Heritable genetic transformation of Strongyloides stercoralis by microinjection of plasmid DNA constructs into the male germline

Shao, Hongxia; Li, Xinshe; Lok, James B.

doi:10.1016/j.ijpara.2017.04.003

Cited by 19 publications

(17 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Sexual reproduction by S . stercoralis has also been confirmed recently by experimental crossing of free-living male and female worms harboring discrete reporter transgenes[ 65 ]. Although these findings do not exclude that asexual species or strains might exist, even within what is currently referred to as S .…”

Section: Discussionmentioning

confidence: 95%

Different but overlapping populations of Strongyloides stercoralis in dogs and humans—Dogs as a possible source for zoonotic strongyloidiasis

et al. 2017

Self Cite

View full text Add to dashboard Cite

Strongyloidiasis is a much-neglected soil born helminthiasis caused by the nematode Strongyloides stercoralis. Human derived S. stercoralis can be maintained in dogs in the laboratory and this parasite has been reported to also occur in dogs in the wild. Some authors have considered strongyloidiasis a zoonotic disease while others have argued that the two hosts carry host specialized populations of S. stercoralis and that dogs play a minor role, if any, as a reservoir for zoonotic S. stercoralis infections of humans. We isolated S. stercoralis from humans and their dogs in rural villages in northern Cambodia, a region with a high incidence of strongyloidiasis, and compared the worms derived from these two host species using nuclear and mitochondrial DNA sequence polymorphisms. We found that in dogs there exist two populations of S. stercoralis, which are clearly separated from each other genetically based on the nuclear 18S rDNA, the mitochondrial cox1 locus and whole genome sequence. One population, to which the majority of the worms belong, appears to be restricted to dogs. The other population is indistinguishable from the population of S. stercoralis isolated from humans. Consistent with earlier studies, we found multiple sequence variants of the hypervariable region I of the 18 S rDNA in S. stercoralis from humans. However, comparison of mitochondrial sequences and whole genome analysis suggest that these different 18S variants do not represent multiple genetically isolated subpopulations among the worms isolated from humans. We also investigated the mode of reproduction of the free-living generations of laboratory and wild isolates of S. stercoralis. Contrary to earlier literature on S. stercoralis but similar to other species of Strongyloides, we found clear evidence of sexual reproduction. Overall, our results show that dogs carry two populations, possibly different species of Strongyloides. One population appears to be dog specific but the other one is shared with humans. This argues for the strong potential of dogs as reservoirs for zoonotic transmission of S. stercoralis to humans and suggests that in order to reduce the exposure of humans to infective S. stercoralis larvae, dogs should be treated for the infection along with their owners.

show abstract

Section: Discussionmentioning

confidence: 95%

Different but overlapping populations of Strongyloides stercoralis in dogs and humans—Dogs as a possible source for zoonotic strongyloidiasis

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…Further adding to the potential utility of S . stercoralis , a recent study demonstrated that heritable transgenesis is also possible by microinjection of plasmid constructs into the testicular syncytium of free-living males [ 41 ]. Future CRISPR-Cas9 strategies simultaneously targeting both S .…”

Section: Discussionmentioning

confidence: 99%

Targeted mutagenesis in a human-parasitic nematode

et al. 2017

View full text Add to dashboard Cite

Parasitic nematodes infect over 1 billion people worldwide and cause some of the most common neglected tropical diseases. Despite their prevalence, our understanding of the biology of parasitic nematodes has been limited by the lack of tools for genetic intervention. In particular, it has not yet been possible to generate targeted gene disruptions and mutant phenotypes in any parasitic nematode. Here, we report the development of a method for introducing CRISPR-Cas9-mediated gene disruptions in the human-parasitic threadworm Strongyloides stercoralis. We disrupted the S. stercoralis twitchin gene unc-22, resulting in nematodes with severe motility defects. Ss-unc-22 mutations were resolved by homology-directed repair when a repair template was provided. Omission of a repair template resulted in deletions at the target locus. Ss-unc-22 mutations were heritable; we passed Ss-unc-22 mutants through a host and successfully recovered mutant progeny. Using a similar approach, we also disrupted the unc-22 gene of the rat-parasitic nematode Strongyloides ratti. Our results demonstrate the applicability of CRISPR-Cas9 to parasitic nematodes, and thereby enable future studies of gene function in these medically relevant but previously genetically intractable parasites.

show abstract

“…Intragonadal microinjection has also been used to generate transgenics in the closely related nematode Parastrongyloides trichosuri, a parasite of Australian brushtail possums that can cycle through multiple free-living generations (Grant et al, 2006). Strongyloides stercoralis free-living adult males are also amenable to genetic transformation via microinjection into the syncytial testes (Shao et al, 2017). The ability to cycle through one or more free-living generations is specific to the genera Strongyloides and Parastrongyloides (Lok, 2007).…”

Section: Transgenesis In Strongyloides Speciesmentioning

confidence: 99%

Recent advances in functional genomics for parasitic nematodes of mammals

Castelletto

Gang

Hallem

2020

Journal of Experimental Biology

View full text Add to dashboard Cite

Human-parasitic nematodes infect over a quarter of the world's population and are a major cause of morbidity in low-resource settings. Currently available treatments have not been sufficient to eliminate infections in endemic areas, and drug resistance is an increasing concern, making new treatment options a priority. The development of new treatments requires an improved understanding of the basic biology of these nematodes. Specifically, a better understanding of parasitic nematode development, reproduction and behavior may yield novel drug targets or new opportunities for intervention such as repellents or traps. Until recently, our ability to study parasitic nematode biology was limited because few tools were available for their genetic manipulation. This is now changing as a result of recent advances in the large-scale sequencing of nematode genomes and the development of new techniques for their genetic manipulation. Notably, skin-penetrating gastrointestinal nematodes in the genus Strongyloides are now amenable to transgenesis, RNAi and CRISPR/Cas9-mediated targeted mutagenesis, positioning the Strongyloides species as model parasitic nematode systems. A number of other mammalian-parasitic nematodes, including the giant roundworm Ascaris suum and the tissue-dwelling filarial nematode Brugia malayi, are also now amenable to transgenesis and/or RNAi in some contexts. Using these tools, recent studies of Strongyloides species have already provided insight into the molecular pathways that control the developmental decision to form infective larvae and that drive the host-seeking behaviors of infective larvae. Ultimately, a mechanistic understanding of these processes could lead to the development of new avenues for nematode control.

show abstract

Heritable genetic transformation of Strongyloides stercoralis by microinjection of plasmid DNA constructs into the male germline

Cited by 19 publications

References 25 publications

Different but overlapping populations of Strongyloides stercoralis in dogs and humans—Dogs as a possible source for zoonotic strongyloidiasis

Different but overlapping populations of Strongyloides stercoralis in dogs and humans—Dogs as a possible source for zoonotic strongyloidiasis

Targeted mutagenesis in a human-parasitic nematode

Recent advances in functional genomics for parasitic nematodes of mammals

Contact Info

Product

Resources

About