Inactivation of Surface-Associated Viruses in Real Indoor Environments by a Humidification System Generating...

Area of Science:

• Environmental microbiology
• Virology
• Public health

Background:

• Vaporized free chlorine, mainly hypochlorous acid (HOCl), is used for indoor microbial control.
• Virus-specific susceptibility and molecular factors influencing HOCl efficacy are not well understood.

Purpose of the Study:

• To assess the virucidal efficacy of vaporized HOCl against specific viruses.
• To investigate the molecular determinants of viral susceptibility to HOCl.

Main Methods:

• Evaluated HOCl effects on echovirus 30, influenza A/H1N1, and adenovirus type 3 under controlled indoor conditions.
• Quantified infectious titers using TCID50 assays.
• Employed computational fluid dynamics (CFD) for dispersion analysis and structural analysis of oxidation-sensitive residues.

Main Results:

• Significant infectivity reductions for echovirus 30 (99.0%) and influenza A/H1N1 (99.9%).
• No significant reduction observed for adenovirus type 3 (p = 0.142).
• Fewer oxidation-sensitive residues were found in adenovirus proteins compared to susceptible viruses, particularly on surface-exposed domains.

Conclusions:

• Viral susceptibility to vaporized HOCl is correlated with the presence and location of oxidation-sensitive amino acid residues.
• The findings suggest a mechanistic framework for HOCl virucidal activity, though direct biochemical validation is needed.