HIF1A and viral infectious disease: When the O2 level is normal, bacterial or viral infections can upregulate HIF-1α mRNA and protein levels.23, 24, 25, 26, 42 Interestingly, we found that H1N1 infection did not alter HIF-1α mRNA or total protein expression, but it did induce nuclear translocation of HIF-1α under normal oxygen concentrations.