A sticky situation: When trypanosomatids attach to insect tissues

Abstract

Transmission of trypanosomatids to their mammalian hosts requires a complex series of developmental transitions in their insect vectors, including stable attachment to an insect tissue. While there are many ultrastructural descriptions of attached cells, we know little about the signaling events and molecular mechanisms involved in this process. Each trypanosomatid species attaches to a specific tissue in the insect at a particular stage of its life cycle. Attachment is mediated by the flagellum, which is modified to accommodate a filament-rich plaque within an expanded region of the flagellar membrane. Attachment immediately precedes differentiation to the mammal-infectious stage and in some cases a direct mechanistic link has been demonstrated. In this review, we summarize the current state of knowledge of trypanosomatid attachment in insects, including structure, function, signaling, candidate molecules, and changes in gene expression. We also highlight remaining questions about this process and how the field is poised to address them through modern approaches.

Genetic modification of the bee parasiteCrithidia bombifor improved visualization and protein localization

“…Once in the host, parasites often accumulate in the hindgut and rectum, adhering to the lining of these tissues by their single flagellum and dividing by binary fission as attached cells [4]. The structure of this flagellar attachment is similar in all trypanosomatids [5,6].…”

“…Discovering the effects of floral products on these activities could improve our understanding of how these different aspects of parasite biology contribute to productive infections. Although all trypanosomatids, including human pathogens, attach to tissues in their insect hosts [6], insect parasites do so in great numbers [4], meaning they could serve as a model for insect colonization by trypanosomatids more generally. In addition, improved understanding of the effects of pollen and nectar diets on the mechanisms underlying parasite infections could allow us to predict the impacts of floral resources on pathogen load and pollinator health.…”