Properties of defective interfering particles of Sindbis virus generated in vertebrate and mosquito cells.

Defective interfering (DI) particles of Sindbis virus were generated during serial, undiluted passage of a cloned virus stock in both chick embryo fibroblast (CEF) cells and Aedes albopictus mosquito cells. DI particle-containing stocks were identified by their ability to interfere with standard virus replication and to synthesize small DI RNA species in the cell type in which they were generated. DI RNA species generated during serial passage in CEF cells were able to replicate in both vertebrate and A. albopictus cells. Some of the DI RNA species generated during serial passage in A. albopictus cells replicated efficiently in both cell types while others, sometimes present in the same DI particle stock, failed to replicate in cells of vertebrate origin. These results suggest that evolution of DI RNA species during serial passage of Sindbis virus in mosquito cells may result in the loss or alteration of nucleotide sequences required for RNA synthesis in vertebrate cells.