The use of phenothiazine dyes to inactivate bovine viral diarrhea virus in goat colostrum.

The objectives of this study were to determine the optimal concentration of phenothiazine dye required to inactivate bovine viral diarrhea virus (BVDV) in goat colostrum following 60 min of illumination and determine if immunoglobulin concentration is affected by this technique. In addition, the potential of continuous agitation of colostrum during illumination to affect viral kill was investigated. This experiment was designed to more closely approximate on-farm use than a previous pilot study performed by the same investigators. Bovine viral diarrhea virus was used as a model for caprine arthritis-encephalitis virus. Goat colostrum containing BVDV was illuminated for 60 min following the addition of either methylene blue (MB) or methylene violet (MV). Four different concentrations of each dye were evaluated. Illumination was performed in a small, portable chest-type freezer equipped on the inside with white fluorescent lights. Some samples were continuously rocked during illumination, while others remained stationary. Virus levels were determined before and after illumination. Immunoglobulin concentrations were determined for time 0 and 60 min. One microM MB reduced virus to undetectable levels following 60 min of illumination. A concentration of 20 microM MV was required to reduce virus levels to zero. Agitation of colostrum samples had no effect with either MB or MV on whether virus levels were reduced. High concentrations of MB and MV had no important effect on immunoglobulin concentrations.