Purification of defective interfering T particles of vesicular stomatitis and rabies viruses generated in vivo in brains of newborn mice

Abstract

In contrast to adult mice, newborn mice generate defective interfering T particles after two high-multiplicity passages of cloned VSV B virions inoculated intracerebrally. After three or four serial intracerebral passages massive production of T particles was observed, and milligram quantities of B virions and T particles were purified directly from the brains of several litters of newborns. These purified brain T particles were shown to interfere strongly with B virions in vitro, to replicate true in vivo and in vitro, to contain small discrete subgenomic fragments of viral RNA, and to lack the ability to transcribe full-size viral messenger RNA molecules in in vitro transcriptase reactions. Rabies B virions generate large amounts of T particles during first passage in newborn mouse brains. It is concluded that defective interfering particles are not an artifact of in vitro and in ovo conditions and that at least some cells of mammals can generate and replicate, in vivo, significant yields of deletion mutants of RNA viruses. These particles meet criteria as being defective interfering particles similar to those produced in cell culture.