Experimental infection of Leishmania L. chagasi in a cell line derived from Lutzomyia longipalpis (Diptera: Psychodidae)

The present work describes the in vitro infection of a cell line Lulo, derived from Lutzomyia longipalpis embryonic tissue, by Leishmania chagasi promastigotes. This infection process is compared with a parallel one developed using the J774 cell line. The L. chagasi MH/CO/84/CI-044B strain was used for experimental infection in two cell lines. The cells were seeded on glass coverslips in 24-well plates to reach a final number of 2 x 10(5) cells/well. Parasites were added to the adhered Lulo and J774 cells in a 10:1 ratio and were incubated at 28 and 37ºC respectively. After 2, 4, 6, 8, and 10 days post-infection, the cells were extensively washed with PBS, fixed with methanol, and stained with Giemsa. The number of internalized parasites was determined by counting at least 400 cultured cells on each coverslip. The results showed continuous interaction between L. chagasi promastigotes with the cell lines. Some ultrastructural characteristics of the amastigote forms were observed using transmission electron microscopy. The highest percentage of infection in Lulo cells was registered on day 6 post-infection (29.6 percent) and on day 4 in the J774 cells (51 percent). This work shows similarities and differences in the L. chagasi experimental infection process in the two cell lines. However, Lulo cells emerge as a new model to study the life-cycle of this parasite.

Protein Profiles of Trypanosoma cruzi and Trypanosoma rangeli

Trypanosoma cruzi, is a protozoan parasite, which has a close phylogenetic relationship with Trypanosoma rangeli that is not pathogenic for the vertebrate host. Both parasites have antigenic similarity, they have different and complex total protein profiles according to their morphological and physiological stage epimastigotes or trypomastigotes, showing a differential gene expression during the life cycle. There are also differences according to T. cruzi populations used, which were isolated from different geographical areas and were harvested from different sources. This study clearly showed the Colombian SA strain that is highly virulent, has differences in its protein profile when as compared with Dm28c clone, Tulahuen strain and Colombian Astec strain which is not virulent. The proteins were separated by polyacrylamide gel electrophoresis (SDS-PAGE). Specie-specific proteins were found which allow us to identify them, just as it occurs with T. rangeli (Choachí-2V strain), which has three protein bands. However, two of them are not only present in epimastigotes but also in trypomastigotes, but the other is exclusive of epimastigote forms.