A study of the interference phenomenon in vesicular stomatitis virus replication

Summary

Baby hamster kidney cell monolayers were infected with unfractionated vesicular stomatitis virus at input multiplicities ranging from 1 to 1/10⁵. Cells infected at multiplicities of 1/10³ or less produced 10 times as much infective virus but considerably less interfering component than cells infected at multiplicities exceeding 1/100. This has been shown to be due to the presence in the unfractionated virus pool of 2 viruses having different growth rates. The faster growing virus (lag phase 2 hours) does not cause interference, even at multiplicities greater than 100, and does not produce measurable amounts of interfering component in a single passage. The slower growing virus has a lag phase of 3.5 hours and produces large quantities of interfering component in addition to infective virus. This virus will also interfere with viral replication when 10 to 50 particles are added to each cell. A similar number of interfering particles are required to produce the same amount of inhibition. The interfering particle is not self-replicating but is produced only when virus multiplies. The simultaneous presence of infective and interfering particles in a virus harvest is explained by the earlier formation and release of infective virus in the growth cycle.