NHC (EIDD-1931)

Nevertheless, it has certain limitations in clinical practice: drug resistance, disease relapse, and unsatisfactory efficacy against neurological manifestations are observed in some cases.Moreover, prolonged monotherapy readily induces resistant viral mutations. By contrast, NHC (EIDD-1931), with superior in vitro antiviral activity and a unique mutagenic mechanism, serves as a novel alternative therapeutic agent for FIP treatment, addressing the shortcomings of existing therapeutic protocols.Multiple in vitro controlled studies have verified that EIDD-1931 exerts markedly stronger inhibitory activity against FIPV than GS-441524. In vitro pharmacodynamic assays targeting Type II FIPV demonstrate that the half-maximal effective concentration (EC₅₀) of EIDD-1931 is as low as 0.11 μM, far lower than the corresponding value for GS-441524.

Livestock and Poultry Farming Sector: In Vitro Research on Prevention and Control of Livestock and Poultry RNA Viruses

RNA viral diseases of livestock and poultry represent core epidemic diseases restricting large-scale farming. Characterized by rapid transmission, high morbidity and frequent large-scale outbreaks, these diseases elevate animal mortality, impair production performance and inflict massive economic losses on the breeding industry. Vaccination remains the primary preventive strategy against livestock and poultry RNA viral diseases, whereas specific therapeutic drugs are scarce.

It mainly infects suckling piglets and induces severe vomiting, diarrhoea and dehydration; mortality among neonatal piglets can reach 100%. Conventional prevention and control strategies struggle to contain outbreaks caused by viral variant strains. In vitro cellular experiments reveal that EIDD-1931 efficiently suppresses PEDV proliferation in host cells, significantly lowering viral copy numbers and inhibiting cytopathic effects. Its mechanism of action covers the whole viral life cycle including adsorption, replication and assembly. It not only interferes with replication of the viral RNA genome but also reduces the release of progeny virions and blocks cell-to-cell viral transmission.

Avian coronavirus is represented by infectious bronchitis virus (IBV), which infects poultry of all ages and triggers respiratory inflammation, renal injury, reduced egg production and other complications.

Secondary bacterial infections commonly occur, substantially increasing poultry mortality. Existing preventive vaccines suffer from weak cross-protection and delayed updates, and effective therapeutic drugs are lacking in clinical settings. In vitro research data show that EIDD-1931 markedly inhibits IBV RNA replication, effectively alleviates virus-induced cellular damage and reduces viral invasiveness towards avian respiratory mucosal cells.

Such diseases feature abrupt onset, rapid spread and high mortality. Coupled with complex aquatic environments, epidemic prevention and control pose enormous challenges. Fish rhabdoviruses form the most destructive group of RNA viruses in aquaculture, encompassing multiple pathogenic strains such as grass carp haemorrhagic disease virus and spring viraemia of carp virus.

These viruses infect various freshwater farmed fish and trigger mass mortality, severely hindering high-quality development of the aquaculture industry. Currently, the supply of aquatic antiviral drugs is limited. Most available agents carry drawbacks including high toxicity, substantial residues and disruption of aquatic ecosystems. Safe and efficient novel antiviral pharmaceuticals are therefore urgently required.

In vitro cell culture experiments indicate that EIDD-1931 significantly reduces viral titres in rhabdovirus-infected cells and effectively suppresses cytopathy.

Within therapeutically effective antiviral concentrations, EIDD-1931 exhibits no obvious toxicity to primary fish cells and possesses favourable cellular compatibility.

NHC (EIDD-1931) presents outstanding advantages over traditional aquaculture antiviral drugs.

Third, it achieves high safety and low residue risks. As a small-molecule compound, EIDD-1931 undergoes rapid metabolism and does not accumulate heavily in aquatic organisms or disrupt aquatic microbial ecosystems, complying with the development principles of green aquaculture. At present, research on EIDD-1931 against aquatic animal RNA viruses mainly focuses on in vitro pharmacodynamic verification. Further investigations into in vivo efficacy, administration modalities and suitability for aquatic environments are required to lay a foundation for its large-scale application in aquatic disease prevention and control.