As detailed in Figure 2, key questions remain, however, including (1) what are the specific populations of bacteria present within the intestine and can these be correlated with or used as a screening tool for the progression of liver disease, (2) how do different microbiota populations influence gut barrier integrity, and (3) what are the cell-specific effects of gut-derived antigens within the injured liver (i.e., KC, stellate cell, T cell, endothelial cell, etc.)and does the type of injury influence their effects (i.e., ischemic damage versus viral infection). This evidence concerns the gene CALCA and viral infectious disease.