mRNA expression measured at various time points (1, 3, 12, 24, 36 and 48 hpi) by real-time RT-PCR showed that infection of PK-15 cells with CSFV at either a MOI of 0.1 or 1.0, resulted in down-regulation of seven immune response genes, namely SLA-2, TAP1, SLA-DR, Ii, CD40, CD80, CD86. This evidence concerns the gene CD40 and infection.