Evolving Differentiation in African Trypanosomes

Differentiation is a central aspect of the parasite life cycle and encompasses adaptation to both host and environment. If we accept that evolution cannot anticipate an organism's needs as it enters a new environment, how do parasite differentiation pathways arise? The transition between vertebrate and insect stage African trypanosomes is probably one of the better studied and involves a cell-cycle arrested or 'stumpy' form that activates metabolic pathways advantageous to the parasite in the insect host. However, a range of stimuli and stress conditions can trigger similar changes, leading to formation of stumpy-like cellular states. We propose that the origin and optimisation of this differentiation program represents repurposing of a generic stress response to gain considerable gain-of-fitness associated with parasite transmission.

Automated summary

Parasite differentiation is essential for adaptation to hosts and environments, with the transition between vertebrate and insect stages being well studied in African trypanosomes. Activation of advantageous metabolic pathways in the insect host leads to the formation of a 'stumpy' form. Various stimuli and stress conditions can trigger similar changes, suggesting a repurposing of a generic stress response for gains in parasite fitness during transmission.