Virus-Cell Interactions Elizabeth B. Wignall-Fleming, Andri Vasou, Dan Young, John A.L. Short, David J. Hughes, Steve Goodbourn, Richard E. Randall DOI: 10.1128/JVI.00246-20 ABSTRACT During the replication of parainfluenza virus type 5 (PIV5) copyback defective virus genomes (DVGs) are erroneously produced and are packaged into “infectious” virus particles. Copyback DVGs are primary inducers of innate intracellular responses, including the interferon (IFN) response.