evaluated and the comparative analyses of dose-response curves showed that the susceptibility pattern of the sensitive line did not change after passage in animals, but a decrease in drug resistance was observed in resistant cell lines recovered from the mammalian host. Cell surface carbohydrates of sensitive and resistant cell lines were analysed before and after passage in animals by agglutination tests with several plant lectins. Passage in animals changed the agglutination pattern for many lectins from all three cell lines. Loss of reactivity to lectins seemed to be correlated with a decrease in infectivity of the parasite-resistant cell lines. This study opens possibilities for exploring the relationship between drug susceptibility, infectivity and surface carbohydrate composition of protozoan parasites.