In vivo anthelmintic activity of Combretum mucronatum schumach & Thonn leaf extract against Haemonchus contortus in goats

Parasitic infections with gastrointestinal nematodes are a serious problem for the health and welfare of domestic animals and negatively affect the economics of animal production. Haemonchus contortus is a haematophagous nematode of small ruminants responsible for significant mortality and morbidity. In addition, the widespread resistance to synthetic anthelmintic drugs emphasizes the urgent need of alternative treatment options against haemonchosis. This work aims to investigate the anthelmintic activity of an hydroethanolic Combretum mucronatum leaf extract (CMLE) against Haemonchus contortus in goats. Goats were artificially infected with 3500 third-stage larvae of H. contortus, and 21 days later, treated with CMLE (1000, 500, 250 mg/kg) for 4 consecutive days. Different parameters such as faecal egg count reduction, weight and haematocrit were monitored during the experimental period. The number of eggs per gram of faeces (EPG) was concentration-depended lower and significantly reduced compared to the untreated control (p < 0.0001). The effect of the highest CMLE dose (4 ×1000 mg/kg body weight) was similar to the effect of albendazole (1 ×5 mg/kg of body weight). The ED50 and ED90 values calculated were 189.17 and 392.33 mg/kg body weight respectively. ED50 and ED90 values were time-dependent. Moreover, CMLE improved haematocrit and weight of goats in dose-dependent and time-dependent manner. These results showed that CMLE could be used for haemonchosis treatment in small ruminants.

Divergent humoral responses between males and females against 24 kDa excretory-secretory protein of Haemonchus contortus and influence of ovine β-globin polymorphism

Lambs harboring the Hb-AA β-globin haplotype present improved cell-mediated responses and increased resistance against Haemonchus contortus infection. The aim of the present study was to compare the effect of sex and β-globin haplotypes on specific humoral responses and phenotypes of resistance during H. contortus infection in Morada Nova sheep. As expected, females displayed stronger resistance during the first and second experimental challenges. Differential systemic humoral immune responses were observed comparing sex groups, in which higher levels of specific antibodies targeting 24 kDa excretory-secretory (ES24) protein of H. contortus of IgG and IgM antibodies were respectively observed as predominant isotypes in males and females. The IgM levels were significantly correlated with phenotypes of resistance, evaluated by packed cell volume and fecal egg counts. To our knowledge this is the first study reporting divergent humoral responses profiles to H. contortus infection between male and female sheep. The impact of β-globin haplotypes was less pronounced in females compared to males. Notably, only males showed significant weight differences across haplotypes, with Hb-AA lambs being the heaviest. Additionally, Hb-AA males had significantly higher PCV (indicating better red blood cell health) and lower FEC (indicating lower parasite burden). These findings suggest a more pronounced effect of β-globin polymorphisms on H. contortus infection in males, potentially due to their generally weaker resistance compared to females. This study highlights the importance of sex and β-globin haplotypes in shaping immune responses to H. contortus infection. Specifically, IgM antibodies targeting the ES24 protein appear to play a crucial role in host-parasite interactions and may hold promise for therapeutic development.

Prevalence status and detection of benzimidazole resistance using AS-PCR in Haemonchus contortus of goats from Marathwada region, Maharashtra, India

This study examined Haemonchus contortus prevalence and benzimidazole resistance in eight districts of Marathwada, Maharashtra, India. A comprehensive investigation of 264 abomasa of goats collected from abattoirs and goats necropsied at the College of Veterinary Sciences and Animal Husbandry, Parbhani, revealed 21.21 % a prevalence of H. contortus. The incidence of H. contortus did not vary much across seasons and it was highest in summer (23.42 %), followed by monsoon (22.89 %), and lowest in winter (15.71 %). Statistically non-significant (p < 0.05) prevalence was observed in male and female animals. A detailed examination of 168 adult H. contortus worms from eight districts revealed the presence of all conceivable genotypes including homozygous resistant (rr), susceptible (SS), and heterozygous (Sr) BZ susceptible genotypes. The rr was the most frequent at 50 %, followed by SS at 27 % and Sr at 22 %. The presence of the SNP was observed in in all eight randomly selected and sequenced samples.

Efficacy of a Haemonchus contortus vaccine under field conditions in young alpacas

Anthelmintic resistance to Haemonchus contortus creates increasing management challenges with small ruminants and camelids. The commercial vaccine, Barbervax®, contains H11 and H-gal-GP antigens, derived from gut mucosal membrane enzymes of H. contortus involved in digesting blood. Antibody neutralization of these antigens causes failure of H. contortus to digest blood, resulting in parasite death. H11 and H-gal-GP are considered "hidden" antigens, meaning the host immune system does not encounter these proteins under natural infection. Therefore, repeat immunization is required to maintain protective humoral responses. One previous study evaluated the safety of Barbervax® in camelids but the efficacy could not be assessed due to lack of successful infection in the controls. The objective of the current study was to evaluate clinical parameters of anemia, fecal egg counts (FECs), and humoral immune responses of healthy alpacas after immunizing with Barbervax® compared to non-vaccinated controls, all under natural environmental exposure on parasite-laden pastures. A crossover-like study was performed where twenty alpacas (298 ± 66 days of age) were assigned to be initially vaccinated with Barbervax® (n=10) or receive no treatment (n=10). Three doses of Barbervax® were administered at three-week intervals. Feces and blood were collected on Day -10, 0, 21, 43, 64, 85, 106, and 135 to evaluate FECs, packed cell volume (PCV), and antibody titers. Each group was kept on separate adjacent pastures. Tracer sheep (n=2 per study group) were introduced on Day 43 for a three-week period to ensure parasite acquisition. For the crossover-like component on Day 85, the initial non-vaccinated group was administered Barbervax® with dosing repeated on Day 106 and 135. Results indicated all initially vaccinated alpacas produced antibody titers to vaccine antigen that corresponded to lower mean FECs compared to the initially non-vaccinated group. A reduced mean FEC in the vaccinate group was observed 21 days after peak antibody titers. Similarly, when pooled vaccinate antibody titers were noted to wane on Day 106, an increase in FEC was observed at the following time point (Day 135). Conclusions from our study support the use of Barbervax® to reduce H. contortus burdens in alpacas. Furthermore, a less than 30-day lag time between antibody titer and resultant effect in FECs was observed. Additional studies assessing the ability of Barbervax® to reduce H. contortus burdens during subsequent grazing seasons would provide even greater information regarding the use of Barbervax® within alpaca herds to modulate H. contortus infections, refugia, and anthelmintic use.

Haemonchus contortus alters distribution and utilization of protein and amino acids in different tissues of host sheep

The objective was to determine host animal protein/amino acid redistribution and use among the abomasum, duodenum and muscle of sheep infected with Haemonchus contortus. Sixteen male Ujumqin sheep (32.4 ± 3.9 kg) were dewormed and randomly assigned to two groups, infected or not infected with H. contortus (GIN and CON). The GIN group had lower (P < 0.05) dry matter intake, average daily gain, and live body weight than CON, with extensive focal infiltration of lymphocytes in the lamina propria and bottom of the abomasal epithelium. In the abomasum and duodenum, there were 100 and 220 genes, respectively, that were up-regulated, whereas 56 and 149 were down-regulated. In the abomasum, the most enriched KEGG pathways were related to immunity and inflammation reaction, including: viral protein interaction with cytokine and cytokine receptor (P = 0.017), influenza A (P = 0.030), IL-17 signaling pathway (P = 0.030). In the duodenum, KEGG pathways were more enriched in nutrient metabolism, including pancreatic secretion (P < 0.001), protein digestion and absorption (P < 0.001), graft-versus-host disease (P = 0.004). Furthermore, most genes related with the above KEGG pathways were increased in the abomasum but decreased in the duodenum. Amino acid profiles in abomasum and duodenum of CON and GIN groups were clustered in a partial least-squares discriminant analysis model, with significant changes in 36 and 19 metabolites in abomasal and duodenal chyme, respectively. Further confirmed by transcriptome-targeted metabolome association analysis, GIN mainly enhanced metabolism of arginine and sulphur amino acids in abomasum and those metabolic pathways were associated. Meanwhile, GIN mainly decreased pyruvate related amino acid metabolism in duodenum. Moreover, concentrations of Arg (P = 0.036), His (P = 0.027), and Cys (P = 0.046) in longissimus thoracis et lumborum were decreased in GIN, whereas concentrations of Gly (P = 0.012) and Ala (P = 0.046) were increased. In conclusion, H. contortus enhanced metabolism of arginine and sulphur amino acids in the abomasum; decreased pyruvate metabolism in the duodenum; and drove more protein/amino acids for abomasal tissues to resist physical and immune damage, reducing protein and amino acids in duodenum and muscle for support host growth. Specific nutrients (such like arginine, histidine, and cysteine) may play important role in control gastrointestinal nematode infection for ruminant.

Molecular study of the transcription factor SKN-1 and its putative relationship with genes that encode GST and antioxidant enzymes in Haemonchus contortus

Haemonchus contortus is a parasitic nematode of ruminants. Once inside its host, it is exposed to reactive oxidative species and responds by synthesising antioxidant enzymes as a defence. In Caenorhabditis elegans, antioxidant genes are regulated by the transcription factor skinhead-1 (Cel-SKN-1). However, there is little information about the function of SKN-1 in H. contortus (Hco-SKN-1). Therefore, we performed a molecular investigation to characterise Hco-SKN-1 and its putative relationship with genes encode antioxidant enzymes, namely glutathione S-transferases (Hco-GSTs, n = 3), superoxide dismutase (Hco-SOD) and catalase (Hco-CAT), which are involved in haematophagy and defence against the host. We used in silico sequence analysis of Hco-SKN-1 and Hco-GSTs to design and perform relative expression assays involving H. contortus eggs, infective larvae (L3) and adults. Furthermore, we exposed H. contortus transitional infective larvae (xL3) to erythrocytes or hydrogen peroxide (H2O2) and evaluated the relative expression of antioxidant genes at 24 or 48 h. Gene Ontology (GO) analysis revealed 31 functions associated with Hco-SKN-1 and Hco-GSTs, including stress resistance, larval development and the active immune response. Hco-GST-5957 and Hco-SOD showed the highest expression in adults, indicating a relationship with specific functions at this mature stage. xL3 exposed to erythrocytes or H2O2 showed significant upregulation of Hco-SKN-1, but it occurred after upregulation of the antioxidant genes, indicating that these genes are not regulated by Hco-SKN-1 during the blood-feeding stage. Additional investigation is necessary to understand the putative regulation of antioxidant genes by Hco-SKN-1 during the blood-feeding stage.

Molecular signatures of Haemonchus contortus infection in sheep: A comparative serum proteomic study on susceptible and resistant sheep breeds

Due to the negative impact of Haemonchus contortus in the tropics and subtropics, the detection of serum protein profiles that occur in infected sheep is of high relevance for targeted selective treatment strategies (TST). Herein, we integrated proteomics with phenotypic traits to elucidate physiological mechanisms associated to H. contortus infection in susceptible (Dorper - D) and resistant (Santa Inês - S) sheep breeds. Naïve female lambs were infected with H. contortus third-stage larvae on day zero (D0), and samples were collected weekly, for 28 days. Feces were used for individual fecal egg counts (FEC) blood for packed cell volume (PCV) and serum for specific antibody quantification through ELISA. Sera was collected on D0 (-) and D21 (+), and analyzed using a LC-MS/MS based proteomics approach. FEC, PCV, and anti-H. contortus antibody levels confirmed the absence of infection on D0. On D28 there was a significant difference between the two breeds for logFEC means (D = 3774 and S = 3141, p=0.033) and PCV means (D = 16.3 % and S = 24.3 %, p=0.038). From a total of 754 proteins identified, 68 differentially abundant proteins (DAPs) were noted. Phosphopyruvate hydratase (ENO3) was a DAP in all comparisons, while S+ vs D+ and S- vs D- shared the highest number of DAPs (8). Each of the four experimental groups clustered separately in a principal component analysis (PCA) of protein profile. Among the DAPs, proteins associated with the innate and adaptive immune system were detected when comparing S- vs D- and S+ vs D+. In D-, some proteins were linked to stress response to handling, sampling and heat. Focusing on the consequences of infection in each breed, in the D+ vs D- comparison, upregulated proteins were associated with inflammation control and immune response, where downregulated proteins pointed to a negative impact of infection on tissue anabolism, compromising muscle growth and fat deposition. In the S+ vs S- comparison, upregulated proteins were related to immune response, while the downregulated proteins were possibly linked to muscular development and growth, impaired by infection. Collectively, it can be concluded that ENO3 regulation emerges as a potential factor underlying the differential immune response observed between Santa Inês and Dorper sheep infected with H. contortus. In turn, detected acute phase proteins (APPs) reinforce their relation with infection, inflammation and stress conditions, whereas THEMIS-like may contribute to the immune system in Dorper. GSDMD, Guanylate-binding protein and ACAN warrant further investigation as possible biomarkers for TST strategy development.

Expression of Toll-like receptors in Haemonchus Contortus resistant sheep: An innate immune parameter for host defense against gastrointestinal nematode infection

Innate immune parameters, a first line of defense against invading pathogens like bacteria, parasites, fungi, etc, play a significant role in the prevention and elimination of aetiological agents primarily by recognition of invading pathogen-specific molecules by different pattern recognition receptors. Toll-like receptors (TLRs), a type-I transmembrane glycoprotein, cause innate immune responses mainly by produing inflammatory cytokines, chemokines and interferons. The objective of present study was to determine the role of TLRs in parasite resistance in Malpura sheep. In the current study, transcript variation of TLRs and its downstream signalling molecules namely MyD88, TRIF, IRF-3, TRAF, TGF-β, NFκB, and CD14 were ascertained by real-time PCR in Haemonchus contortus resistant (R) and susceptible (S) Malpura sheep. Results have shown significantly (P<0.05) up-regulated expression of TLR-2, TLR-4, TLR-5, TLR-8 and TLR-10 in July however down-regulated patterns were observed in August and September in R-line sheep compared to S-line sheep. This indicates that at more or less equal parasite load, the TLR genes in R sheep produce more transcripts, but after parasite loads have increased hugely in the S line, they easily surpass the levels seen in the S line. Result suggests that transcriptional activity of the TLR genes was related to parasite load and there were differences between the lines at different infection intensities. Three-point transcript expression observation of the signalling molecules namely TRIF, IRF-3, TRAF, a similar pattern was observed in R sheep compared with S sheep.

The first molecular detection of benzimidazole resistance in Haemonchus contortus from sheep in Hejing and Minfeng counties of Southern Xinjiang

To understand the benzimidazole (BZ) resistance of Haemonchus contortus in Southern Xinjiang, three single nucleotide polymorphisms (SNPs) designated as F167Y, E198A, and F200Y, in the isotype-1 β-tubulin gene which are associated with BZ resistance, were investigated for H. contortus populations from sheep in Hejing and Minfeng counties of Southern Xinjiang. In brief, a total of 190 H. contortus adults were collected from 52 out of 70 slaughtered sheep in city abattoirs across two regions in Southern Xinjiang. The species identity of each adult worm was confirmed by PCR amplification of ITS-2 using H. contortus-specific primers targeting the ITS-2. The samples were then investigated for BZ-related SNPs at locus 167, 198, and 200, by PCR-sequencing of the isotype-1 β-tubulin gene. The results showed that only E198A and F200Y mutations were detected in the investigated H. contortus populations. The E198A mutation (homozygous and heterozygote resistant: found in 40% and 30% of sequenced samples from Minfeng and Hejing counties, respectively) was predominant compared with the F200Y mutation (homozygous and heterozygote resistant: found in 14% and 13.3% of sequenced samples from Minfeng and Hejing counties, respectively). The results indicate a high prevalence of BZ resistance in H. contortus populations from certain areas of Southern Xinjiang. Our findings provide valuable information for the prevention and control of H. contortus in areas with similar conditions.

Rodents Used for the Propagation of Hookworms and Haemonchus contortus

Helminthiasis due to hookworm infestations in humans and Haemonchus contortus in sheep cause untold levels of disease and economic losses worldwide. Drug resistance is an ever-growing problem with pathogenic helminths. Thus, there is a critical need for new treatment strategies for hookworms and H. contortus that depends on animal models. Because hook- worms and H. contortus are obligate parasites, they can only be maintained using live animals. This review describes use of the Syrian golden hamster to propagate hookworms and Mongolian gerbil to propagate H. contortus.

Beyond parasitism: Exploring the microbial profile of Haemonchus contortus and its predilection site (abomasum) in Kashmir Merino sheep

Gastrointestinal helminth infection, particularly by Haemonchus contortus, poses significant challenges to sheep farming worldwide. While anthelmintic drugs have been traditional control measures, the emergence of resistance calls for alternative strategies. Understanding the interaction between parasites, host, and their microbiome is crucial for management of helminth infection. This study intricately explores the interactions between microbial communities in Kashmir Merino sheep infected with H. contortus, to understand the complex interplay between host, parasite, and their microbiome. Sheep abomasal contents and H. contortus were collected from infected and control groups, processed for DNA extraction, and subjected to metagenomic sequencing of the 16 S rRNA gene. Downstream analysis unveils distinct microbial patterns, where Proteobacteria were dominant in H. contortus, while Bacteroidota and Firmicutes prevailed in the sheep abomasum. The revelation of unique genera and shifts in diversity indices underscored helminth-induced disruptions in the host. Beta diversity analysis further showed significant variations in bacterial profiles, providing insights into the intricate host, parasite, and microbiome dynamics. Additionally, this study elucidated the presence of pathogenic bacteria within H. contortus, accentuating their potential role in exacerbating sheep health issues. This finding underscores the complexity of the host-parasite-microbiome interaction showing helminth-induced microbiome alterations of the host.

High rates of benzimidazole-resistance-associated alleles in Haemonchus contortus and detection of resistance against macrocyclic lactones in strongylids from German alpaca herds

The population of South American camelids (SAC) has been steadily growing in Europe, where they are confronted with the regional endoparasite population of ruminants. As there are no anthelmintic drugs registered for use against nematode infections in SACs, anthelmintics (AH) available for ruminants or horses are usually applied. Reports indicating potential failures in administered AH are increasing. However, the generally low egg counts in SACs complicate the application of resistance tests in the field. The present study reports a follow-up study on SAC farms where anthelmintic resistance (AR) was suspected. The aims were (i) to repeat faecal egg count reduction tests (FECRTs) on potentially affected farms identified in a previous study with larger sample sizes, (ii) to verify suspected AR of Haemonchus contortus against benzimidazoles (BZ) by performing a single-nucleotide polymorphism (SNP) analysis using digital polymerase chain reaction (dPCR), and (iii) to apply the mini-FLOTAC technique for more reliable results at low egg counts in line with current recommendations. Seven farms (9-46 animals each) were examined by coproscopy, larval differentiation and SNP analysis. A FECRT was performed on six of these farms with moxidectin (three farms), monepantel (two farms) and ivermectin (one farm). The FEC was calculated according to the current World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines with the clinical protocol (a newly introduced variant of FECRT which can be used for smaller sample sizes and lower egg counts on the cost of sensitivity) and an expected efficacy of 99%. A high level (> 90%) of BZ-resistance-associated SNPs on codon 200 of H. contortus was observed on all farms. With the FECRT, resistance was demonstrated for ivermectin (74% FECR), while it remained inconclusive for one farm for moxidectin treatment. Sustained efficacy was demonstrated for the remaining treatments. This study showed an advanced level of BZ resistance in H. contortus of SACs and the development of AR against macrocyclic lactones on some farms. Thus, constant monitoring of AH treatment and sustainable worm control methods both need to be applied.

Regulatory effect of Balanites aegyptiaca ethanol extract on oxidant/antioxidant status, inflammatory cytokines, and cell apoptosis gene expression in goat abomasum experimentally infected with Haemonchus Contortus

This experiment aimed to assess the regulatory effects of treatment with Balanites aegyptiaca fruit ethanol extract (BA-EE) on oxidant/antioxidant status, anti-inflammatory cytokines, and cell apoptosis gene expression in the abomasum of Haemonchus contortus-infected goats. Twenty goat kids were assigned randomly to four equal groups: (G1) infected-untreated, (G2) uninfected-BA-EE-treated, (G3) infected-albendazole-treated, (G4) infected-BA-EE-treated. Each goat in (G1), (G3), and (G4) was orally infected with 10,000 infective third-stage larvae. In the fifth week postinfection, single doses of albendazole (5 mg/kg.BW) and BA-EE (9 g/kg.BW) were given orally. In the ninth week postinfection, the animals were slaughtered to obtain abomasum specimens. The following oxidant/antioxidant markers were determined: malondialdehyde (MDA), glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT). The mRNA gene expression of cytokines (IL-3, IL-6, IL-10, TNF-α) and cell apoptosis markers (Bax, Bcl-2) were estimated. (G1) showed significantly reduced GSH content and GST and SOD activities but a markedly increased MDA level. (G3) and (G4) revealed a markedly lower MDA level with pronouncedly elevated GSH, SOD, and GST levels. The antioxidant properties of BA-EE were superior to those of albendazole. The mRNA gene expressions of IL-3, IL-6, IL-10, TNF-α, and Bax-2 were upregulated in (G1) but downregulated in (G3) and (G4). Bcl-2 and Bcl-2/Bax ratio expression followed a reverse course in the infected and both treated groups. We conclude that BA-EE treatment has a protective role in the abomasum of H. contortus-infected goats. This could be attributed to its antioxidant properties and ability to reduce pro-inflammatory cytokines and cell apoptosis.

Comparison of P-glycoprotein gene expression of two Haemonchus contortus isolates from Yucatan, Mexico, with resistant or susceptible phenotype to ivermectin in relation to a susceptible reference strain

The variability in the expression of different P-glycoprotein (P-gp) genes in parasitic nematodes of ruminants such as Haemonchus contortus (Hco-pgp) may be caused by different factors including nematode biology, geographical region and anthelmintic pressure. This study analysed the relative expression level of 10 P-gp genes in two H. contortus (Hco-pgp) field isolates from Yucatan, Mexico: 1) PARAISO (IVM-resistant) and 2) FMVZ-UADY (IVM-susceptible). These isolates were compared with a susceptible reference isolate from Puebla, Mexico, namely "CENID-SAI". In all cases H. contortus adult males were used. The Hco-pgp genes (1, 2, 3, 4, 9, 10, 11, 12, 14 and 16) were analysed for each isolate using the RT-qPCR technique. The Hco-pgp expressions were pairwise compared using the 2-ΔΔCt method and a t-test. The PARAISO isolate showed upregulation compared to the CENID-SAI isolate for Hco-pgp 1, 3, 9, 10 and 16 (P < 0.05), and the PARAISO isolate showed upregulation vs. FMVZ-UADY isolate for Hco-pgp 2 and 9 (P < 0.05), displaying 6.58- and 5.93-fold differences (P < 0.05), respectively. In contrast, similar Hco-pgp gene expression levels were recorded for FMVZ-UADY and CENID-SAI isolates except for Hco-pgp1 (P <0.1), which presented a significant upregulation (6.08-fold). The relative expression of Hco-pgp allowed confirming the IVM-resistant status of the PARAISO isolate and the IVM-susceptible status of the FMVZ-UADY isolate when compared to the CENID-SAI reference isolate. Therefore, understanding the association between the Hco-pgp genes expression of H. contortus and its IVM resistance status could help identifying the genes that could be used as molecular markers in the diagnosis of IVM resistance. However, it is important to consider the geographic origin of the nematode isolate and the deworming history at the farm of origin.

In vitro ovicidal and larvicidal activity of a hydroalcoholic extract and its fractions from Cyrtocarpa procera fruits on Haemonchus contortus

This study describes the in vitro anthelmintic effect of a hydroalcoholic extract (HA-E) and its fractions from Cyrtocarpa procera fruits against Haemonchus contortus eggs and infective larvae. The HA-E was subjected to bipartition using ethyl acetate, which resulted in an aqueous fraction (Aq-F) and an organic fraction (EtOAc-F). The HA-E and both fractions were tested using the egg hatching inhibition assay (EHIA) and the larval mortality test (LMT). Fractionation of the EtOAc-F was achieved using different chromatographic processes, i.e., open glass column and HPLC analysis. Fractionation of the EtOAc-F gave 18 subfractions (C1R1-C1R18), and those that showed the highest yields (C1R15, C1R16, C1R17 and C1R18) were subjected to anthelmintic assays. The HA-E and the EtOAc-F displayed 100% egg hatching inhibition at 3 and 1 mg/mL, respectively, whereas Aq-F exhibited 92.57% EHI at 3 mg/mL. All subfractions tested showed ovicidal effect. Regarding the larval mortality test, HA-E and EtOAc-F exhibited a larvicidal effect higher than 50% at 50 and 30 mg/mL, respectively. The subfractions that showed the highest larval mortality against H. contortus were C1R15 and C1R17, with larval mortalities of 53.57% and 60.23% at 10 mg/mL, respectively. Chemical analysis of these bioactive subfractions (C1R15 and C1R17) revealed the presence of gallic acid, protocatechuic acid, and ellagic acid. This study shows evidence about the ovicidal and larvicidal properties of C. procera fruits that could make these plant products to be considered as a natural potential anthelmintic agents for controlling haemonchosis in goats and sheep.

In vitro and in vivo anthelmintic effect of essential oil obtained from Thymus capitatus flowers against Haemonchus contortus and Heligmosomoides polygyrus

Sheep haemonchosis is a disease that causes serious losses in livestock production, particularly with the increase of cases of anthelmintic resistance around the world. This justifies the urgent need of alternative solutions. The aim of this study was to determine the chemical profile, in vitro, and, in vivo, anthelmintic properties of Thymus capitatus essential oil. To evaluate the, in vitro, anthelmintic activity of the T. capitatus EO on Haemonchus contortus, two tests were used: egg hatch assay (EHA) and adult worm motility (AWM) assay. The nematicidal effect of this oil was evaluated, in vivo, in mice infected artificially with Heligmosomoides polygyrus using faecal egg count reduction (FECR) and total worm count reduction (TWCR). Chromatographic characterization of T.capitatus composition using gas chromatography coupled to mass spectrometry (GC-MS) demonstrated the presence of carvacrol (81.16%), as the major constituents. The IC50 values obtained was 1.9 mg/mL in the EHT. In the AWM assay; T. capitatus essential oil achieved 70.8% inhibition at 1 mg/mL after 8 h incubation. The in vivo, evaluation on H. polygyrus revealed a significant nematicidal effect 7 days post-treatment by inducing 49.5% FECR and 64.5% TWCR, using the highest dose (1600 mg/kg). The results of present study, demonstrate that T.capitatus EO possess a significant anthelmintic properties. Furthermore, it could be an alternative source of anthelmintic agents against gastrointestinal infections caused by H. contortus.

An alkaloidal fraction of Annona tomentosa possesses anthelmintic activity and induces surface modifications in Haemonchus contortus

The nematode Haemonchus contortus is, as a parasite, responsible for most mortality of small ruminants, causing significant economic losses. Numerous plant-derived compounds have exhibited promising anthelmintic activities against this nematode. Notably, the Annona genus stands out for demonstrated anthelmintic effects by extracts from several of its species against different nematodes. This study aimed to assess the effect of an Annona tomentosa fraction, rich in alkaloids, on H. contortus. This fraction, named Alk.F, is derived from the methanolic extract of the plant's stem bark. Chemical characterization of Alk.F was performed by liquid chromatography coupled with mass spectrometry. Among the nine predominant peaks obtained, seven alkaloids were identified: reticuline, reticuline N-oxide, reticuline N-oxide isomer, cyclanoline, asimilobine, tetrahydropalmatine and anonaine. Alk.F inhibited the larval development of H. contortus with an IC50 of 0.026 mg/mL, inhibited larval exsheathment with an IC50 of 0.38 mg/mL, and displayed low hemolytic activity towards sheep erythrocytes. Furthermore, atomic force microscopy revealed that Alk.F altered adhesive forces and the height profile on the surface of H. contortus larvae. In conclusion, A. tomentosa alkaloids alter the cuticle structure of H. contortus, inhibiting larval development and exsheathment, thus offering possibilities for contributing to the development of new anthelmintic drugs.

Synergistic Interaction Effect of Artemisia cina n-hexane Extract and Tagetes lucida Ethyl Acetate Extract on Haemonchus Contortus

PURPOSE

We analysed the possible synergistic activity among active extracts from Artemisia cina and Tagetes lucida combinations on Haemonchus contortus, a nematode parasitising sheep.

METHODS

The work was carried out in vitro on eggs and infective larvae (L3) of H. contortus. The results were analysed with SAS 9.1, applying the ANOVA and Tukey test, and the lethal concentration (LC) values LC50 and LC90 were determined with regression analysis, employing Proc Probit of SAS 9.1. Additionally, the lethal concentration (LC) was calculated with LC50 and LC90 to determine the synergistic effect.

RESULTS

The results demonstrated a high efficacy of the two plants studied on both nematode eggs and L3 larvae as well as of their combinations. The highest egg hatching inhibition was obtained with a 50/50 combination, and the best larvae mortality was obtained with 25% A. cina and 75% T. lucida at 10 mg/mL. Additionally, this combination showed a synergistic effect.

CONCLUSION

The two plant species studied here can be applied as natural anthelmintic alternatives due to their high bioactive effect and synergistic response.

Reducing fecal egg count through selective breeding alters dorper lamb response to Haemonchus contortus in an artificial challenge trial

Infection by gastrointestinal nematodes (GIN), particularly Haemonchus contortus, can be detrimental to sheep health and performance. Genetic susceptibility to GIN varies between breeds, with those lacking high levels of natural resistance often requiring frequent anthelmintic treatment when facing parasitic challenge. Genetic technology can serve as a tool to decrease GIN susceptibility via selection for sheep with reduced fecal egg count (FEC) estimated breeding values (EBVs). However, the physiological changes that result from implementation of this strategy are not well described. Additionally, there is a need for comparison of animals from recent selective breeding against breeds with inherent GIN resistance. In this study we administered a challenge of H. contortus to Dorper x White Dorper (DWD; n = 92) lambs that have been genetically selected for either low (DWD-) or high (DWD+) FEC EBVs and Barbados Blackbelly x Mouflon (BBM; n = 19) lambs from a genetically resistant breed backgrounds. Lamb FEC, packed-cell volume (PCV) and serum IgG were measured at intermittent levels over 5 weeks. At day 21 and day 35, the selectively bred DWD- had a lower mean FEC compared to DWD+, but were higher than BBM. Reductions in both PCV and serum IgG from initial day 0 levels were observed in DWD lambs, but not in BBM. Furthermore, from a subset of lambs (n = 24) harvested at day 21, DWD- only tended (p = 0.056) to have lower mean worm counts than DWD+, with BBM having the lowest mean worm count. Differentially expressed genes (DEGs) identified via RNA-sequencing of abomasal tissue at day 21 indicate a more pronounced Th2 immune response and more rapid worm expulsion occurred in iBBM than iDWD- and iDWD+ lambs. However, gene expression in DWD- suggests an association between reduced FEC EBV and gastric acid secretion and the ability to limit worm fecundity. Ultimately, selection of Dorper sheep for low FEC EBV can reduce susceptibility to GIN, but it will likely require multiple generations with this trait as a breeding priority before presenting a similar resistance level to Caribbean breeds.

The in vitro rumen exsheathment test for studying the effect of plant extracts on the exsheathment of Haemonchus contortus infective larvae

This study applied the in vitro rumen exsheathment test (IVRET) to evaluate the exsheathment kinetics of Haemonchus contortus infective larvae (L3) incubated in ruminal liquor (RL) containing acetone:water extracts of Acacia pennatula (AP), Gymnopodium floribundum (GF), Havardia albicans (HA) or Lysiloma latisiliquum (LL). The role of polyphenols in the biological activity of the evaluated extracts was also determined. Larvae were incubated in RL either alone or added with a different plant extract (AP, GF, HA, or LL) at 1200 μg/mL. Polyethylene glycol (PEG) was added to block polyphenols in each treatment (RL+PEG, AP+PEG, GF+PEG, HA+PEG, and LL+PEG). After incubation times of 0, 1, 3, 6, 9, and 24 h, the exsheathment process was stopped to count the number of ensheathed and exsheathed L3. A Log-Logistic model was used to determine the L3 exsheathment kinetics in the different RL treatments. The inflection point of the respective kinetic curves, which indicates the time to reach 50 % exsheathed L3 (T50), was the only parameter that differed when comparing the exsheathment models (99 % probability of difference). The T50 values obtained for GF, HA, and LL treatments (T50 = 7.11 - 7.58 h) were higher in comparison to the T50 of RL (5.72 h) (≥ 70 % probability of difference). The L3 incubated in RL added with GF, HA, and LL extracts delayed their exsheathment at 3 and 6 h of incubation (28.71 - 48.06 % exsheathment reduction) compared to the RL treatment. The T50 value for AP, AP+PEG, GF+PEG, HA+PEG, and LL+PEG were similar to RL and RL+PEG (T50 = 5.34 - 6.97 h). In conclusion, the IVRET can be used to identify plants with the potential to delay the exsheathment of H. contortus L3 in the ruminal liquor. The acetone:water extracts of G. floribundum, H. albicans, and L. latisiliquum delayed the T50 of H. contortus exsheathment, which was evident at 3 and 6 h of incubation in ruminal liquor. The observed exsheathment delay was attributed to the polyphenol content of the extracts.

Variants of NLRP3 Protein in Haemonchus contortus Infected Sheep: Impact on Immune Cell Responsiveness to LPS In Vitro

Pathogen recognition is an essential component to achieve the desired outcome of host protection. Nod-like receptor pyrin containing domain 3 (NLRP3) is a cytoplasmic pattern recognition receptor (PRR) with a wide array of agonists, such as PAMPs, DAMPs, ATP, bacterial product and viral products. Stimulation of the NLRP3 inflammasome results in proteolytic activation of IL-1β and IL-18, cell pyroptosis and classically, the induction of proinflammatory responses. St. Croix (STC) sheep have resistance traits exhibiting the appropriate T-helper type 2 immune response ensuing protection during helminth parasitic infection whereas parasite-susceptible Suffolk (SUF) sheep have an impaired response resulting in parasite establishment and adverse symptoms. The objective of these experiments was to determine if NLRP3 protein in H. contortus-infected SUF sheep was defective using the classical activation pathway of NLRP3 inflammasome. Peripheral blood mononuclear cells (PBMCs) derived from H. contortus-infected STC and SUF sheep were isolated from whole blood and treated (MCC950 treatment for 2 h followed by LPS treatment for 3 h, 1400 W treatment for 2 h followed by LPS treatment for 3 h, LPS treatment for 3 h or culture media for 3 h). qPCR analysis of LPS-stimulated PBMC revealed an upregulation in inflammatory associated genes IL-1β, TLR4, TNFα and NFκB (p < 0.0001) in STC PBMC and downregulation in IFNγ, IL-6 and iNOS for SUF PBMC. Pharmacological inhibition of iNOS in SUF PBMC resulted in an upregulation in the expression of IFNγ. These preliminary data begin to discover a relationship between NLRP3 activation and TLR4 signalling in PBMC of STC and SUF sheep.

Growth hormone stimulates the in vitro development and establishment of Haemonchus contortus in sheep

The physiologic increase in some sex hormones has been associated with an increase in the parasite load caused by Haemonchus contortus in ewes, especially prolactin. In lambs that are especially susceptible to hemonchosis, the levels of sex hormones are low; in contrast, the levels of another pituitary hormone, growth hormone (GH), which is structurally very similar to prolactin, are high. In this study, the in vitro and in vivo effects of GH on H. contortus larvae development and establishment were evaluated. The addition of 20 ng/mL GH for 5 and 10 days to cultures of H. contortus larvae induced an enlargement (p<0.01) and an L3/L4 molting rate (p<0.03) greater than that of untreated larvae or those treated with other concentrations of the hormone. Flow cytometry showed that 3.8% of the largest and most complex cells of newly obtained larvae of H. contortus were positive for the GH receptor, and by immunofluorescence with confocal microscopy, it was observed that these receptors are located in the intestinal region larvae. In the in vivo assay, the administration of recombinant GH to gonadectomized lambs produced an increase in FEC (p<0.03), the number of female adult worms in the abomasum (p<0.05) and the levels of specific antibodies (p<0.04) in relation to the control lambs; however, it did not affect the fertility of H. contortus females. Although many factors affect the development and implantation of H. contortus in the abomasum of sheep, the results of this study strongly suggest that GH participates in the development and establishment of the parasite in sheep, mainly in young sheep.

Association of β-globin polymorphisms and tolerance to haemonchosis in ewes and lambs of different sheep breeds

Gastrointestinal nematodes (GIN), especially Haemonchus contortus, represent a significant challenge for sheep production. Given the global concern about GIN anthelmintic resistance, alternative control methods able to reduce the dependence on these drugs are highly advisable. Since previous studies have shown that sheep carrying the Hb-A allele of β-globin are more resistant to H. contortus, this study aimed to investigate the relationship between the different haplotypes (Hb-AA, Hb-AB and Hb-BB) and phenotypes in Santa Inês (SI), Texel (TX) and White Dorper (DO) breeds infected with H. contortus. Blood samples were collected from 180 ewes and 123 lambs of the three breeds for DNA extraction followed by qPCR using a hydrolysis probe to identify the β-globin haplotypes. Phenotypic data, including fecal egg count (FEC), packed cell volume (PCV), FAMACHA score and body condition score for ewes and lambs, as well as weight gain for lambs, were collected. The genotypic frequencies of β-globin for ewes and lambs were, respectively: 21.7% and 21.4% Hb-AA, 50% and 50% Hb-AB and 28.3% and 28.6% Hb-BB in SI; 0% and 0% Hb-AA, 18.6% and 9.4% Hb-AB and 81.4% and 90.6% Hb-BB in TX; and 0% and 0% Hb-AA, 13.1% and 0% Hb-AB and 86.9% and 100% Hb-BB in DO. In ewes, mean PCV differed (p<0.05) between the three haplotypes, with higher PCV in Hb-AA animals, followed by Hb-AB and Hb-BB. When considering each breed separately, SI Hb-AA ewes presented higher PCV (p<0.05), highlighting that even in a breed already considered resistant, animals with Hb-AA haplotype showed superior performance. Lambs with the Hb-AA haplotype exhibited a higher (p<0.05) mean PCV compared to those with Hb-AB and Hb-BB. The same pattern was found in SI when analyzing each breed separately. No significant association was found between β-globin haplotypes and FEC, FAMACHA score, body condition score, or weight gain. Nevertheless, given that anemia is the major clinical sign of haemonchosis, our findings on PCV reinforce that sheep carrying the Hb-A allele of β-globin are more tolerant to haemonchosis. This study may support the development of a valuable tool, targeting genetic selection for GIN control, reducing the dependence on anthelmintics and boosting sheep production worldwide.

Anthelmintic efficacy of an organic fraction from Guazuma ulmifolia leaves and evaluation of reactive oxidative stress on Haemonchus contortus

This study describes the anthelmintic efficacy of an organic fraction (EtOAc-F) from Guazuma ulmifolia leaves and the evaluation of its reactive oxidative stress on Haemonchus contortus. The first step was to assess the anthelmintic effect of EtOAc-F at 0.0, 3.5, 7.0 and 14 mg kg of body weight (BW) in gerbil's (Meriones unguiculatus) artificially infected with H. contortus infective larvae (L3). The second step was to evaluate the preliminary toxicity after oral administration of the EtOAc-F in gerbils. Finally, the third step was to determine the relative expression of biomarkers such as glutathione (GPx), catalase (CAT), and superoxide dismutase (SOD) against H. contortus L3 post-exposition to EtOAc-F. Additionally, the less-polar compounds of EtOAc-F were identified by gas mass spectrophotometry (GC-MS). The highest anthelmintic efficacy (97.34%) of the organic fraction was found in the gerbils treated with the 14 mg/kg of BW. Histopathological analysis did not reveal changes in tissues. The relative expression reflects overexpression of GPx (p<0.05, fold change: 14.35) and over expression of SOD (p≤0.05, fold change: 0.18) in H. contortus L3 exposed to 97.44 mg/mL of EtOAc-F compared with negative control. The GC-MS analysis revealed the presence of 4-hydroxybenzaldehyde (1), leucoanthocyanidin derivative (2), coniferyl alcohol (3), ferulic acid methyl ester acetate (4), 2,3,4-trimethoxycinnamic acid (5) and epiyangambin (6) as major compounds. According to these results, the EtOAc-F from G. ulmifolia leaves exhibit anthelmintic effect and increased the stress biomarkers on H. contortus.

Potential distribution modelling for Haemonchus contortus (Nematoda: Trichostrongylidae) in South America

The species Haemonchus contortus occurs in many regions worldwide, mainly parasitising small ruminants and economically impacting animal production. Climate change is considered a driving force for the risk of diseases caused by helminths and can also affect relationships between parasites and their hosts, with the potential to cause losses in both animal production and biodiversity in general. The aim of this study was to model the potential distribution of H. contortus in South America. We used MaxEnt to perform the analyses and describe the contribution of important bioclimatic variables involved in the species distribution. Our results show that H. contortus colonised most of the areas with habitats that suit the species' environmental requirements and that this parasite presents habitat suitability in a future scenario. Understanding the effects of climate change on the occurrence and distribution of parasite species is essential for monitoring these pathogens, in addition to predicting the areas that tend to present future parasite outbreaks and identify opportunities to mitigate the impacts of the emergence of diseases caused by these organisms.