Identification of a major immunogenic region of equine herpesvirus-1 glycoprotein E and its application to enzyme-linked immunosorbent assay.

The study identified a key immune-triggering area on the glycoprotein E (gE) of equine herpesvirus-1 (EHV-1). It also described the development of an enzyme-linked immunosorbent assay (ELISA) which uses synthetic peptides to distinguish between EHV-1 and EHV-4 infections. This ELISA method could potentially be used as a vaccine marker when a modified live EHV-1 virus lacking the gE gene is introduced.

Understanding the Research

• The research primarily focuses on identifying the main immunogenic region (a part which triggers the immune response) of a protein called glycoprotein E (gE) in equine herpesvirus-1 (EHV-1). This was initially tested by splitting the gE into fragments and expressing them as fusion proteins in a bacterium (E. coli).
• These proteins were then analysed for their ability to trigger an immune response in horses that had been experimentally infected with EHV-1. A specific sequence of 33 amino acids in gE was identified that interacted with antibodies induced by infection with EHV-1, providing a basis for the main immunogenic region on the virus.

Developing the ELISA

• The researchers then compared the antigenicity of three certain regions of the gE protein using the enzyme-linked immunosorbent assay (ELISA). ELISA is a technique used to detect and measure antibodies in blood, and is based on antibodies binding specifically to antigens.
• One of these regions, denoted as gE1(169-188), was found to contain a major B-cell epitope. B-cell epitopes are the sites on the antigen recognised by B-cells, a type of immune cell that produces antibodies.
• An ELISA technique was developed using two synthetic peptides corresponding to the major immune-triggering regions of EHV-1 and EHV-4 respectively. This test was able to differentiate between infections of EHV-1 and EHV-4.

Significance and Further Applications

• This research also holds significance as a live vaccine for EHV-1 that lacks the gE gene is expected to be introduced in Japan. The antibodies formed against this vaccine wouldn’t interact with the ELISA test in question, as it targets a major part of the gE protein.
• This means that the developed ELISA test can be used to differentiate between horses that have been infected with EHV-1 and those that have been inoculated with the modified live EHV-1 vaccine (EHV-1 ΔgE).
• Therefore, the novel ELISA method developed can serve as a simple and effective tool to distinguish between EHV-1 and EHV-4 infections, as well as potentially being a marker for the EHV-1 ΔgE vaccination, once it is rolled out.