Reduction of Aichi Virus by Sodium Metasilicate and Calcium Hypochlorite in Suspension

Introduction: Aichi virus (AiV) is a newly emerging virus responsible for gastroenteritis outbreaks worldwide. Currently, there is limited data in literature on effective methods to control the spread of AiV. Therefore, improved chemical methods are being researched to inactivate AiV and to prevent transmission and reduce viral illnesses worldwide. Sodium metasilicate and calcium hypochlorite are known for their antimicrobial properties and used in industry. Hence, their effects against AiV need to be explored.

Purpose: The objective of this research was to determine the ability of sodium metasilicate (SMS) and calcium hypochlorite (Ca(ClO)₂) to inactivate AiV in suspension at room temperature.

Methods: AiV at ~ 5 log PFU/ml was treated with equal volumes of SMS at 5% and 10%, Ca(ClO)₂ at 0.02% and 0.2%, or phosphate buffered saline (pH 7.2 as control) at room temperature for  0.5, 1, and 5 min. At each time-point, treated viruses were initially serially diluted in cell-culture media containing 10% fetal bovine serum (FBS), followed by dilutions in 2% FBS. Viral infectivity was assessed by plaque assays in duplicate using Vero host cells. Data obtained from three replicate treatments were statistically analyzed.

Results: AiV at 5 log PFU/ml was reduced to non-detectable levels after 5 min with both 5% and 10% SMS, but showed insignificant reduction after 0.5 min with both 5% an 10% SMS and 0.59 ± 0.37 log PFU/ml reduction after 1 min with only 10% SMS (P > 0.05). However, Ca(ClO)₂ at both tested concentrations of 0.2% and 0.02% reduced AiV to non-detectable levels after 15 s.

Significance: This study showed that Ca(ClO)₂ at 0.02% could more effectively and rapidly reduce AiV in suspension than 5% or 10% SMS to control the spread of AiV. Thus, Ca(ClO)₂ shows potential for application in industry to control AiV spread.