Whereas the level of Tmprss4 transcripts was not significantly higher in DBA/2J compared to C57Bl/6J mice before infection (1.7 fold) and at day 1 p.i. (3.7 fold), comparable levels were recorded in both mouse strains at day 3 p.i. After day 3, the transcript level was significantly up-regulated in C57Bl/6J compared to DBA/2J. This evidence concerns the gene TMPRSS4 and infection.