Photodynamic inactivation of an RNA enveloped virus in goat colostrum

The primary objective of this study was to determine if a RNA enveloped vir us can be inactivated in goat colostrum using methylene blue (MB) and 1h of illumination (photodynamic inactivation (PI)). The effects of illumination on the virucidal properties of MB were studied in translucent media as wel l as colostrum. Concentrations of MB evaluated were 10, 1.0, 0.1 and 0.01 m uM. Bovine viral diarrhea virus (BVDV) was used as a model for caprine arth ritis-encephalitis virus (CAEV). Virus, immunoglobulin, bacterial and colif orm levels were determined before and after treatments. In transparent media, concentrations of MB >0.1 muM inactivated virus regar dless of time, with or without light exposure. Sixty minutes of light treat ment significantly reduced viral levels in samples containing 0.01 muM MB a s compared to dark treatment. In colostrum, light treatment significantly i nactivated virus in samples containing 1.0 and 10 P mu MB. Concentrations o f immunoglobulin were not adversely affected, and total bacterial and colif orm counts increased. We concluded that PI of a RNA enveloped virus appears to be achievable in g oat colostrum without lowering immunoglobulin concentrations, or creating a hazardous degree of bacterial and coliform proliferation. The clinical rel evance of this experiment is that PI has the potential to inactivate CAEV i n goat colostrum, thus providing the goat industry an alternative to heat t reatment of colostrum. However, further refinement of this technique is war ranted. (C) 2001 Elsevier Science B.V. All rights reserved.