Human coronavirus inactivation by atmospheric pressure helium plasma

The recent global pandemic of Corona Virus Disease-19 has impacted all aspects of society, producing a growing demand for a powerful virus inactivation method. To assess a potential and mechanism of human coronavirus inactivation using atmospheric pressure plasma (APP) technology, replication of a human coronavirus (HCoV-229E) after He + H 2 O APP plume exposure was evaluated using rhesus monkey kidney epithelial cells. The HCoV-229E titers were reduced by 3 log 10 TCID 50 after the APP exposure for 30 s, showing a strong virus-inactivation efficacy of the APP. It was experimentally verified that the APP produced the liquid-phase reactive oxygen and nitrogen species (RONS) at high rates [e.g. • OH: ∼1.7 nmol s −1 , H 2 O 2 (including H 2 O 2 precursors): ∼9.2 nmol s −1 , NO 2 − (including NO 2 − precursors): ∼3.3 nmol s −1 ]. However, an administration of H 2 O 2 with NO 2 − failed to inactivate the virus and only Mn type superoxide dismutase among several RONS scavengers for • OH, HO 2 • /O 2 •−, 1 O 2 , and • NO/ • NO 2 was significantly effective for the recovery of the APP-induced decrease in the viral titers. This suggests O 2 •− -related chemical reaction in a network of interconnected reactions induced by the APP exposure is very important for the APP-induced virus inactivation. These results provide new insight into a more efficient inactivation method of human coronavirus using APPs.