Differentiation patterns of Trypanosoma Brucei field isolates

Abstract

The developmental biology of differentiation is a universal biological process that allows cells to adapt to different environments and to perform specific functions. In the life cycle of T. brucei, this process is tightly regulated in preparation of the parasite for life in another host, characterized by events that comprise integrated changes in cell morphology, signaling pathways, metabolism, and gene expression. To date, most research done to elucidate these events has mostly been on laboratory-adapted isolates (those that have been serially passaged in animal models or in-vitro laboratory culture) with little done to replicate the same findings in field isolates. (Field isolates being those that have been obtained from natural animal infections). This study describes the growth and differentiation characteristics of 3 T. b. brucei isolates and 1 T.b.rhodesiense isolate from cattle and human patients respectively. The analysis of the growth characteristics and differentiation patterns of four T. brucei field isolates was based on parasitemia, cell cycle stages, duration of stumpy formation in-vivo, morphological change, and time points of cell surface antigen change using in-vivo (swiss Albino mice and Wister rats [male]) and in-vitro (HM19 [bloodstream form] & SDM79 [procyclic form] culture media) methods. The analysis revealed within the same sub-species of the T.brucei field isolate strains, there were variations in the rate of proliferation. In addition, there were different populations of cells within the G2/M phase of the cell cycle in mice. Further, the different field isolates showed varying virulence in mice fluctuating from sub-acute to chronic parasitemia. In contrast, differentiation patterns in-vitro of the isolates showed expression of the procyclin surface protein EP by the 12th-hour point post-induction of cell differentiation. However, the rate of differentiation varied between isolates. This study revealed varying phenotypic growth characteristics and differentiation patterns in T. brucei field isolates. The molecular mechanisms underlying this observation need to be elucidated.