High-load PRV infection did produce an interferon response, increasing mean ISG expression by approximately tenfold at peak infection (4 wpc) as measured by the equal-weighted mean of mx1, rsad2, and eif2ak2 mRNA transcripts which code for three prominent interferon-stimulated proteins: Myxovirus resistance (Mx1), Viperin, and RNA-activated protein kinase (PKR), respectively (Fig. 1c). The gene discussed is MX1; the disease is infection.