International Journal for Parasitology: Drugs and Drug Resistance最新文献

{"title":"The Haemonchus contortus LGC-39 subunit is a novel subtype of an acetylcholine-gated chloride channel","authors":"Sarah Habibi ,&nbsp;Kristen Nazareth ,&nbsp;Jennifer Nichols,&nbsp;Sierra Varley,&nbsp;Sean G. Forrester","doi":"10.1016/j.ijpddr.2023.04.001","DOIUrl":"10.1016/j.ijpddr.2023.04.001","url":null,"abstract":"<div><p>The nematode genome exhibits a vast array of Cys-loop receptors that are activated by a diverse set of neurotransmitters and anthelmintic drugs such as ivermectin and levamisole. While many Cys-loop receptors have been functionally and pharmacologically characterized, there remains a large subset of orphan receptors where the agonist remains unknown. We have identified an orphan Cys-loop receptor, LGC-39, from the parasitic nematode <em>Haemonchus contortus</em> that is a novel type of cholinergic-sensitive ligand-gated chloride channel. This receptor groups outside of the acetylcholine-gated chloride channel family, in the previously named GGR-1 (GABA/Glycine Receptor-1) group of Cys-loop receptors. We found that LGC-39 forms a functional homomeric receptor when expressed in <em>Xenopus laevis</em> oocytes and is activated by several cholinergic ligands including acetylcholine, methacholine and surprisingly, atropine with an EC₅₀ for atropine on the low μM range. A homology model was generated which revealed some key features of the LGC-39 ligand-binding pocket that may explain some of the elements important for atropine recognition of the LGC-39 receptor. Overall these results suggest that the GGR-1 family (now called LGC-57) of Cys-loop receptors includes novel acetylcholine-gated chloride channel subtypes and may represent important future drug targets.</p></div>","PeriodicalId":13775,"journal":{"name":"International Journal for Parasitology: Drugs and Drug Resistance","volume":"22 ","pages":"Pages 20-26"},"PeriodicalIF":4.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10122009/pdf/main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10267427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transcriptomic analysis of albendazole resistance in human diarrheal parasite Giardia duodenalis","authors":"Qiao Su ,&nbsp;Louise Baker ,&nbsp;Samantha Emery ,&nbsp;Balu Balan ,&nbsp;Brendan Ansell ,&nbsp;Swapnil Tichkule ,&nbsp;Ivo Mueller ,&nbsp;Staffan G. Svärd ,&nbsp;Aaron Jex","doi":"10.1016/j.ijpddr.2023.03.004","DOIUrl":"10.1016/j.ijpddr.2023.03.004","url":null,"abstract":"<div><p>Benzimidazole-2-carbamates (BZ, e.g., albendazole; ALB), which bind β-tubulin to disrupt microtubule polymerization, are one of two primary compound classes used to treat giardiasis. In most parasitic nematodes and fungi, BZ-resistance is caused by β-tubulin mutations and its molecular mode of action (MOA) is well studied. In contrast, in <em>Giardia duodenalis</em> BZ MOA or resistance is less well understood, may involve target-specific and broader impacts including cellular damage and oxidative stress, and its underlying cause is not clearly determined. Previously, we identified acquisition of a single nucleotide polymorphism, E198K, in β-tubulin in ALB-resistant (ALB-R) <em>G. duodenalis</em> WB-1B relative to ALB-sensitive (ALB-S) parental controls. E198K is linked to BZ-resistance in fungi and its allelic frequency correlated with the magnitude of BZ-resistance in <em>G. duodenalis</em> WB-1B. Here, we undertook detailed transcriptomic comparisons of these ALB-S and ALB-R <em>G. duodenalis</em> WB-1B cultures. The primary transcriptional changes with ALB-R in <em>G. duodenalis</em> WB-1B indicated increased protein degradation and turnover, and up-regulation of tubulin, and related genes, associated with the adhesive disc and basal bodies. These findings are consistent with previous observations noting focused disintegration of the disc and associated structures in <em>Giardia duodenalis</em> upon ALB exposure. We also saw transcriptional changes with ALB-R in <em>G. duodenalis</em> WB-1B consistent with prior observations of a shift from glycolysis to arginine metabolism for ATP production and possible changes to aspects of the vesicular trafficking system that require further investigation. Finally, we saw mixed transcriptional changes associated with DNA repair and oxidative stress responses in the <em>G. duodenalis</em> WB-1B line. These changes may be indicative of a role for H₂O₂ degradation in ALB-R, as has been observed in other <em>G. duodenalis</em> cell cultures. However, they were below the transcriptional fold-change threshold (log₂FC &gt; 1) typically employed in transcriptomic analyses and appear to be contradicted in ALB-R <em>G. duodenalis</em> WB-1B by down-regulation of the NAD scavenging and conversion pathways required to support these stress pathways and up-regulation of many highly oxidation sensitive iron-sulphur (FeS) cluster based metabolic enzymes.</p></div>","PeriodicalId":13775,"journal":{"name":"International Journal for Parasitology: Drugs and Drug Resistance","volume":"22 ","pages":"Pages 9-19"},"PeriodicalIF":4.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10111952/pdf/main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9893540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification and characterization of novel marine oxasqualenoid yucatecone against Naegleria fowleri","authors":"Iñigo Arberas-Jiménez ,&nbsp;Francisco Cen-Pacheco ,&nbsp;Javier Chao-Pellicer ,&nbsp;Ines Sifaoui ,&nbsp;Aitor Rizo-Liendo ,&nbsp;Ezequiel Q. Morales ,&nbsp;Antonio H. Daranas ,&nbsp;Ana R. Díaz-Marrero ,&nbsp;José E. Piñero ,&nbsp;José J. Fernández ,&nbsp;Jacob Lorenzo-Morales","doi":"10.1016/j.ijpddr.2023.05.004","DOIUrl":"10.1016/j.ijpddr.2023.05.004","url":null,"abstract":"<div><p><em>Naegleria fowleri</em> is an opportunistic protozoan, belonging to the free-living amoeba group, that can be found in warm water bodies. It is causative agent the primary amoebic meningoencephalitis, a fulminant disease with a rapid progression that affects the central nervous system. However, no 100% effective treatments are available and those that are currently used involve the appearance of severe side effects, therefore, there is an urgent need to find novel antiamoebic compounds with low toxicity. In this study, the <em>in vitro</em> activity of six oxasqualenoids obtained from the red algae <em>Laurencia viridis</em> was evaluated against two different strains of <em>N</em>. <em>fowleri</em> (ATCC® 30808 and ATCC® 30215) as well as their cytotoxicity against murine macrophages. Yucatecone was the molecule with the highest selectivity index (&gt;2.98 and 5.23 respectively) and it was selected to continue with the cell death type determination assays. Results showed that yucatone induced programmed cell death like responses in treated amoebae causing DNA condensation and cellular membrane damage among others. In this family of oxasqualenoids, it seems that the most significative structural feature to induce activity against <em>N</em>. <em>fowleri</em> is the presence of a ketone at C-18. This punctual oxidation transforms an inactive compound into a lead compound as the yucatecone and 18-ketodehydrotyrsiferol with IC₅₀ values of 16.25 and 12.70 μM, respectively. The assessment of <em>in silico</em> ADME/Tox analysis revealed that the active compounds showed good Human Oral Absorption and demonstrate that are found to be within the limit of approved drug parameter range. Hence, the study highlights promising potential of yucatone to be tested for therapeutic use against primary amoebic meningoencephalitis.</p></div>","PeriodicalId":13775,"journal":{"name":"International Journal for Parasitology: Drugs and Drug Resistance","volume":"22 ","pages":"Pages 61-71"},"PeriodicalIF":4.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10258243/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9894089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integration of ITS-2 rDNA nemabiome metabarcoding with Fecal Egg Count Reduction Testing (FECRT) reveals ivermectin resistance in multiple gastrointestinal nematode species, including hypobiotic Ostertagia ostertagi, in western Canadian beef cattle","authors":"Eranga L. De Seram ,&nbsp;Fabienne D. Uehlinger ,&nbsp;Camila de Queiroz ,&nbsp;Elizabeth M. Redman ,&nbsp;John R. Campbell ,&nbsp;Drue Nooyen ,&nbsp;Arianna Morisetti ,&nbsp;Colleen M. Pollock ,&nbsp;Samantha Ekanayake ,&nbsp;Gregory B. Penner ,&nbsp;John S. Gilleard","doi":"10.1016/j.ijpddr.2023.04.002","DOIUrl":"10.1016/j.ijpddr.2023.04.002","url":null,"abstract":"<div><p>A large-scale Fecal Egg Count Reduction Test (FECRT) was integrated with ITS-2 rDNA nemabiome metabarcoding to investigate anthelmintic resistance in gastrointestinal nematode (GIN) parasites in western Canadian beef cattle. The study was designed to detect anthelmintic resistance with the low fecal egg counts that typically occur in cattle in northern temperate regions. Two hundred and thirty-four auction market-derived, fall-weaned steer calves coming off pasture were randomized into three groups in feedlot pens: an untreated control group, an injectable ivermectin treatment group, and an injectable ivermectin/oral fenbendazole combination treatment group. Each group was divided into six replicate pens with 13 calves per pen. Individual fecal samples were taken pre-treatment, day 14 post-treatment, and at monthly intervals for six months for strongyle egg counting and metabarcoding. Ivermectin treatment resulted in an 82.4% mean strongyle-type fecal egg count reduction (95% CI 67.8–90.4) at 14 days post-treatment, while the combination treatment was 100% effective, confirming the existence of ivermectin-resistant GIN. Nemabiome metabarcoding of third-stage larvae from coprocultures revealed an increase in the relative abundance of <em>Cooperia oncophora, Cooperia punctata,</em> and <em>Haemonchus placei</em> at 14 days post-ivermectin treatment indicating ivermectin resistance in adult worms. In contrast, <em>Ostertagia ostertagi</em> third-stage larvae were almost completely absent from day 14 coprocultures, indicating that adult worms of this species were not ivermectin resistant. However, there was a recrudescence of <em>O. ostertagi</em> third stage larvae in coprocultures at three to six months post-ivermectin treatment, which indicated ivermectin resistance in hypobiotic larvae. The calves were recruited from the auction market and, therefore, derived from multiple sources in western Canada, suggesting that ivermectin-resistant parasites, including hypobiotic <em>O. ostertagi</em> larvae, are likely widespread in western Canadian beef herds. This work demonstrates the value of integrating ITS-2 rDNA metabarcoding with the FECRT to enhance anthelmintic resistance detection and provide GIN species- and stage-specific information.</p></div>","PeriodicalId":13775,"journal":{"name":"International Journal for Parasitology: Drugs and Drug Resistance","volume":"22 ","pages":"Pages 27-35"},"PeriodicalIF":4.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/ae/97/main.PMC10165142.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9903190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Forward genetic analysis of monensin and diclazuril resistance in Eimeria tenella","authors":"Hongtao Zhang ,&nbsp;Lei Zhang ,&nbsp;Ganglin Ren ,&nbsp;Hongbin Si ,&nbsp;Xingju Song ,&nbsp;Xianyong Liu ,&nbsp;Xun Suo ,&nbsp;Dandan Hu","doi":"10.1016/j.ijpddr.2023.05.002","DOIUrl":"10.1016/j.ijpddr.2023.05.002","url":null,"abstract":"<div><p>Worldwide distributed coccidiosis is caused by infection of both <em>Eimeria</em> species and <em>Cystoisospora</em> in the host intestine and causes huge economic losses to the livestock industry, especially the poultry industry. The control of such diseases relies mainly on chemoprophylaxis with anticoccidials, which has led to a very common drug resistance in this field. However, the genetic mechanisms underlying resistance to many anticoccidial drugs remain unknown. In this study, strains of <em>E. tenella</em> resistant to 250 mg/kg monensin were generated and characterized. Forward genetic approaches based on pooled genome sequencing, including experimental evolution and linkage group selection, were used to locate candidate targets responsible for resistance to monensin and diclazuril in <em>E. tenella</em>. A total of 16 nonsynonymous mutants in protein-coding genes were identified in monensin-resistant strains, and two genomic regions with strong selection signals were also detected in diclazuril-resistant strains. Our study reveals the genetic characterization of the experimental evolution and linkage group selection in <em>Eimeria</em> species, and also provides important information that contributes to the understanding of the molecular mechanism of drug resistance in coccidia.</p></div>","PeriodicalId":13775,"journal":{"name":"International Journal for Parasitology: Drugs and Drug Resistance","volume":"22 ","pages":"Pages 44-51"},"PeriodicalIF":4.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238932/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10267949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In vitro activity and mechanism of cell death induction of cyanomethyl vinyl ethers derivatives against Trypanosoma cruzi","authors":"Carlos J. Bethencourt-Estrella ,&nbsp;Samuel Delgado-Hernández ,&nbsp;Atteneri López-Arencibia ,&nbsp;Desirée San Nicolás-Hernández ,&nbsp;David Tejedor ,&nbsp;Fernando García-Tellado ,&nbsp;Jacob Lorenzo-Morales ,&nbsp;José E. Piñero","doi":"10.1016/j.ijpddr.2023.05.001","DOIUrl":"10.1016/j.ijpddr.2023.05.001","url":null,"abstract":"<div><p>Chagas disease causes a problematic pathology that can lead to megacolon and heart disease, and can even cause the death of the patient. Current therapies for this disease are the same as they were 50 years ago, are not fully effective and have strong side effects. The lack of a safe and effective therapy makes it necessary to search for new, less toxic and totally effective compounds against this parasite. In this work, the antichagasic activity of 46 novel cyanomethyl vinyl ether derivatives was studied. In addition, to elucidate the type of cell death that these compounds produce in parasites, several events related to programmed cell death were studied. The results highlight four more selective compounds, E63, E64, E74 and E83, which also appear to trigger programmed cell death, and are therefore postulated as good candidates to use in future therapeutics for Chagas disease.</p></div>","PeriodicalId":13775,"journal":{"name":"International Journal for Parasitology: Drugs and Drug Resistance","volume":"22 ","pages":"Pages 72-80"},"PeriodicalIF":4.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/79/e1/main.PMC10276036.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10268451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a three-colour digital PCR for early and quantitative detection of benzimidazole resistance-associated single nucleotide polymorphisms in Haemonchus contortus","authors":"Barbara Hinney ,&nbsp;Sandra Wiedermann ,&nbsp;Antonio Bosco ,&nbsp;Laura Rinaldi ,&nbsp;Martin Hofer ,&nbsp;Anja Joachim ,&nbsp;Jürgen Krücken ,&nbsp;Ralf Steinborn","doi":"10.1016/j.ijpddr.2023.06.001","DOIUrl":"10.1016/j.ijpddr.2023.06.001","url":null,"abstract":"<div><p><em>Haemonchus contortus</em> is the most pathogenic nematode in small ruminants and anthelmintic resistance (AR) hampers its efficient control. Early detection of AR status is required to reduce selection for AR and cannot be achieved using phenotypic tests. For benzimidazoles (BZs), the detection of AR-associated alleles characterised by single nucleotide polymorphisms (SNPs) in the isotype 1 β-tubulin gene allows early AR detection in strongyles. The F200Y, F167Y, E198A and E198L polymorphisms have been described in BZ-resistant populations with a clear variation in frequencies between regions. A novel digital PCR (dPCR) enables the detection of all of the above-described polymorphisms in <em>H. contortus</em>. Assays were validated using synthetic DNA fragments containing these SNPs. Then, larvae obtained and pooled at farm level from 26 Austrian and 10 Italian sheep farms were analysed. For all assays a detection limit of 15 copies/μl of resistance alleles and a high level of accuracy were demonstrated, allowing to detect allele frequencies of 1% in most samples. In Austrian samples, elevated frequencies of F200Y resistance alleles were detected on all farms. Polymorphisms in codon 167 and codon 198 were identified in <em>H. contortus</em> from Austria for the first time. In Italian samples, the frequency of resistance alleles was still comparatively low, but F200Y resistance alleles were traceable. In conclusion we developed for the first time dPCR assays that target all SNPs of relevance associated with BZ-resistance in <em>H. contortus</em>. Future research on AR development could benefit from an early onset of SNP-based surveillance that would include the developed assays for all SNPs of relevance. Improved surveillance in the long term will include other important, though less pathogenic, nematode genera in the analyses.</p></div>","PeriodicalId":13775,"journal":{"name":"International Journal for Parasitology: Drugs and Drug Resistance","volume":"22 ","pages":"Pages 88-95"},"PeriodicalIF":4.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/86/a7/main.PMC10336075.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10268475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reflecting on the past and fast forwarding to present day anthelmintic resistant Ancylostoma caninum–A critical issue we neglected to forecast","authors":"Antoinette E. Marsh ,&nbsp;Jeffrey Lakritz","doi":"10.1016/j.ijpddr.2023.04.003","DOIUrl":"10.1016/j.ijpddr.2023.04.003","url":null,"abstract":"<div><p>Reports of anthelmintic resistance in <em>Ancylostoma caninum</em> are increasing in frequency in the United States of America (USA). In the last few years <em>in vitro</em> and <em>in vivo</em> studies characterized individual isolates, demonstrating multiple anthelmintic drug resistance (MADR). In 2021, the American Association of Veterinary Parasitologists initiated a hookworm task force to address this issue. The first report of drug resistant <em>A. caninum</em> occurred in 1987 in Australian racing Greyhounds. In the last five years multiple case reports and investigations show drug resistant <em>A. caninum</em> is becoming a much greater problem in the USA and now extends beyond racing Greyhounds into the general companion animal dog population. The literature, regarding drug resistance in livestock and equine nematodes, provides helpful guidance along with diagnostic methods to better understand the evolution and selection of canine MADR hookworms; however, there are limitations and caveats due to <em>A. caninum's</em> unique biology and zoonotic potential. Mass drug administration (MDA) of anthelminthic drugs to humans to reduce morbidity associated with human hookworms (<em>Necator americanus</em>) should consider the factors that contributed to the development of MADR <em>A. caninum</em>. Finally, as Greyhound racing undergoes termination in some regions and the retired dogs undergo subsequent rehoming, drug resistant parasites, if present, are carried with them. Drug resistant <em>A. caninum</em> requires greater recognition by the veterinary community, and small animal practitioners need to be aware of the spread into current pet dog populations. The current understanding of anthelmintic resistance, available treatments, and environmental mitigation for these drug resistant <em>A. caninum</em> isolates must be monitored for horizontal spread. A major goal in this emerging problem is to prevent continued dissemination.</p></div>","PeriodicalId":13775,"journal":{"name":"International Journal for Parasitology: Drugs and Drug Resistance","volume":"22 ","pages":"Pages 36-43"},"PeriodicalIF":4.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/12/46/main.PMC10229760.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9946081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ascaridia galli - An old problem that requires new solutions","authors":"Johan Höglund ,&nbsp;Gürbüz Daş ,&nbsp;Behdad Tarbiat ,&nbsp;Peter Geldhof ,&nbsp;Désirée S. Jansson ,&nbsp;Matthias Gauly","doi":"10.1016/j.ijpddr.2023.07.003","DOIUrl":"10.1016/j.ijpddr.2023.07.003","url":null,"abstract":"<div><p>Reports of <em>Ascaridia galli</em> in laying hens in Europe have increased since the ban on conventional battery cages in 2012. As this parasite is transmitted directly via the faecal-oral route by parasite eggs containing a larva, it is reasonable to assume that the escalating problem is related to the increased exposure now occurring in modern welfare-friendly cage-free housing systems. On many farms, <em>A. galli</em> reappears in subsequent flocks, even though the birds have no access to the outdoors, biosecurity is high and empty houses are cleaned and disinfected during downtime. Since the egg production cycle lasts only ≈80 weeks and recombinant antigen production for helminth vaccines has not yet been solved, the development of a vaccine seems to be an unrealistic option. Therefore, disrupting the life cycle of the parasite by other means, including the strategic use of dewormers, appears to be the key to controlling infection. Of concern is that only one class of anthelmintics is licenced for poultry in Europe and that are usually administered indiscriminately through the birds' drinking water and often too late when the parasite is already established. If current calendar-based parasite control strategies are not changed, there is a risk that resistance to anthelmintics may develop, as has already been demonstrated with nematodes in livestock. We insist that treatments can be more effective and the risk of developing drug resistance can be mitigated if we invest in a better understanding of <em>A. galli</em> responses to more prudent and judicious use of anthelmintics. This review identifies knowledge gaps and highlights aspects of sustainable parasite control that require further research to support commercial egg producers.</p></div>","PeriodicalId":13775,"journal":{"name":"International Journal for Parasitology: Drugs and Drug Resistance","volume":"23 ","pages":"Pages 1-9"},"PeriodicalIF":4.0,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10409999/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9972010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Droplet digital PCR as a tool to detect resistant isolates of Dirofilaria immitis","authors":"Sohini Kumar ,&nbsp;Roger K. Prichard ,&nbsp;Thavy Long","doi":"10.1016/j.ijpddr.2023.07.002","DOIUrl":"10.1016/j.ijpddr.2023.07.002","url":null,"abstract":"<div><p>Prevention of canine heartworm disease, caused by <em>Dirofilaria immitis</em>, relies on macrocyclic lactones for which drug resistance is now a concern. Although genetic polymorphisms have been associated with resistance in <em>D. immitis</em> populations, the mechanism is still not well understood. The lack of reliable <em>in vitro</em> assays to detect resistance is a limitation for confirming resistance. Ten single nucleotide polymorphisms (SNPs) were previously clinically validated in <em>D. immitis</em> resistant isolates, using the MiSeq platform. This technique although useful for research studies is expensive and does not facilitate rapid detection of these markers in small numbers of clinical samples. We developed a droplet digital PCR protocol for detecting SNPs correlating with ML resistance. Specific primers and hydrolysis probes encompassing the wildtype and mutant alleles were designed to amplify the SNP targets from genomic DNA of different <em>D. immitis</em> isolates. Allele frequencies were determined and the suitability of the ddPCR assay was assessed and compared with MiSeq data. The ddPCR assay accurately detected and quantified alternate nucleotides in two isolates of reference, the ML-susceptible Missouri (MO) and ML-resistant JYD-34, at the previously identified SNP positions. The presence of the SNPs was also determined in additional isolates with known or putative susceptible or resistant phenotypes. We observed SNP1 and SNP2 are more predictive markers and appear suitable for rapid detection and monitoring of drug resistance. Our results suggested that ddPCR could be employed to distinguish infection due to actual genetic resistance from infection with susceptible parasites and also for rapid detection of isolates not only with ML susceptible and resistant genotypes but also mixed genotypes that correspond to heterogeneous isolates containing a mixed population of ML susceptible and resistant parasites. DdPCR may be a useful tool for conducting surveys, or assessments of individual isolates, for genetic evidence of resistance or developing resistance.</p></div>","PeriodicalId":13775,"journal":{"name":"International Journal for Parasitology: Drugs and Drug Resistance","volume":"23 ","pages":"Pages 10-18"},"PeriodicalIF":4.0,"publicationDate":"2023-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/e1/99/main.PMC10407818.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10336518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}