Persistent infection with infectious pancreatic necrosis virus mediated by defective-interfering (DI) virus particles in a cell line showing strong interference but little DI replication

The characteristics of chinook salmon embryo cells persistently infected with infectious pancreatic necrosis virus were consistent with defective-interfering (DI) particle-mediated persistence. All the cells were infected and were slowly releasing virus, but they could be cured of virus in the presence of antiserum. Immunofluorescence showed that the amount of virus antigen in persistently infected cells was low. This fact, coupled with the observation that few DI particles were released by these cells, indicated that DI particles were not replicated to excess in this cell line.