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

Sera from two sibling groups of ponies experimentally infected with Equid herpesvirus 1 or 4 (EHV-1 or 4) were used to investigate which viral polypeptides (VPs) of EHV-1 and EHV-4 were recognised. Recognition was detected as early as 8 d.p.i. and thereafter. The polypeptides of EHV-1 (labelled with 35S-methionine) immunoprecipitated (IIP) by sera from both groups had Mr of 148, 138, 123, 117, 110, 77-79, 70, 55, 49-50, 47, 40 and 35-37 kDa respectively. Of these VP148K (VP9 nucleocapsid) gave the maximum precipitation, followed by 117 and 77-79 kDa. The latter were confirmed by monoclonal antibodies as the gB homologue of Herpes-simplex virus (HSV). With EHV-4 the homologous VPs precipitated were similar to those of EHV-1. However, instead of the precipitated VP55K of EHV-1, there were two faint bands of Mr 60 and 55 kDa, neither of significant density. Bands at 123 and 70 kDa were absent. High MW polypeptides (>200 kDa) were not significant and infrequently seen with both viruses. Labelling EHV-1 with 3H glucosamine indicated that viral glycoproteins (VGPs) at an Mr of 79-88 kDa (equivalent to gB and gC) were most commonly recognised in homologous EHV-1 IIP and at 83 kDa (gC) in heterologous IIP. The EHV-4 immunoprecipitated VGPs were at 230-300 kDa with bands at 290 kDa and 250 kDa. Also detected were bands at 100, 123, 79-88, 58-61K and 54-55 kDa. The 79-88 kDa polypeptides gave maximum density and were considered as homologues of HSV gB and gC. Thus the overall profile indicated that following experimental infection the major nucleocapsid protein of 148K, and the gB analogues of 117 and 77 kDa were the most antigenic in experimental infections of ponies with either EHV-1 or 4 and that these showed reciprocal precipitation.