Addition of exogenous prostaglandin E2 can compensate for COX-induced inhibition of feline calicivirus (FCV) and murine norovirus (MNV) replications.

(A–D) CRFK cells and RAW264.7 were infected with FCV (MOI, 1 FFU/ml) and MNV (MOI, 1 TCID₅₀/ml), respectively, and then treated with noncytotoxic doses of indomethacin and NS-398 for MNV and FCV, respectively. Two doses of exogenous PGE₂, 5 or 50 μM for MNV, and 2 μM or 20 μM for FCV, were then added in the maintenance media, and samples were harvested at 8 h post-infection (hpi) for FCV and 24 hpi for MNV. Viral titer and viral genome copy numbers were determined by TCID₅₀ and quantitative real time PCR analyses and compared between mock- and drug-treated groups. The data presented are means and standard errors of the mean from three different experiments. Statistical analysis was performed using one-way analysis of variance. ** p < 0.001.