Inactivation of Bombyx mori nucleopolyhedrovirus occluded virions (BmNPV OVs) was promoted by the synergistic effect of sodium hypochlorite (NaClO) and sodium carbonate (Na₂CO₃) mixtures. Bioassay results using silkworm neonate larvae demonstrated that BmNPV OVs in occlusion bodies (OBs) were inactivated at 100ppm of free chlorine when 0.1ml of the viral suspension (1.05×10⁸ OBs/ml) was treated for 5min with 0.9ml of a 0.3% (w/v) Na₂CO₃-added solution of NaClO. This combination mixture showed a higher value of LC₅₀ (10^8.30OBs/ml) than that of 2.5% formaldehyde (10^4.23OBs/ml) with a 5 min-chemical treatment. On the other hand, all the test larvae died of nucleopolyhedrosis when BmNPV OBs (1.05×10⁸OBs/ml) were treated for 5min with 0.3% (w/v) Na₂CO₃ or three solutions of NaClO which contained free chlorine of 100, 250 and 500ppm. In order to confirm the practical use of the Na₂CO₃-added solution of NaClO, we also checked the pH stability and inactivation of BmNPV under circumstances of a lower pH created by adding the silkworm artificial diet into the combination mixture.

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