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Summary: Background: Equine anoplocephalid cestodes are tapeworms that occur worldwide in horses and are known to cause pathological manifestations and clinical disease within the digestive system of horses. Objective: While these clinical manifestations and the efficacy of currently available anthelmintics against equine tapeworms have been well documented, a recent study has demonstrated treatment failure of praziquantel and pyrantel pamoate, suggesting resistance; however, this has not been heavily investigated. Study design: This case study examined 24 Thoroughbred yearlings on one Kentucky Thoroughbred horse farm to investigate the elimination of tapeworm eggs after administration of routine anticestodal anthelmintics after confirmation of positive faecal egg counts. Methods: The Mini‐FLOTAC faecal egg counting method was used to count anoplocephalid eggs in yearlings treated with pyrantel pamoate paste (13.2 mg base/kg), moxidectin‐praziquantel (0.4 and 2.5 mg/kg) and ivermectin‐praziquantel (0.2 and 1 mg/kg) over a 6‐month period in 2022. Results: Data demonstrated that tapeworm egg shedding persisted post‐deworming with all three anthelmintic products. Out of the 24 Thoroughbred enrolled, 11/24 (45.8%) had persistent infections in the month of March and 3/24 (12.5%) had persistent infections in April after deworming with ivermectin‐praziquantel. With moxidectin‐praziquantel, 2/24 (8.3%) remained egg count positive. For pyrantel pamoate, 3/24 (12.5%) were detected with tapeworm eggs post‐treatment. During July and August, selected yearlings had faecal sampling done before and 2 weeks post‐deworming with moxidectin‐praziquantel. For July 1/6 (16.7%) horses had tapeworm eggs both before and after deworming, and one additional horse was positive in the post‐treatment sample only. For the August treatment, 4/14 (28.6%) were egg count positive both before and after deworming, with one additional horse being positive in the post‐treatment sample only. Conclusions: This study demonstrated evidence of anthelmintic treatment failure against equine tapeworms by means of regular faecal egg count monitoring. Veterinarians should be aware of this development and implement strategies to monitor anticestodal treatment success. [ABSTRACT FROM AUTHOR]

Bacillus thuringiensis crystal (Cry) proteins have been expressed in commercial transgenic crops for nearly 30 years, providing safe and effective control of insect pests and significantly reducing the application of hazardous chemical pesticides. B. thuringiensis crystal proteins have also been shown to target parasitic nematodes, including plant parasitic nematodes. Recently, transgenic soybean crops expressing Cry14Ab have been shown to provide control against the soybean cyst nematode Heterodera glycines, marking the first time a crystal protein is being commercialized in transgenic crops for control of a nematode pest. However, apart from H. glycines and the free-living nematode, Caenornabditis elegans, the breadth of nematode activity of Cry14Ab, e.g., against gastrointestinal parasitic nematodes (GINs), has not been reported. Here we study the efficacy of Cry14Ab against a wide range of gastrointestinal nematode parasites (GINs) in vitro and in vivo. We find that Cry14Ab is effective in vitro against the barber's pole worm Haemonchus contortus larvae, small strongyles cyathostomin larvae, the hookworm Ancylostoma ceylanicum adults, the roundworm Ascaris suum L4 larvae, and the whipworm Trichuris muris adults. In rodents infected with GIN parasites, Cry14Ab is effective as an in vivo anthelmintic against the hookworms A. ceylanicum and N. americanus, against the mouse parasite Heligmosomoides polygyrus bakeri, and against the roundworm A. suum. Cry14Ab also variably reduces the reproduction of the whipworm T. muris in vivo. Using optimized profile Markov Models, we looked for other putative anthelmintic Cry proteins and, within this list, identified a Bt crystal protein, GenBank accession no. MF893203, that we produced and demonstrated intoxicated GINs. This protein, with 90% amino acid identity to Cry14Ab, is active against C. elegans, A. ceylanicum adults, and A. suum L4 larvae in vitro. MF893203 was given the official designation of Cry14Ac. Cry14Ac is also an effective in vivo anthelmintic against A. ceylanicum hookworms in hamsters and intestinal A. suum in mice. Taken together, our results demonstrate that Cry14Ab and Cry14Ac have wide therapeutic utility against GINs. Author summary: Gastrointestinal parasitic nematodes or worms pose a significant threat to global health, causing illness in millions-billions of people and animals. Current treatments have limitations, including concerns about drug resistance. We are exploring a promising new approach using natural Crystal (Cry) proteins from Bacillus thuringiensis (Bt) bacteria, which are already widely used as safe and effective insecticides. To date, we have focused on the anthelmintic (deworming) properties of Bt Cry protein Cry5Ba. Here, our research demonstrates that a newly characterized and different Bt Cry protein, Cry14Ab, can also effectively target and kill various types of harmful parasitic nematodes in both laboratory and animal models. Moreover, we identify another related Bt protein, Cry14Ac, with similar activities against parasitic nematodes. These findings highlight the potential of Bt proteins as a novel class of deworming medications, offering hope for the development and clinical deployment of safer and more effective treatments against parasitic nematode infections. [ABSTRACT FROM AUTHOR]

Dynamic evolutionary processes and complex structure make the Y chromosome among the most diverse and least understood regions in mammalian genomes. Here, we present an annotated assembly of the male specific region of the horse Y chromosome (eMSY), representing the first comprehensive Y assembly in odd-toed ungulates. The eMSY comprises single-copy, equine specific multi-copy, PAR transposed, and novel ampliconic sequence classes. The eMSY gene density approaches that of autosomes with the highest number of retained X-Y gametologs recorded in eutherians, in addition to novel Y-born and transposed genes. Horse, donkey and mule testis RNAseq reveals several candidate genes for stallion fertility. A novel testis-expressed XY ampliconic sequence class, ETSTY7, is shared with the parasite Parascaris genome, providing evidence for eukaryotic horizontal transfer and inter-chromosomal mobility. Our study highlights the dynamic nature of the Y and provides a reference sequence for improved understanding of equine male development and fertility.

Programmed DNA elimination is a developmentally regulated process leading to the reproducible loss of specific genomic sequences. DNA elimination occurs in unicellular ciliates and a variety of metazoans, including invertebrates and vertebrates. In metazoa, DNA elimination typically occurs in somatic cells during early development, leaving the germline genome intact. Reference genomes for metazoa that undergo DNA elimination are not available. Here, we generated germline and somatic reference genome sequences of the DNA eliminating pig parasitic nematode Ascaris suum and the horse parasite Parascaris univalens. In addition, we carried out in-depth analyses of DNA elimination in the parasitic nematode of humans, Ascaris lumbricoides, and the parasitic nematode of dogs, Toxocara canis. Our analysis of nematode DNA elimination reveals that in all species, repetitive sequences (that differ among the genera) and germline-expressed genes (approximately 1000-2000 or 5%-10% of the genes) are eliminated. Thirty-five percent of these eliminated genes are conserved among these nematodes, defining a core set of eliminated genes that are preferentially expressed during spermatogenesis. Our analysis supports the view that DNA elimination in nematodes silences germline-expressed genes. Over half of the chromosome break sites are conserved between Ascaris and Parascaris, whereas only 10% are conserved in the more divergent T. canis. Analysis of the chromosomal breakage regions suggests a sequence-independent mechanism for DNA breakage followed by telomere healing, with the formation of more accessible chromatin in the break regions prior to DNA elimination. Our genome assemblies and annotations also provide comprehensive resources for analysis of DNA elimination, parasitology research, and comparative nematode genome and epigenome studies.

The article discusses the challenges of evaluating diagnostic tests for neglected tropical diseases (NTDs) and proposes an interpretive framework using Ascaris lumbricoides as an example. The authors argue that using a single "gold standard" reference test can lead to biased estimates of sensitivity and specificity. They recommend using latent class models (LCMs) to analyze data from multiple imperfect tests and account for correlations between test results. The article emphasizes the importance of considering the purpose of testing and the target population when evaluating diagnostic tests for NTDs. The authors provide a graphical illustration to help researchers interpret the results and suggest that the framework should be considered before data collection to modify the combination of tests and populations if necessary. They also highlight the need for further guidance and standardization in diagnostic test evaluation for NTDs. [Extracted from the article]