NR1H4 and hepatitis A virus infection: Following histopathologic evaluation of livers, mean hepatitis index (HI) was significantly elevated in infected FXR KO mice (1.63±2.25, mean ± SD) when compared to sham-treated WT mice (0.083±0.192, P<0.01), characterized by prominent portal inflammatory aggregates (chiefly B and T cells) and mild lobular inflammation (lymphocytes and macrophages) (Fig. 2A).