Ectromelia virus-induced changes in primary cultures of mouse hepatocytes

Mouse hepatocytes were isolated by collagenase perfusion, maintained in non-proliferating monolayer culture and shown to retain liver cell function as judged by gluconeogenesis for 15 to 18 h. Such cells could be infected with and support the replication of a virulent strain of ectromelia virus. Virus antigen and characteristic cytoplasmic 'B'-type poxvirus inclusion bodies were demonstrated by immunofluorescence in virtually all cells. By electron microscopy it was shown that 'B'-type inclusions were the site of virus replication, and that the biogenesis of ectromelia virus and ultrastructural changes in hepatocytes were similar to those observed in infected mouse livers. Early cell rounding effects, a normal characteristic of poxvirus infections in tissue culture cells, were not seen in ectromelia-infected hepatocytes, although late degenerative changes did occur. Pulse-labelling of hepatocyte cultures with [35S]methionine showed that ectromelia virus inhibited the rise in protein synthesis seen in controls and imposed a gradual decline in host protein synthesis to an extent and at a rate significantly different from that in mouse L929 cells. Gluconeogenesis was inhibited by ectromelia virus infection of hepatocytes.