IFNA1 and infection: Furthermore, despite similarity in expression levels in the acute phase of infection, the absence of hyperactivated IFN expression is a distinctive factor between pathogenic and non-pathogenic forms of SIV; while pathogenic SIVmac in rhesus macaques features an elevated IFN signature and resultant disease and the non-pathogenic SIVagm and SIVsmm in African green monkeys and Sootey mangabeys, respectively, neither exhibit aberrant IFN upregulation nor immune activation (92–94).