Monoclonal antibodies reactive with the surface and secreted glycoproteins of Marek's disease virus and herpesvirus of turkeys.

Hybridomas were formed between mouse myeloma cells and spleen cells from mice immunized with Marek's disease virus (MDV) or with herpesvirus of turkeys (HVT). Three monoclonal antibodies were obtained, two (M26 and M34) from MDV clones and one (H9) from an HVT clone, all of which were specific for cross-reactive membrane antigen (MA) expressed on the surface of cells infected with MDV or HVT. All three antibodies also reacted with MDV- and HVT-specific glycoproteins in the molecular weight (mol. wt.) ranges 54K to 70K (MDV-gp54/70) and 50K to 64K (HVT-gp50/64), respectively. These glycoproteins constitute the putative 'A' antigens which are found in the medium of cultures infected with MDV or HVT. These results suggest that the cross-reactive MA may correspond to 'A' antigen. Pulse-chase experiments using monoclonal antibodies revealed the presence in virus-infected cells of precursor and processed forms of MDV-gp54/70 and HVT-gp50/64 which differ in size. Moreover, by two-dimensional gel electrophoresis we found that MDV and HVT glycoproteins were separated to heterogeneous spots by electric charge as well as mol. wt. The several spots with higher mol. wt. and with more acidic isoelectric points among them were lost by treatment with neuraminidase, suggesting that the processing was, at least in part, due to the addition of sialic acid to the precursor forms. Tunicamycin blocked the surface expression of cross-reactive HVT-MA on HVT-infected cells. Phosphonoacetic acid inhibited both the appearance of HVT-MA on the cell surface and synthesis of HVT-gp50/64, indicating that the MA and secreted glycoprotein were late gene products of the HVT genome.