Vitiello, P. | Search bioRxiv

bioRxiv2026

Evaluation of ivermectin effectiveness under contrasting anthelmintic resistance scenarios in beef cattle: a comparative study in Italy and Argentina

Beef cattle farming plays a crucial role in the livestock-related economies of both Italy and Argentina. Although both countries have grazing systems of meat production, the heterogeneity of those systems leads to different parasitological scenarios regarding epidemiology and the presence of resistance to commonly used anthelmintic drugs. Considering ivermectin (IVM) is the most widely used anthelmintic for treating gastrointestinal nematode (GIN) infections in cattle, the current studies evaluated the efficacy of ivermectin (IVM) given subcutaneously (SC) to both young calves and adult cows in ten (10) commercial cattle farms from Italy (A to E) and Argentina (F to J). The work was complemented with the assessment of the IVM plasma exposure and disposition kinetics both in young and adult animals. While adult cows and young calves were included in the study performed in Italy (Campania region), only calves aged 8-14 months old were selected to perform the efficacy trials in Argentina (central area of the Buenos Aires province). Fifteen (15) calves/cows naturally infected with GINs were treated with IVM (0.2 mg/kg) in each of the Farms. The therapeutic response (efficacy) was determined at 14 days after treatment by the faecal egg count reduction test. Six (6) adult cows and eight (8) young calves treated with IVM were randomly selected to perform the pharmacokinetic (PK) study with blood samples being taken 2 h and 21 days post-treatment. Drug concentrations were measured by HPLC. Similar IVM PK trends were obtained for both adult and young cattle. The IVM systemic exposure (expressed as AUC) obtained for adult cattle (380{+/-}158 ng.d/mL) was similar to that observed in calves group (313{+/-}85.5 ng.d/mL). No statistical differences between animals from both ages were observed for the most representative PK parameters (P>0.05). Surprisingly, while in Argentina IVM resistance was present in all the farms evaluated (90% CI = 0%-95%), in Italy a fully susceptible nematode population was presented in three farms (90% CI = 96%-100%) and only a very low level of IVM resistance was detected in the rest of the farms (90% CI = 92%-98%). Whereas Cooperia spp. and Haemonchus spp. were identified as the principal genera exhibiting resistance to IVM in Argentina, Cooperia spp., Ostertagia spp., and Oesophagostomum spp. were reported to display low levels of resistance under the Italian field scenario. In conclusion, IVM can be safely and effectively used in both young and adult cattle with similar disposition kinetic patterns. While its therapeutic response is failing under the conditions investigated in the Argentinian farms, its efficacy remains notably high in the Italian region under study. However, the use of IVM, as well any other active antiparasitic principle, should always be preceded by a diagnostic assessment of the nematode populations resistance status.

pharmacology and toxicology↗

bioRxiv2024

Identification of Thioredoxin1 interacting proteins in neuronal cytoskeletal organization during autophagy

Thioredoxin1 (Trx1) is a major cytoplasmic thiol oxidoreductase protein involved in redox signaling. This function is rendered by a rapid electron transfer reaction during which Trx1 reduces its substrate and itself becomes oxidized. In this reaction, Trx1 forms a transient disulfide bond with the substrate which is unstable and therefore identification of Trx1 substrates is technically challenging. This process maintains the cellular proteins in a balanced redox state and ensures cellular homeostasis. Trx1 levels are reduced in some neurodegenerative diseases; therefore, understanding the interactions between Trx1 and its substrates in neurons could have significant therapeutic implications. We utilized a transgenic mouse model expressing a Flag-tagged mutant form of Trx1 that can form stable disulfide bonds with its substrates allowing identification of the Trx1 interacting proteins. The involvement of Trx1 has been suggested in autophagy, we aimed to investigate Trx1 substrate after pharmacologic induction of autophagy in primary hippocampal neurons. Treatment of primary neurons by rapamycin, a standard autophagy inducer, caused significant reduction of neurite outgrowth and alterations in the cytoskeleton. Through immunoprecipitation and mass spectrometry, we have identified 77 Trx1 interacting proteins which were associated with a wide range of cellular functions including a major impact on cytoskeletal organization. The results were confirmed in Trx1 knocked-down cells and in nucleofected primary neurons. Our study suggests a novel role for Trx1 in regulation of neuronal cytoskeleton organization, marking the first investigation of Trx1-interacting proteins in primary neurons and confirming the multifaceted role of Trx1 in physiological and pathological states.

biochemistry↗