%0 Journal Article %A Patel, Arvind H. %A Elliott, Richard M. %T Characterization of Bunyamwera virus defective interfering particles %D 1992 %J Journal of General Virology, %V 73 %N 2 %P 389-396 %@ 1465-2099 %R https://doi.org/10.1099/0022-1317-73-2-389 %I Microbiology Society, %X In an attempt to isolate conditional lethal amber nonsense mutants of Bunyamwera virus, five variants were found which produced small plaques on BHK and mouse L cells. Characterization of these variants by Northern blotting showed that they synthesized defective (subgenomic) RNAs derived from the L RNA segment. No subgenomic M or S segment RNAs were detected. The defective L RNAs were shown to be packaged into virus particles, and four of five preparations caused interference with the multiplication of standard virus. When defective-containing preparations were mixed with standard virus and grown in doubly infected cells a reduction in titre of standard virus of up to 400-fold was observed. Hence these preparations most probably contained defective interfering (DI) particles. Novel DI-specific polypeptides were synthesized in DI virus-infected cells. These novel proteins could be precipitated by antisera raised against either the N or C terminus, or both, of the L protein. Nucleotide sequence analysis of cloned cDNA to prominent DI RNAs in three different defective virus preparations revealed that the DI RNA in each case had suffered a single internal deletion of the L segment while retaining the 5′- and 3′-terminal sequences. The extent of the deletion ranged between 72% and 77% of the L RNA segment. Our results suggest that these DI particles may have arisen during the attempted isolation of Bunyamwera virus amber mutants on mouse L cells, since defective/subgenomic RNAs derived from the L and M segments were readily generated in mouse L cells but not in BHK cells, following infection with wild-type virus. %U https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-73-2-389