The outbreak of equine influenza (H3N8) in the United Kingdom in 1989: diagnostic use of an antigen capture ELISA.

This research discusses the incidence of equine influenza in the UK in 1989, despite vaccination, and the use of an antigen-capture ELISA test as a rapid detection method for the virus in horses.

Background of the Research

• The study was sparked in July 1989 when a non-thoroughbred horse showed acute signs of respiratory disease, following which a nasopharyngeal swab of the horse was collected and tested.
• Upon testing, the horse was found to be infected with influenza A/equine-2 (H3N8) making this the first isolation of equine influenza virus in the UK after a period of eight years, i.e., since 1981.
• This sparked an interest in further investigation of acute respiratory diseases in horses, and it was seen that the infection was actually widespread all over the UK.

Uniqueness of the 1989 Outbreak

• Contrary to the equine influenza outbreak in the UK in 1979, the horses infected in the 1989 outbreak were already vaccinated against the influenza virus.
• This was unusual, and an important aspect of the research, because effectively vaccinated horses should essentially not contract the disease, signifying that there may have had been a mutation in the equine influenza virus or there were lapses in the vaccination procedure, coverage, or immunity granted by the vaccine.

Use of Antigen Capture ELISA in Diagnostics

• This unexpected outbreak provided an opportunity to implement and evaluate an antigen capture ELISA, a rapid method for detecting the influenza virus in horses.
• The ELISA, Enzyme-Linked Immunosorbent Assay, is a test that detects and measures antibodies in your blood. In this research, the test was used to identify the influenza virus by aiming it against the influenza virus nucleoprotein.
• By using this diagnostic method it was possible to rapidly detect the presence of the virus in the nasopharyngeal secretions of naturally infected horses.