Transcription in vitro of infectious haematopoietic necrosis virus, a fish rhabdovirus.

Transcription in vitro by the RNA polymerase of infectious haematopoietic necrosis virus (IHNV), a salmonid rhabdovirus, was investigated using different reaction conditions to maximize RNA synthesis. The use of HEPES buffer rather than Tris buffer, and the addition of S-adenosyl-L-methionine to the reactions resulted in a sixfold increase in RNA synthetic activity to 6400 pmol UMP incorporated/mg viral protein/hour. The RNA transcripts produced in this system contained polyadenylated species which co-migrated with IHNV mRNA species 2, 3, 4 and 5 from IHNV-infected cells. The transcripts were shown to be functional mRNA species by their ability to direct the synthesis of viral proteins in vitro.