The NS segment encodes two proteins via splicing, NS protein 1 (NS1) and nuclear export protein (NEP, also known as NS2).2 NS1 is one of the earliest proteins expressed during virus infection and has been well characterized as a potent type I interferon (IFN) antagonist.3 In contrast, NEP serves a nuclear export function and is expressed at a later stage during infection as a less abundant spliced product of the NS segment.4 While IAV with an NS1 deletion is replication competent, albeit attenuated,5 IAV lacking NEP is a replication-incompetent virus.6 The gene discussed is IFNA1; the disease is infection.