Nematocida parisii

N. parisii is an intracellular parasite that is exclusively transmitted horizontally from one animal to another most commonly through the mouth or the feces.[3]Once N. parisii gets into the intestines it forms small ovoid microbes that cause the intestinal wall to be more textured. The small microbes then become spores and leave holes in the intestinal wall.[4]The microsporidian spores are likely to exit the cells by disrupting a conserved cytoskeletal structure in the intestine called the terminal web.[4] It seems that none of the known immune pathways of C. elegans is involved in mediating resistance against N. parisii. Microsporidia were found in several nematodes isolated from different locations, indicating that microsporidia are common natural parasites of C. elegans.

There are two life stages of N. parisii which include the spore stage and the meront stage.[5]The spores have a bulky cell wall to help them be able to live outside of the host cell during transmission.[5]The spores include a polar tube that aids in the infection of the host cell.[2]The tube helps the sporoplasm get into the host cell by turning itself inside out in order to get the sporoplasm close enough to the host cell to infect it.[2]The sporoplasm becomes the merit which then becomes more spores after infection within the host cell.[5]Once the spores have reached their mature stage they can can be let go for transmission to infect another host.[5]Since the genome size is small and there are very few metabolic pathways N. parisii needs its host to survive.[2]

The N. parisii–C. elegans system represents a very useful tool to study infection mechanisms of intracellular parasites.[4] Additionally, a new species of microsporidia was recently found in a wild caught C. elegans that genome sequencing places in the same genus Nematocida as prior microsporidia seen in these nematodes. This new species was named Nematocida displodere, after a phenotype seen in late infected worms that explode at the vulva to release infectious spores. N. displodere was shown to infect a broad range of tissues and cell types in C. elegans, including the epidermis, muscle, neurons, intestine, seam cells, and coelomocytes. Strangely, the majority of intestinal infection fails to grow to later parasite stages, while the muscle and epidermal infection thrives.[6] This is in stark contrast to N. parisii which infects and completes its entire life cycle in the C. elegans intestine. These related Nematocida species are being used to study the host and pathogen mechanisms responsible for allowing or blocking eukaryotic parasite growth in different tissue niches.

• Host–microbe interactions in Caenorhabditis elegans
• Intestinal parasite