In vitro antiviral activity of hypothiocyanite against A/H1N1/2009 pandemic influenza virus

Abstract

Influenza virus spreads via small particle aerosols, droplets and fomites, and since it can survive for a short time on surfaces, can be introduced into the nasal mucosa before it loses infectivity. The hypothiocyanite ion (OSCN-), product of the lactoperoxidase/H2O2/SCN- system of central airways, is emerging as an important molecule for innate defense mechanism against bacteria, fungi and viruses. Here we demonstrated that OSCN(-) displays virucidal activity in vitro against the A/H1N1 2009 pandemic influenza virus. The concentration required to inhibit viral replication by 50% was 2 μM when virus were challenged directly with OSCN- before cell inoculation. These values were even lower when inoculated cells were maintained in contact with enzyme free-OSCN- in the culture medium. The last experimental conditions better reflect those of tracheobronchial mucosa, where HOSCN/OSCN- is retained in the air-liquid interface and inactivates both the viruses approaching the epithelium from outside and those released from the inoculated cells after the replication cycle. Importantly no OSCN- cytotoxicity was observed in the cellular system employed. The lack of toxicity in humans and the absence of damage on surfaces of fomites suggest a potential use of OSCN- to avoid mucosal and environmental transmission of influenza virus. Since hypothiocyanite is normally present in human airways a low risk of viral resistance is envisaged. In vivo confirmatory studies are needed to evaluate the appropriate dose, regimen and formulation.

Keywords: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; 5-thio-2-nitrobenzoic acid; 5′5 dithio-bis-2-nitrobenzoate; A/H1N1/2009; ATCC; American tissue culture collection; CO(2); DNA; DTNB; DUOX; Disinfection; FBS; HA; HIV; HOSCN; Hypothiocyanite; In vitro; Infection control; Influenza prophylaxis; Influenza treatment; LPO; MDCK; MEM; MTT; Madin-Darby Canine kidney; NA; NADPH; Neuroaminidase; OD; OSCN(−); OSCN(−) lactoperoxidase; PBS; RNA; RSV; SCN(−); SDS; TCID; TNB; TPCK; carbon dioxide; deoxyribonucleic acid; dual oxidase; fetal bovine serum; hemagglutinin; human immunodeficiency virus; hypothiocyanite anion; hypothiocyanous acid; l-1-tosylamide-2-phenylethyl chloromethyl ketone; lactoperoxidase; minimal essential medium; neuraminidase; nicotinamide adenine dinucleotide phosphate; optical density; phosphate buffered saline; rRT-PCR; respiratory syncytial virus; reverse transcriptase real-time polymerase chain reaction; ribonucleic acid; sequence detection systems software; thiocyanate; tissue culture infectious dose.