The ins and outs of host‐microsporidia interactions during invasion, proliferation and exit

Abstract

Microsporidia are a large group of fungal-related obligate intracellular parasites. They are responsible for infections in humans as well as in agriculturally and environmentally important animals. Although microsporidia are abundant in nature, many of the molecular mechanisms employed during infection have remained enigmatic. In this review, we highlight recent work showing how microsporidia invade, proliferate and exit from host cells. During invasion, microsporidia use spore wall and polar tube proteins to interact with host receptors and adhere to the host cell surface. In turn, the host has multiple defence mechanisms to prevent and eliminate these infections. Microsporidia encode numerous transporters and steal host nutrients to facilitate proliferation within host cells. They also encode many secreted proteins which may modulate host metabolism and inhibit host cell defence mechanisms. Spores exit the host in a non-lytic manner that is dependent on host actin and endocytic recycling proteins. Together, this work provides a fuller picture of the mechanisms that these fascinating organisms use to infect their hosts.

High-throughput small molecule screen identifies inhibitors of microsporidia invasion and proliferation in C. elegans

“…Once microsporidia spores are exposed to a host signal, the osmotic pressure of the spore increases forcing the polar tube to be extruded. One protein hypothesized to control spore firing is the subtilisin serine protease which is conserved throughout microsporidia (58). This protein localizes to the poles of N. bombycis spores, and the activated version of the protease localizes to the end of the spore from which the polar tube fires (59).…”

Two parasites in one host: spatiotemporal dynamics and co-occurrence of Microsporidia and Rickettsia in an amphipod host

“…For example, even if both microsporidians and Rickettsia infect the same individual, the exact host organs and tissues they target (i.e. tissue tropism) and how they interact with the host cell may be different (Sahni and Rydkina, 2009;Tamim El Jarkass and Reinke, 2020). If one is transmitted horizontally and the other is transmitted vertically, they are likely to be located in different tissues and organs and might not need to compete for the same resources.…”

Editorial: Recent Advances in the Controversial Human Pathogens Pneumocystis, Microsporidia and Blastocystis

“…It is the developmental stage used in transmission of microsporidia and invasion of host cells. Once the spores are ingested, the polar tube inside ejects, delivering the sporoplasm into host cells (Tamim El Jarkass and Reinke, 2020 ). The invasion mechanism of microsporidia remains poorly explored.…”