The application of gene expression microarray technology to kinetoplastid research.

Protozoan parasites in the order Kinetoplastida cause severe disease primarily in tropical and subtropical areas. Vaccines to control these diseases have shown some promise, but none are in active clinical use. Drug treatments are available for all of the acute infections, but the emergence of resistance and an unresponsive chronic phase are current problems. Rapid advances in genomic technology open the possibility of discovering new genes that can contribute to vaccine initiatives or serve as targets for development of new drugs. The DNA microarray is a genomic technology, which is being applied to new gene discovery in kinetoplastid parasites. Both cDNA and genomic microarrays for Leishmania major have identified a number of new genes that are expressed in a stage-specific fashion and preliminary results from a L. donovani genomic microarray also demonstrated new gene discovery. A microarray of Trypanosoma brucei genomic fragments identified new genes whose expression differs between the insect borne stage and the human infectious stage of the parasite. The next few years, building on this foundational work, should witness the most exciting stage as microarrays are applied to questions such as the basis of drug resistance, post kala azar dermal leishmaniasis, the regulation of differentiation to infectious stages, linking coordinately regulated pathways of genes and development of genetically defined parasites that may have potential as live attenuated vaccines.