PREPARATION OF VIRUS INCLUSION STAINS I. Preparation of the orange-green (O-G) protein stain. Stain powders should be prepared separately as follows: A. Add 1 gm of Calcomine Orange to 100 ml of 2 -methoxyethanol and stir thoroughly. B. Add 1 gm of Luxol Brilliant Green BL to 100 ml of 2-methoxyethanol and stir thoroughly. C. Prepare the final staining solution by mixing one part distilled water, one part of the orange dye and eight parts of the green dye. This solution is stable and can be used as needed. The stains should be stored in brown bottles which are tightly capped. II. Preparation of the Azure A nucleoprotein stain: A. Azure A powder should be stirred into 100 ml of 2-methoxyethanol to achieve a 0.1% dye content (Azure A powders vary in dye content). This stain should be stored in a brown bottle which is tightly capped. B. Prepare a 0.2M solution of dibasic sodium phosphate heptahydrate. It is important to use a hydrated (not anhydrous) form. C. Prepare the final staining solution by adding one part of the phosphate solution to nine parts of Azure A. This solution must be prepared fresh with each staining sequence. Do not reuse it.