Fjernelsen af gE genet muliggør differentiering mellem dyr vaccineret med gE- negative vacciner (anti gE antistof negative, IBR vironeutraliserende antistof positive) og naturligt inficerede dyr (positive over for både IBR vironeutraliserende antistof og anti gE antistof).
The gE gene deletion allows differentiation between animals vaccinated with gE-negative vaccines (anti gE antibody negative, IBR vironeutralising antibody positive) and naturally infected animals (positive to both IBR vironeutralising antibody and anti gE antibody).