Discovery of a Natural Microsporidian Pathogen with a Broad Tissue Tropism in Caenorhabditis elegans
(a) Infected head region of a live C. elegans animal from strain JU2807 (derived from the wild-isolated P0 animal, see S1 Fig) showing a large group of structures that appear to be meronts (Me) adjacent to the pharynx (Ph) and intestine (In). (b) Infected head region with the area adjacent to the pharynx filled with spores (Sp). (c) The mid-posterior to tail region of N2 C. elegans infected with N. displodere from 1 dpi to 7 dpi at 15°C visualized by FISH to stain parasite rRNA (red), DAPI to stain nuclei (blue), and DY96 to stain the chitin of parasite spore walls (green). Animals were at the L2 larval stage at 1 dpi, L3 stage at 2 dpi, L4 stage at 3 dpi, and adult stage at 4–7 dpi. Sporoplasms (Sppl), meronts (Me), sporonts (Spnt), and spores (Sp) are indicated. Scale bars are 10 μm. (d) Quantification of symptoms of N. displodere infection over time at 15°C with N2 animals infected as starved L1 larvae at T0. Sporoplasms are mononucleated structures, meronts are multinucleated structures, and sporoblasts are rounded, mononucleated structures stained by FISH (see c above). Spores are oblong DY96-stained structures in infected animals. Fifty animals were quantified for each replicate at each time point, and data points indicate the mean and standard deviation (SD) from four replicates across two experiments. Each symptom was fit to a Boltzmann sigmoidal curve (R square > 0.99 for each curve), and the time to 50% of the animals exhibiting symptoms (T50) is shown.