In vitro efficacies of oseltamivir carboxylate and zanamivir against equine influenza A viruses.

The research study investigates the effectiveness of two NA inhibitors, oseltamivir carboxylate and zanamivir, against equine influenza A viruses in a laboratory setting. The results suggest that these inhibitors are successful in hindering most strains of the virus, advocating their potential use in treating horses affected by the influenza A infection.

Objective of the Research

• The primary aim of the study was to evaluate the potential use of two NA inhibitors – oseltamivir carboxylate (OC) and zanamivir (ZA) – as treatment agents for equine influenza A virus (EIV) infection. This virus is a common pathogen affecting horses, therefore finding effective treatment strategies is important for the wellbeing of these animals.

Research Methodology

• The researchers investigated the efficacy of OC and ZA against twelve lab-grown EIVs. The efficacy was determined by measuring the ability of the inhibitors to restrict the NA activities and plaque formation of the virus in MDCK (Madin-Darby Canine Kidney) cells. MDCK cells are a type of epithelial cell line often used in laboratory research.
• These inhibitory actions were quantified by recording the 50% inhibitory concentrations (IC50), which refers to the concentration of a substance required to inhibit a specific biological or biochemical function by half. Lower IC50 values indicate greater effectiveness of the inhibitors.

Results and Findings

• The NA activities of all tested EIVs were effectively inhibited by both OC and ZA, with IC50 values ranging from 0.017 to 0.130 microM, and 0.010 to 0.074 microM, respectively.
• In terms of plaque forming, OC and ZA were successful in restricting all EIVs in the MDCK cells, except for one strain. The IC50 values for this inhibitory action ranged from 0.015 to 0.097 microM for OC and from 0.016 to 0.089 microM for ZA. However, notably higher values (13.328 microM and 6.729 microM) were recorded for the single strain that resisted the inhibitory actions.

Conclusion

• The results from the in vitro study demonstrate that the NA inhibitors OC and ZA can effectively control the NA activity and plaque formation of most EIVs. Given these findings, the researchers suggest these inhibitors have potential application as clinical agents for treating equine influenza A infection in horses.