Microsporidia Infections In Caenorhabditis Elegans And Related Nematodes

Microsporidia are fungi-related intracellular pathogens that infect a great variety of animals,including the nematode Caenorhabditis elegans.The first microsporidia isolated from wild C.elegans was named Nematocida parisii in 2008.C.elegans and N.parisii have been used as a powerful model for the study of host-pathogen interactions.However,it was unclear how widespread and diverse microsporidia infections are in C.elegans or other related nematodes in the wild.By sampling rhabditid nematodes worldwide,we established a collection of 47 nematodes that displayed putative microsporidia infections.We characterized molecularly these infections and determined that N.parisii(or N.ironsii)is the most common microsporidia infecting C.elegans in the wild.We further described and named six new Nematocida species.In addition,we defined two new genera of nematode-infecting microsporidia,named Enteropsectra and Pancytospora,which are genetically distinct from Nematocida.Further investigations showed that these microsporidia are diverse in terms of spore size and shape,host tissue tropism,host cell intracellular localization,cellular exit route,host specificity pattern,etc.Overall,these findings illustrate the widespread and diverse microsporidia infections in C.elegans and related nematodes in the wild.We further assayed the natural variation of C.elegans in sensitivity to N.ausubeli infection,by comparing 10 C.elegans strains using food consumption tests.Two C.elegans strains,JU1249 and JU2825,displayed the largest sensitivity differences,which were suggested to be a result of the different tolerance between the two strains.These two strains are proven to be good candidates for future studies on the genetic loci associated with C.elegans sensitivity variation to microsporidian infections.Furthermore,I observed an exciting effect of host-pathogen interaction.Microsporidia infection is able to suppress the progressive decline in fertility in some C.elegans with the mortal germline phenotype(Mrt).