A comparative study on the susceptibility of male and female albino mice to Trypanosoma brucei brucei.

BACKGROUND & OBJECTIVES: Trypanosomiasis has remained a major set-back in the development of livestock farming in tropical Africa. Thus the need for ascertaining the trypanotolerant levels of domestic animal breeds and possible improvement on them cannot be over-emphasised. METHODS: Level of trypanotolerance in animals was compared between sexes using albino mice infected with a Nigerian strain of Trypanosoma brucei brucei at a 50% mouse lethal dose (MLD50). RESULTS: The male mice showed unrestrained parasite growth with a prepatent period (PP) of two days and a mean survival period (MSP) of six days corresponding to a gradual decrease in packed cell volume (PCV), body weight, diet response and white blood cells (WBC) count to the time of death. Their female counterparts showed a PP of three days and MSP often days with a similar PCV gradient but a refractory WBC count. There was no significant difference in the differential leucocytes count in both sexes. However, the eosinophils count was significantly higher in the infected animals. It was found that female albino mice exercised more parasite restraint than their male counterparts. INTERPRETATION & CONCLUSION: The result suggests that the female animals may be more trypanotolerant hence may be more useful in protein production in trypanosomiasis endemic areas. However, further research using large domestic breeds like goats and sheep may be required to confirm the hypothesis.

Control of gene expression and genetic manipulation in the Trypanosomatidae

Mechanisms controlling gene expression in trypanosomatids depend on several layers of regulation, with most regulatory pathways acting at a post-transcriptional level. Consequently, these parasites can follow the rapid changes associated with transitions between the insect vector and the mammalian host, with instant reprogramming of genetic expression. Using primarily Trypanosoma brucei as a model, the basic controlling mechanisms have been elucidated and now researchers are beginning to define the cellular factors involved in the transcription, processing and translation of the mRNAs in these parasites. We describe some of the studies made on a subset of genes that are differentially expressed during the life cycles of T. brucei and T. cruzi. It is becoming evident that the regulatory strategies chosen by different species of trypanosomatids are not the same, and therefore, the lessons learned from one species do not necessarily apply to the others. Some of the tools available for genetic manipulation that have been developed along with these studies are also described. Two of them are of particular interest in this postgenomic period: inducible systems to express foreign genes and specific inhibition of gene expression by RNA interference