In vitro promastigote fitness of putative Leishmania (Viannia) braziliensis Leishmania (Viannia) peruviana hybrids

In order to initiate studies on the phenotypic properties of hybrids vs, th eir putative parents, the in vitro growth behaviour of promastigotes was co mpared for 15 stocks characterised as Leishmania (Viannia) braziliensis, Le ishmania (Viannia) peruviana and putative hybrids (isolated from the Easter n Andean valley of Huanuco, Peru). Five sets of three stocks, each set incl uding a L.(V.)brasiliensis, a L.(V.)peruviana and a putative hybrid, were c onstituted randomly and counted daily close to isolation from man (ten to 1 8 subcultures). Hybrids and L.(V.)peruviana presented similar growth charac teristics, and they displayed a growth capacity (growth rate and cell densi ty at stationary phase) significantly lower than the one of L.(V.)brazilien sis. Following prolonged in vitro maintenance of one of the sets, the hybri d kept its lower growth capacity. The contrast between the difficulty to gr ow in vitro these putative hybrids, and their high isolation rate from natu ral populations is discussed. (C) 1999 Elsevier Science B.V. All rights res erved.