Partial anaerobiosis induces infectivity of Leishmania infantum promastigotes.

Leishmania infantum stationary-phase promastigotes could acquire infectivity via preincubation in a partially anaerobic medium (95% air/5% CO2) for 16 h before the infection, whereas promastigotes were efficiently destroyed when no CO2 was present. Incubation of L. infantum promastigotes with additional glucose (20 and 50 mM) greatly increased infection parameters in the absence of CO2; this is consistent with a "reverse Pasteur effect." Results showed that culture at 33 degrees C permitted survival and amastigote multiplication (a nearly 10-fold increase in amastigotes as compared with those observed in 37 degrees C cultures). This finding was obtained with the two strains of L. infantum tested (Doba and PB75).