Impact of low temperature on the efficacy of chlorous acid water and sodium hypochlorite solution for inactivating avian influenza virus on material surfaces

Chlorous acid water is a type of chlorine-based disinfectant with chemical properties distinct from those of sodium hypochlorite solution, which is in common use. In this study, we evaluated the inactivation efficacy of chlorous acid water against avian influenza virus deposited on material surfaces, in comparison with sodium hypochlorite solution. First, the intrinsic antiviral activity of both disinfectants was examined under conditions free of amino acids and proteins. The results demonstrated that the 99% (IC99), 99.9% (IC99.9), and 99.99% inhibitory concentrations (IC99.99) were all approximately half those of sodium hypochlorite solution, indicating that chlorous acid water possesses slightly stronger inactivation activity. Next, the efficacy against protein-containing virus deposited on material surfaces (stainless steel, plastic, and rubber) was evaluated under conditions simulating a poultry house environment. At room temperature, both disinfectants exhibited equivalent inactivation capacity; however, a marked difference was observed under low-temperature conditions. Specifically, the efficacy of chlorous acid water was maintained or enhanced, whereas that of sodium hypochlorite solution declined, with the required concentration increasing approximately 2- to 3-fold. Taken together, these findings demonstrate that chlorous acid water exhibits antiviral activity comparable to or exceeding that of sodium hypochlorite solution, while retaining its efficacy even at low temperatures and in the presence of proteins. These properties suggest that chlorous acid water may be a particularly useful disinfectant in real-world settings such as poultry houses operating under low-temperature conditions.