Strongyloides stercoralis and Relatives: Recent Advances in General and Molecular Biology

Abstract

Human strongyloidiasis is a threat to global health, presenting significant challenges in diagnosis and clinical management. The imperative to incorporate strongyloidiasis more fully into control programs for soil-transmitted helminths is increasingly recognized. The unique life cycles of Strongyloides stercoralis and congeneric species contain both free-living and parasitic generations, and transcriptomic methods have recently identified genes of potential importance to parasitism in these worms. Proteomics recently revealed stage-specific secreted proteins that appear crucial to the host-parasite interaction. A comprehensive genome sequencing project for Strongyloides spp. is now nearing completion. Recent technical advances in transgenesis for S. stercoralis and S. ratti, including the first establishment of stable transgenic lines, promise to advance functional evaluations of genes expressed in conjunction with crucial life-cycle events. Studies employing these methods recently bolstered the hypothesis that S. stercoralis uses cellular signaling pathways homologous to three that regulate dauer larval development in Caenorhabditis elegans to regulate morphogenesis and development of its infective third-stage larva. The freeliving generation of Strongyloides makes classical genetics formally possible. Recent advances, such as a genetic map of S. ratti and a molecular genetic and karyotypic analysis of sex determination in S. papillosus, will greatly facilitate this approach. Advanced methods for study of chemosensation in C. elegans were recently applied to discover numerous hostattractant molecules that mediate host finding and contact by infective third-stage larvae of Strongyloides spp. Finally, nucleic acid-based diagnostic methods have recently come to the fore as alternatives to parasitological and immunodiagnostic techniques.

Strongyloides stercoralis in Alcoholic Patients: Implications of Alcohol Intake in the Frequency of Infection and Parasite Load

“…This leads to a reinfection by the larvae invasion of the intestinal wall [ 5 ] and is called autoinfection. When it occurs in low, well-regulated levels, it leads to chronic infection in immunocompetent individuals [ 6 ]. However, in immunocompromised patients, the autoinfection cycle can be intensified, leading to hyperinfection and/or dissemination of strongyloidiasis, which can potentially be life-threatening and has a mortality rate of up to 87% [ 7 , 8 ].…”

Strongyloides stercoralis: current perspectives

“…93 Because of the extra X chromosome, females are capable of reproducing parthenogenetically to both female and male offspring. It is estimated that the genome of S. stercoralis codes for 13,114 genes, which have significantly fewer and smaller introns compared to Caenorhabditis elegans and parasitic nematodes representing Clades I, III, and V. 94,95 With the advent of DNA sequencing technology, the initial focus of genomic analysis was sequencing of expressed sequence tags (ESTs), or short DNA sequences of gene-coding regions reverse-transcribed from mRNA, to identify diagnostic and vaccine candidate genes. Ramachandran …”

Advances in the Molecular and Cellular Biology of Strongyloides spp.

“…A previous review in Current Tropical Medicine Reports [28] covered contemporary advances in the cellular and molecular biology of Strongyloides spp. up to 2014.…”