Cell-to-cell spread of microsporidia causesC. elegansorgans to form syncytia

Abstract

AbstractThe growth of pathogens is dictated by their interactions with the host environment. Many obligate intracellular pathogens undergo several cellular decisions as they progress through their life cycles inside of host cells. We studied this process for several species of microsporidia in the genusNematocidain their co-evolved animal hostCaenorhabditis elegans. We found that microsporidia can restructure multicellular host tissues into a single contiguous multinucleate cell. In particular, we found that all threeNematocidaspecies we studied were able to spread across the cells ofC. eleganstissues before forming spores, with two species causing syncytial formation in the intestine, and one species causing syncytial formation in the muscle. We also found that the decision to switch from replication to differentiation inN. parisiiwas altered by the density of infection, suggesting that environmental cues influence the dynamics of the pathogen life cycle. These findings show how microsporidia can maximize the use of host space for growth, and that environmental cues in the host can regulate a developmental switch in the pathogen.