Mapping epitopes in equine rhinitis A virus VP1 recognized by antibodies elicited in response to infection of the natural host.

The research study focuses on identifying the linear B cell epitopes in the VP1 capsid protein of Equine Rhinitis A Virus (ERAV), which have an important role in inducing an immune response. The research was conducted using sera from ERAV-infected horses and polyclonal sera from ERAV-immunized rabbits and mice and found significant B cell epitopes located in different regions of the ERAV VP1 capsid protein.

Objectives of the Research

• The main objective of the research was to locate linear B cell epitopes in the VP1 capsid protein of ERAV. Identifying these regions is crucial in understanding the immunogenic properties of ERAV and could potentially contribute to effective vaccine development.

Methods Used

• The researchers utilized a method of expressing overlapping fragments of the ERAV VP1 protein in Escherichia coli as glutathione S-transferase (GST) fusion proteins. This cutting-edge method allows for an easier identification of the specific reactive regions of the protein.
• These GST fusion proteins were then tested for reactivity with sera from ERAV-infected horses and polyclonal sera from ERAV-immunized rabbits and mice. This step tested the immune response of these animals to the ERAV VP1 protein components.

Findings of the Research

• The research led to the identification of areas on the N- and C-termini, as well as the betaE-betaF and betaG-betaH loop regions of the ERAV VP1 protein, which contained B cell epitopes. These epitopes are regions of the protein that are recognized by B cells, leading to an immune response.
• It was also discovered that GST fusion proteins of these regions triggered the production of antibodies in rabbits and mice when used as immunization. These antibodies generally strongly recognized the native ERAV VP1 protein, indicating that they are productive immune responses. However, they were non-neutralizing, meaning they didn’t inhibit the function of the virus.

Conclusion

• The study concluded that the N-terminal region of the ERAV VP1 protein, in particular, contains strong B cell epitopes. This indicates that this region is crucial in igniting the immune response effectively against the virus and forms the basis of further study for vaccine development.