RESCUE OF MEASLES-VIRUS USING A REPLICATION-DEFICIENT VACCINIA-T7 VECTOR

A system which allows the reconstitution of measles virus (MV) from cl oned cDNA is described. The severely host cell restricted vaccinia vec tor MVA-T7 expressing bacteriophage T7 RNA polymerase was used to gene rate full-length antigenomic MV RNA and simultaneously the mRNAs encod ing the viral N, P and L proteins in order to produce replicationally and transcriptionally active nucleocapsids. The functionality of the N , P and L proteins was demonstrated first by their ability to rescue M V specific subgenomic RNAs. Assembly and budding of reconstituted MV w as shown by syncytia formation and subsequently by virus isolation. Th e inability of MVA-T7 to produce progeny virus in most mammalian cells circumvents the necessity to separate the reconstituted MV from the M VA-T7 helper virus. Since all components are expressed transiently, th is system is especially suitable for studying the functions of N, P an d L. Furthermore, it is useful for investigating later steps in the MV life cycle. Copyright (C) 1997 Elsevier Science B.V.