Effect of SGIV VP51 overexpression on virus replication. (a) Virus production of SGIV infected VP51 overexpressing cells. Stable FHM cells infected with SGIV at different time points (0, 6, 24, 36 and 48 h p.i., respectively) were collected, and the viral titres were determined using the TCID50 method. (b) Relative mRNA levels of SGIV ICP-18, MCP and LITAF in different stable FHM lines after SGIV infection at 48 h p.i. were assessed by a qPCR assay. n = 3; error bars represent the mean ± sd; *P < 0.05 compared with FHM cells expressing VP51 (FHM-VP51).