Quantitative assessment of the virucidal activities of three commercial disinfectants against human in-fected highly pathogenic avian influenza viruses subtype H5 / 中华微生物学和免疫学杂志

ABSTRACT

Objective To quantitatively assess the virucidal activities of three commercial disin-fectants against human infected highly pathogenic avian influenza viruses subtype H5. Methods The 50%tissue culture infective dose ( TCID50 ) of avian influenza viruses was calculated. Quantitative suspension test was performed to evaluate the efficacy of three disinfectants. In that test, 105 TCID50 of avian influenza viru-ses were exposed to different disinfectants at different concentrations for different times with or without the in-terference with fetal bovine serum ( FBS) simulating the contaminated condition. The residual infectivity was determined by endpoint titration in Madin-Darby canine kidney ( MDCK) cells. The detail steps were that the mixture of viruses and disinfectants was inoculated at 37℃ with 5% CO2 for 1 hour. Then, it was re-placed by virus dilution medium and further incubated for 18 to 20 hours. ELISA was performed for the cal-culation of TCID50 . The titers of residual viruses were calculated according to Reed and Muench method. The low pathogenic avian influenza virus H9N2 was chosen as the control in this study. Results The re-mained infectivities of three viruses after 1 minute exposure to 1% Virkon solution were below the limit of de-tection (1. 0 lgTCID50/100 μl). Exposing to 0. 5% Virkon solution decreased the viral titers of H5N1 and H9N2 viruses below the detection limit and reduced the titer of H5N6 virus to 1. 75 lgTCID50/100 μl. The virucidal efficacy of 0. 25% Virkon solution against some of the detected viruses was achieved by increasing the exposure time to 5 minutes. The 84 Disinfectant solutions at concentrations of 10%, 5% and 2. 5% low-ered the viral titers of three viruses below the detection limit of 1. 0 lgTCID50/100 μl, but the 1. 25% 84 Disinfectant solution only lowered the viral titers to 1. 25-2. 5 lgTCID50/100 μl. The similar results were ob-served in groups treated with SOLARSEPT solutions. 1% 84 Disinfectant solution didn′t show any virucidal activity against the three viruses after 1 minute of exposure even when the exposure time was extended to 5 minutes. Under the contaminated condition, 1% Virkon solution, 10% and 5% 84 Disinfectant solutions as well as 100% and 50% SOLARSEPT solutions lowered the viral titers below 1. 0 lgTCID50/100μl. Conclu-sion The three commercial disinfectants (1% Virkon solution, 10% 84 Disinfectant solution and SOLAR-SEPT solution) were efficient virucides for highly pathogenic avian influenza viruses subtype H5 even under the contaminated condition. Increasing the exposure time had no significant effects on the efficacy of three disinfectants after the virucidal activities were neutralized by enough viruses. No significant differences in vi-rucidal activities of three disinfectants against HPAI H5 viruses and LPAI H9 virus were observed.