Assembly and Analysis of Haemonchus contortus Transcriptome as a Tool for the Knowledge of Ivermectin Resistance Mechanisms

Abstract

Haemonchus contortus (Hc) is an important parasitic nematode of small ruminants. In this study we assembled the transcriptome of Hc as a model to contribute to the knowledge about the profile of the differential gene expression between two Mexican Hc strains under different anthelmintic resistance statuses, one susceptible and the other resistant to ivermectin (IVMs and IVMr, respectively), in order to improve and/or to have new strategies of control and diagnosis. The transcript sequence reads were assembled and annotated. Overall, ~127 Mbp were assembled and distributed into 77,422 transcript sequences, and 4394 transcripts of the de novo transcriptome were matched base on at least one of the following criteria: (1) Phylum Nemathelminthes and Platyhelminthes, important for animal health care, and (2) ≥55% of sequence identity with other organisms. The gene ontology (GO) enrichment analysis (GOEA) was performed to study the level of gene regulation to IVMr and IVMs strains using Log Fold Change (LFC) filtering values ≥ 1 and ≥ 2. The upregulated-displayed genes obtained via GOEA were: 1993 (for LFC ≥ 1) and 1241 (for LFC ≥ 2) in IVMr and 1929 (for LFC ≥ 1) and 835 (for LFC ≥ 2) in IVMs. The enriched GO terms upregulated per category identified the intracellular structure, intracellular membrane-bounded organelle and integral component of the cell membrane as some principal cellular components. Meanwhile, efflux transmembrane transporter activity, ABC-type xenobiotic transporter activity and ATPase-coupled transmembrane transporter activity were associated with molecular function. Responses to nematicide activity, pharyngeal pumping and positive regulation of synaptic assembly were classified as biological processes that might be involved in events related to the anthelmintic resistance (AR) and nematode biology. The filtering analysis of both LFC values showed similar genes related to AR. This study deepens our knowledge about the mechanisms behind the processes of H. contortus in order to help in tool production and to facilitate the reduction of AR and promote the development of other control strategies, such as anthelmintic drug targets and vaccines.

Bioactive compounds from the parasitic plant Arceuthobium vaginatum inhibit Haemonchus contortus egg hatching

“…The H. contortus eggs were obtained from an egg-donor lamb (20 kg of bodyweight) previously infected with 7,000 H. contortus L 3 (INIFAP-HcIVMr-SAI strain, Mexico). This isolate was obtained from a naturally infected grazing sheep from a tropical region in the Salto de Agua municipality, Chiapas, Mexico ( González-Garduño et al, 2012 ; Reyes-Guerrero et al, 2023 ). The lamb was housed indoors on a metabolic floor, feed hay and commercial concentrate and had free access to water.…”

Quantifying the fitness effects of resistance alleles with and without anthelmintic selection pressure using Caenorhabditis elegans

“…To date, ivermectin resistance across Nematoda appears to involve various genes and mechanisms [66,[68][69][70]. Additional genes outside of those that encode for GluCl subunits are implicated in the MoR of ivermectin, which includes Dyf genes and genes involved in neuronal development and function, such as unc-7, unc-9, unc-38, and unc-63 [98][99][100][101].…”

“…Nevertheless, it is essential to note that the mutagenesis studies in C. elegans were not performed in a controlled background and assessed only one trait, survival, as measured by placing embryos on agar plates with ivermectin and observing the number of embryos that grew to adulthood [64,66]. Because many genes, as shown by others [66][67][68][69][70][71][72][73][74] and outlined below, can cause ivermectin resistance, a controlled genetic background is essential. The Dent study performed screens in 10 ng/ml of ivermectin on Nematode Growth Medium (NGM) plates with animals in an avr-15 mutant background.…”

Advances in the Control of the Helminthosis in Domestic Animals

“…Diagnostic. Reyes-Guerrero et al mentioned that their study deepens our knowledge about the mechanisms behind the processes of Haemonchus contortus in order to help in tool production and to facilitate the reduction in anthelmintic resistance and promote the development of other control strategies, such as anthelmintic drug targets and vaccines [ 5 ]. Phytotherapy.…”