Evaluation of Directigen Flu A assay for detection of influenza antigen in nasal secretions of horses.

This research investigated the effectiveness of the Directigen Flu A assay in detecting influenza virus in horses. It found that the test was more sensitive than traditional methods, successfully identifying the virus in between 33% and 45% of diseased horses during influenza outbreaks, compared to a 7% detection rate with conventional techniques.

Study Purpose and Method

• This study set out to evaluate the efficacy of the Directigen Flu A assay, a readily available immunoassay, for detecting influenza A nucleoprotein in horses.
• The study specifically addressed its use in identifying the virus in nasal secretions of horses naturally infected with the virus.

Study Findings

• The Directigen Flu A assay reacted with types of influenza virus known to inflict horses with disease, but it didn’t react with secretions from uninfected horses kept separate from the others.
• Between 33% and 45% of nasal secretion samples from horses showing signs of disease during influenza outbreaks responded positively to the assay. This shows a significant level of effectiveness in disease detection.
• On the flip side, the assay ruled out influenza infection in 95% to 98% of horses not showing signs of the disease during flu outbreaks. This suggests high specificity of the test, minimizing false-positive results.

Comparison with Traditional Techniques

• The assay’s performance was compared to conventional techniques used to isolate the influenza virus; the traditional methods detected the virus in only 7% of diseased horses. This outcome underlines the higher sensitivity of the Directigen Flu A assay relative to traditional screening methods.

Correlation with Clinical Symptoms and Pre-Exposure Antibody Levels

• Diseased horses that tested positive in the Directigen assay demonstrated more clinical symptoms and had lower pre-exposure influenza antibody concentrations than horses that tested negative. This highlighted an association between severity of clinical manifestations, antibody levels, and detection results of the assay.

Conclusion

• Overall, the research concluded that the Directigen Flu A assay significantly improves the detection of influenza virus in horses’ nasal secretions, outperforming conventional virus isolation techniques with its greater sensitivity.