Example 15
Total RNA was extracted from tissues using the “RNAqueous-Midi kit” (Ambion Inc., Austin, Tex.). Ten μg of RNA were hybridized with a mix of 32P-labeled RNA probes. The 32P-labeled RNA probe mix was prepared by in vitro transcription using the “In vitro transcription kit”, CK-3, and custom template sets were provided by BD Biosciences/Pharmingen (San Diego, Calif.). The hybridized RNAs were treated with RNAse, using the “RNAse protection Assay kit” (BD Biosciences), precipitated and the protected fragments were resolved on vertical sequencing (10% acrylamide) gels. Following electrophoresis, the gels were dried and exposed to X-ray film (Kodak-X-Omat) and Phosphorlmager screen (Molecular Dynamics, Sunnyvale, Calif.). The signals on the screen were analyzed by Phosphorlmager Image-Quant software. The RNAse protection assay was performed using RNA samples of at least 3 to 5 individual mice per each virus. At least two independently prepared virus stocks were used for RNA levels analysis.