During recent years, sever-al Leishmania infantum genes have been clon
ed and characterized Here, we have summarized the available informatio
n on the gene organization and expression in this protozoan parasite.
Fr om a comparative analysis, the following outstanding features were
found to be common to most of the genes characterized: tandemly organi
zed genes with conserved coding regions and divergent untranslated reg
ions, polycistronic transcription and post-transcriptional regulation
of gene expression. The analysis of chromosomes of L. infantum by puls
ed-field electrophoresis showed the existence of both size and number
polymorphisms such that each strain has a distinctive molecular karyot
ype. Despite this variability, highly conserved physical linkage group
s exists among different strains of L. infantum and even among Old Wor
ld Leishmania species. Gene mapping on the L. infantum molecular karyo
type evidenced a bias in chromosomal distribution of at least, the evo
lutionary conserved genes.