The parasitic protozoan Leishmania is the aetiological agent of a spectrum
of clinical diseases, ranging from disfiguring skin lesions to life-threate
ning visceral infection, and is a serious health problem in tropical and su
btropical areas world-wide. Leishmania parasites undergo a dramatic transfo
rmation as they move between the different environments of an extracellular
insect stage and an intracellular form in the vertebrate host. In an attem
pt to develop new strategies for the treatment of leishmaniasis, the techni
ques of molecular genetics have been utilised to elucidate the mechanisms w
hich direct and control this cyclical differentiation. This review discusse
s current knowledge concerning the organization and regulation of the Leish
mania nuclear genome and includes a discussion of chromosomal organization,
genomic arrangement, transcription, transcript processing by trans-splicin
g and polyadenylation, and post-transcriptional regulation. The salient fea
tures as well as the supporting evidence for each topic are briefly reviewe
d.