Inactivation of Baculoviral Mid-gut Gland Necrosis (BMN) Virus by Ultraviolet Irradiation, Sunlight Exposure, Heating and Drying

Abstract

Inactivation of BMN virus by ultraviolet (U.V.) irradiation, sunlight exposure, heating and drying treatment was investigated by means of the infection method of the author using larval and post-larval kuruma shrimp, Penaeus japonicus. Test shrimp sampled on day 4 after waterborne inoculation were examined for nuclear hypertrophy of the mid-gut gland epithelial cells in fresh squash preparations under the dark field microscope. The results obtained are summarized as follows;
U.V. irradiation (15 W U.V. lamp, 30cm in distance) : BMN virus was inactivated within 20 minutes post-irradiation. The U.V. dosage during this period was measured to 4.1×10⁵μW·sec/cm².
Summer sunlight exposure : The virus was inactivated within 3 hours post-exposure at about 30°C.
Heating : The virus was inactivated within 120 minutes at 45°C, 30 minutes at 50 and 55°C, 5 minutes at 60°C.
Drying : The virus absorbed in a filter paper was inactivated within 1.5 hours postdrying at about 30°C.