Search

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 (L 3 ) and adults. Furthermore, we exposed H. contortus transitional infective larvae (xL 3 ) to erythrocytes or hydrogen peroxide (H 2 O 2 ) 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. xL 3 exposed to erythrocytes or H 2 O 2 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., Competing Interests: Declaration of Competing Interest We also state that there is no conflict of interest associated with this second manuscript version and there is not financial or personal relationship with other people or organization that could inappropriately influence our work., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study assessed the immunoprotective effect in lambs of a native excreted/secreted 15-kDa protein and two synthesised S28 peptides derived from the infective transitory larvae (xL 3 ) and adult stages (AS) of Haemonchus contortus . Twenty-two Pelibuey lambs were divided into negative and positive control groups, as well as immunised lamb groups, with 100 µg of the 15-kDa native protein (15kDaNP) and S28 peptides (S28P). The eggs per gram (EPG) and haematocrit were measured, and AS were counted and morphologically measured. To assess the immunoprotection in lambs, indirect enzyme-linked immunosorbent assays and relative expression analyses of immune cytokines were performed using serum and abomasal samples. Our results showed a 72.28% reduction in adult worms (AW) in the 15kDaNP-immunised group, achieving a high clinical response with 41% haematocrit and low EPG values (436 ± 661). Conversely, the S28P group achieved the highest IgG levels (2.125 ± 0.880 OD), with AW exhibiting the greatest body length ( p > 0.05) and upregulation of the IL5 and FCεR1A genes associated with nematode control. The 15kDaNP group showed increased expression of genes related to nematode control and anti-inflammatory responses, including IL4 , IL5 , IL6 , and IL13 ( p < 0.05). The S28P and 15kDaNP should be explored as potential vaccines against sheep haemonchosis.

The aim of the study was to compare the relative gene expression of Haemonchus contortus P-glycoprotein genes ( Hco-pgp ) between fourth (L 4 ), infective (L 3 ), and transitory infective (xL 3 ) larval stages as laboratory models to study ivermectin (IVM) resistance. The H. contortus resistant to IVM (IVMr) and susceptible to IVM (IVMs) strains were used to develop xL 3 in vitro culture and to infect Meriones unguiculatus (gerbils) to collect L 4 stages. Morphometric differences were evaluated from 25 individuals of H. contortus from each strain. Relative gene expression from xL 3 and L 4 was determined between comparison of IVMr stages and from IVMr vs IVMs stages. Seven Hco-pgp genes (1, 2, 3, 4, 9, 10, and 16) were analysed by RT-qPCR using L 3 stage as control group, per strain, and GAPDH and β-tubulin as constitutive genes. Morphological changes were confirmed between xL 3 and L 4 developing oral shape, oesophagus, and intestinal tube. In addition, the body length and width showed statistical differences ( p < 0.05). The Hco-pgp 1, 2, 3, and 4 genes ( p < 0.05) were upregulated from 7.1- to 463.82-fold changes between IVMr stages, and Hco-pgp9 (13.12-fold) and Hco-pgp10 (13.56-fold) genes showed differences between L 4 and xL 3 , respectively. The comparative study between IVMr vs IVMs strains associated to xL 3 and L 4 displayed significant upregulation for most of the Hco-pgp genes among 4.89-188.71 fold-change. In conclusion, these results suggest the use of H. contortus xL 3 and L 4 as suitable laboratory models to study IVMr associated with Hco-pgp genes to contribute to the understanding of anthelmintic resistance.