IFNA1 and infection: Interestingly, the virus that emerged on day 5 was unable to trigger detectable IFN responses (Fig 2C and 2D), agreeing with long standing evidence of intercalating “waves” of full-length and defective viral genomes during infection [37] (i.e. too many defective genomes interfere with viral replication reducing the full-length virus to almost negligible levels which, in turn, eliminates defective genomes that cannot replicate in the absence of viral proteins and allow the standard virus to re-emerge).