Identification of linear B cell epitope on gB, gC, and gE proteins of porcine pseudorabies virus using monoclonal antibodies

Since 2011, there have been outbreaks of pseudorabies (PR) in several pig farms despite vaccination coverage, which causes substantial economic loss to the swine industry in China. The emergence of a pseudorabies virusvariant strain with high virulence and antigenic variation (e.g., PRV ZJ01), is considered to be the primary cause. In this study, truncated gB, gC, and gE of PRV ZJ01 was expressed and used to generate seven monoclonal antibodies (mAbs) against gB, gC, or gE. An indirect immunofluorescence assay (IFA) revealed that these mAbs were specific against PRV. Subsequently we identified the B cell epitopes recognized by these mAbs by Western blot. The mAbs 5A2 and 6G5 against gB recognized the same B cell linear epitope at 576SAVATAA582, the mAb 5D10 against gC recognized the B cell linear epitope at 134GETFE138, mAb 7C5 against gC recognized the B cell linear epitope at 143RRGRFRSPDAD153, and mAbs 3E1, 3H8, and 4D2 against gE recognized the same B cell linear epitope at 151IGDYL155 of gE. Biological information analysis showed that these B cell linear epitopes are highly conserved among different PRV isolates and the epitope 143RRGRFRSPDAD153 with a high antigenic index and high hydrophilicity, fully exposed on the surface of the gC, is likely to be an important B cell epitope. These mAbs and their defined epitopes may provide useful tools for the study of the structure and function of the PRV protein, analysis of antigenic epitope characteristics, and establishment of antibody detection methods.