Characterization of cell cultures derived from Lutzomyia spinicrassa (Diptera: Psychodidae) and their susceptibility to infection with Leishmania (Viannia) braziliensis

Background: The sand fly Lutzomyia spinicrassa (Morales, Osorno-Mesa, Osorno & de Hoyos, 1969) is a vector of Leishmania (Viannia) braziliensis, an etiological agent of cutaneous leishmaniasis in Colombia. The present arficle describes, for the first time, the morphological, karyotypical, and isozymatic characteristics of cell cultures derived from L. spinicrassa embryonic tissues as well as the interaction of L. braziliensis with these cell cultures. Materials/Methods: L. spinicrassa embryonated eggs and neonate larvae were taken for tissue explants. These were seeded in Grace, L-15, Grace/L-15, MM/VP12, and MK/VP12 culture media. The pH range in these media was 6.7 to 6.9 and the cultures were incubated at 28 degrees C. The MHOM/CO/86/CL250 strain of L. braziliensis was used for experimental infection of cell cultures of L. spinicrassa. Results: Cell growth was achieved in L-15 medium and a confluent monolayer was obtained 180 days after the embryonated eggs were explanted. The cell morphology of the pfimary cell cultures was initially heterogeneous, but in the confluent monolayer of these cell cultures and in the subcultures the predominant cell types were later fibroblast-like and epithelial-like. Cultured cells were predominantly diploid (2n=8); however, significant percentages of aneuploids were also recorded. The cell culture isozyme patterns of L. spinicrassa coincided with pupae samples from the same species. Promastigote forms of L. braziliensis could invade cells and transform into amastigote-like forms inside them. Conclusions: The characteristics of cell cultures derived from L. spinicrassa embryonic tissues were determined. These cultures emerge as a new model to study the life-cycle of L. braziliensis.