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Hypochlorous acid (HOCl) solutions were evaluated for their virucidal ability against a low pathogenic avian influenza virus (AIV), H7N1. HOCl solutions containing 50, 100 and 200 ppm chlorine (pH 6) or their sprayed solutions (harvested in dishes placed at 1 or 30 cm distance between the spray nozzle and dish) were mixed with the virus with or without organic materials (5% fetal bovine serum: FBS). Under plain diluent conditions (without FBS), harvested solutions of HOCl after spraying could decrease the AIV titer by more than 1,000 times, to an undetectable level (< 2.5 log10TCID50/ml) within 5 sec, with the exception of the 50 ppm solution harvested after spraying at the distance of 30 cm. Under the dirty conditions (in the presence of 5% FBS), they lost their virucidal activity. When HOCl solutions were sprayed directly on the virus on rayon sheets for 10 sec, the solutions of 100 and 200 ppm could inactivate AIV immediately after spraying, while 50 ppm solution required at least 3 min of contact time. In the indirect spray form, after 10 sec of spraying, the lids of the dishes were opened to expose the virus on rayon sheets to HOCl. In this form, the 200 ppm solution inactivated AIV within 10 min of contact, while 50 and 100 ppm could not inactivate it. These data suggest that HOCl can be used in spray form to inactivate AIV at the farm level.

Scallop shell powder produced by calcination process − the average diameter of the powder particles being 20 µm (SSP) − was further ground into nano-sized particles, with average diameter of 500 nm, here designated CaO-Nano. Solution of CaO-Nano could inactivate avian influenza virus within 5 sec, whereas the solution of SSP could not even after 1 hr incubation. CaO-Nano solution could also inactivate Newcastle disease virus and goose parvovirus within 5 sec and 30 sec, respectively. The virus-inactivating capacity (neutralizing index: NI>3) of the solution was not reduced by the presence of 20% fetal bovine serum. CaO-Nano solution seems to be a good candidate of materials for enhancement of biosecurity in farms.

The efficacy and stability of scallop shell powder (SSP) were investigated, in terms of its capacity to inactivate avian influenza virus (AIV), and compared with slaked lime (SL). An environmental simulation was conducted by emulating sunlight and wet-dry conditions. The powders were collected at consecutive 2-week intervals under sunlight and upon every resuspension. These materials were tested by mixing them with AIV and incubating the mixture for 3 min or 20 h, followed by AIV titration. At the same time, a pH buffering test was conducted by neutralization with Tris-HCl. The results revealed that SSP and SL have high alkalinity and excellent ability to inactivate AIV. In a simulated harsh environment, SSP and SL retained a satisfactory ability to inactivate AIV within 20 h throughout the experimental procedure. However, SSP was able to inactivate AIV during a short contact period (3 min), even under harsh conditions, and it was more resistant than SL to neutralization.