Immunoprecipitation of viral polypeptides of equid herpesvirus 1 and 4 by serum from experimentally infected ponies.

This research examines the reaction of ponies’ immune system after being infected with Equid Herpesvirus 1 or 4 (EHV-1 or EHV-4), aiming to identify the viral proteins which triggered measurable immune responses.

Objective of the Research

• The study’s primary aim was to understand which viral polypeptides (VPs) from Equid Herpesvirus 1 and 4 were detected and targeted by the infected ponies’ immune system. The researchers used serums extracted from two sibling groups of ponies infected with EHV-1 and EHV-4.

Methodology

• The research team conducted Immunoprecipitation, a process that involves the precipitation of a protein antigen (in this case, the viral proteins) out of solution using an antibody that specifically binds to that particular protein; the precipitated proteins were then labelled with 35S-Methionine or 3H Glucosamine.
• The selection of the specific viral proteins targeted was determined based on which proteins offered maximum precipitation.

Key Findings

• The research reported recognition and subsequent immune response in the ponies as soon as 8 days post-infection.
• Several specifically labelled polypeptides of EHV-1 were immunoprecipitated by sera from both groups, with molecular weights (Mr) varying within a particular range.
• Of these polypeptides, those with a weight of 148kDa gave the maximum precipitation, indicating their significant antigenic property.
• It was also discovered that two polypeptides with weights of 117 and 77-79 kDa were the gB homologue of Herpes simplex virus – also showing intensive precipitation, pointing out these as significant antigenic proteins in the infection process.
• For EHV-4, the homologous viral proteins precipitated were similar to those of EHV-1, but there were also distinctive differences, including absence of bands at 123 and 70 kDa, and two faint bands of Mr 60 and 55 kDa instead of the precipitated VP55K of EHV-1.
• High molecular weight polypeptides (greater than 200 kDa) were not frequently seen and seemed less significant in both viruses.

Conclusion

• The study thus concludes that the major nucleocapsid protein of 148kDa and the gB analogues of 117 and 77kDa were the most antigenic in experimental infections of ponies with either EHV-1 or 4. These exhibited reciprocal precipitation, suggesting the ponies’ immune system’s direct response to these viral proteins in both types of Equid Herpesvirus infections.