Gene expression analysis of wild Leishmania major isolates: identification of genes preferentially expressed in amastigotes.

Trying to identify virulence genes of wild Leishmania (L.) major parasites, the species responsible for zoonotic cutaneous leishmaniasis, we compared, using differential display technique, gene expression in two L. major isolates obtained from human lesions and characterized by their contrasting pathogenicity in the BALB/c mouse model. The analysis was performed on amastigotes derived from BALB/c mice lesions. A total of 13 different clones were identified, but the use of reverse transcription and real-time polymerase chain reaction technique did not allow us to confirm any of these clones as differentially expressed. However, the fact that we used the amastigote stage of the parasite led us the identification of amastigote-specific genes, essentially (8 among 13). They are overexpressed, two to seven times, in amastigotes relative to promastigotes. Sequence analysis revealed that two of them namely LPG3 and the ATP dependent RNA helicase correspond to previously described amastigote-specific genes. The others correspond to genes involved in important biological process. Their better characterization could help the development of new drugs targeting the processes in which these molecules are involved.