Differentiated macrophage cultures were pre-treated with 1 U/ml or 10 U/ml recombinant mouse TNFα (Endogen, PIERCE; 10 μg/ml corresponded to 105 U/ml) for 24 h prior to infection and viral replication monitored by plaque assay at day 3 p.i. As expected Figure 10A shows that pre-treatment with TNFα in vitro reduces viral titres of MCMV. Here, TNF is linked to infection.