title: Quantitative analysis of defective interfering particles in infectious pancreatic necrosis virus preparations.
abstract: Infectious pancreatic necrosis virus exhibited an interference phenomenon that resulted in the survival of the infected cell with one hit kinetics. The responsible factor was found to co-purify with standard virus through a purification regime that employed two CsCl gradients and a sucrose gradient. This result suggested that a defective interfering (DI) viral particle was involved. It was possible to estimate the number of DI particles by a statistical method using the Poisson distribution that related cell survival to input DI/cell, which indicated that virus samples from dilute passage contained as many DI particles as samples from undiluted passage; this means that multiple undiluted virus passage did not increase the yield of DI particles. In isopycnic CsCl gradient centrifugation, the DI particles were found in a broad band superimposed over the standard virus peak and extending above it, such that the ratio DI/PFU varied from 0.3--20 in different fractions. These centrifugation methods did not completely separate DI particles from standard virus.
mesh_terms: D000818:Animals; D002460:Cell Line; D002499:Centrifugation, Density Gradient; D003673:Defective Viruses / Q000254:growth & development / Q000302:isolation & purification*; D012087:Reoviridae / Q000254:growth & development / Q000302:isolation & purification*; D012487:Salmonidae; D014762:Viral Interference; D014779:Virus Replication