Evaluation of the inactivation performance under physical and chemical conditions against human infected H9N2 avian influenza viruses

Objective Assess and determine inactivation effect of heat, .ultraviolet (UV) light and three disinfectants against human infected H9N2 avian influenza virus in laboratory. Methods Suspension containing with 1010.67 TCID50/ml viral was exposed to 50 ℃, 56 ℃, 60 ℃, 65 ℃ for 10 to 60 minutes and UV every 10 interval minutes from 10 to 80 minutes. The residual viruses after physical treatment were determined through half of tissue culture infective dose (TCID50) with MDCK cells and calculated by Reed-Muench method . Suspension with 1010.37EID50/ml quantitative virus was applied to equal volume of 10% 84 sanitizer, 75% ethanol, 1% Virkon solution and incubated for 1 minute to 15 minutes respectively. The residual viral activity would be evaluated by inoculating in SPF chicken embryo. When the virus titer dropped by 4 lgTCID50/ml or virus in chicken embryo culture was observed to be negative, the physical and chemical treatment was considered effective. Results Human infected H9N2 avian influenza virus titer decreased by 4.02 lgTCID50 at 56 ℃ for 15 minutes, and after 30 minutes at 56 ℃ or 10 minutes at 60 ℃/65 ℃, the post-viral titer would decline below the detection level. 20 minutes of UV irradiation would lead to a 5.67 log reduction, and after 70 minutes lighted, the virus titer fell below the detection level. Virus proliferation was not detected after 3 minutes of disinfection with 10% 84 sanitizer, 75% ethanol and 1% Virkon. Conclusions We should note that it is necessary to meet the specific condition to effectively inactivate the human infected H9N2 avian influenza virus. Our study provides an experimental basis for the biosafety operation of human infected H9N2 avian influenza virus. Key words: Human infected avian influenza virus; H9N2 subtype; Inactivation assessment; Laboratory biosafety