Equine herpesvirus 1 glycoprotein D expressed in E. coli provides partial protection against equine herpesvirus infection in mice and elicits virus-neutralizing antibodies in the horse.

The research investigates the potential of a certain glycoprotein, specific to Equine Herpesvirus 1 (EHV-1), to act as a vaccine against the virus when produced in E. coli bacteria. The results suggest that E. coli could be a functional and efficient tool for mass-producing this vaccine.

About Equine Herpesvirus 1 and glycoprotein D

• Equine Herpesvirus 1 (EHV-1) is a virus that infects horses, and its envelope glycoprotein D (gD) plays an important role in the infection process.
• This glycoprotein is required for the virus to infect host cells and it triggers a notable response from the host’s immune system, making it a potential candidate for a vaccine.

The study’s methodology

• In this study, a truncated form of EHV-1 gD (gDt) was engineered with a C-terminal hexahistidine tag and produced in E. coli bacteria using a pET vector.
• Western blot analysis was conducted to verify the presence of this structurally modified glycoprotein.
• The immune response incited by this artificially produced glycoprotein was compared to that from gD expressed in insect cells.
• The gDt protein was administered to mice in a BALB/c mouse model of EHV-1 respiratory infection to assess its vaccine-like capabilities.
• A prime-boost protocol was also used following an initial inoculation with gD DNA to see the effect of repeated exposure.

The research results

• The researchers discovered that the artificial gDt induced similar levels of gD-specific antibody and neutralizing antibody compared to Bac gD (the variant found in insect cells).
• The produced protein also provided comparable levels of protection against EHV-1 challenge in mice.
• Upon inoculation in horses, gDt elicited EHV-1 gD-specific antibodies and virus-neutralizing antibodies.

The study’s implications

• The results suggest that despite the lack of glycosylation, a process typically important in immune reactions, E. coli may serve as an effective means to produce gD on a large scale for vaccine tests.
• If gDt produced in E. coli could reliably protect against EHV-1, it would present a more cost-effective and easily scalable method for mass vaccine production.