Inactivation Regularity Of Common Disinfectants Against Novel Human Adenovirus Type 55 Strain

Objective: In recent years, high incidence of novel adenoviruses infections in households, schools, army and hospitals has become an increasing problem both in China and abroad. The novel adenovirus vaccine production is far more behind demanded. The prevention of novel adenoviruse outbreak are mainly depending on disinfection, mask and clinical medicine. In order to find effective disinfection methods, this study is to evaluate the natural dying regularity of adenovirus type 55(AdV55) and also its inactivation regularity by common disinfectants,which are of great significance for epidemic prevention and daily life.Content: Adenovirus(Ad) is a non enveloped, double-stranded DNA virus of adenoviridae family. Adenoviruses comprise a diverse group of viruses including pathogenic strains causing several serious conditions, such as respiratory disease,conjunctivitis and gastroenteritis, resulting in considerable economic losses in many countries. However, relatively few investigators have examined inactivating regularity in the disinfection process; this topic is about the following aspects to discuss the inactivating regularity of novel AdV55:(1) Make comparisons of the inactivating regularity of common disinfectants against AdV55.(2) Find the influence-factors of AdV55 inactivating effect(such as temperature,concentration of organics).(3) Make comparisons of resistance of AdV55 and PV-Ⅰ to sodium hypochlorite disinfectant.(4) Find the natural dying regularity of a novel AdV55.Methods:(1) Make comparisons of the inactivating regularity of common disinfectants.Experimental procedure was designed according to the provisions of the 2002 version of “Technical Standard for Disinfection”, choosing high level disinfectant solution(sodium hypochlorite solution, peracetic acid), the moderate level disinfectant(iodine volts), low level disinfectant(Chlorhexidine acetate, benzalkonium chloride),different disinfectant concentrations, contact time, organic interference and temperature were designed.(2) The influence-factors of inactivating effect to AdV55(such as temperature,concentration of organics).1) Organic matter impact testThree groups were designed; bovine serum albumin was 30 g/L, 3 g/L and none.Sodium hypochlorite disinfectant was prepared at concentration being 1.25 times design concentration. After water-bath at 20℃for 10 min, 800 μl disinfectant and 200μl virus suspension containing organic matter was mixed immediately, recorded time.Till the scheduled time, immediately removed 100 μl solution to 0.9ml neutralizer test tubes respectively, neutralized for 10 min,diluted virus suspension by 10-fold,absorbed liquid sample, with inoculation on monolayer cell culture plate cultured at37℃with 5% CO2 incubator, inoculated four wells at each titer. Sterile deionized water was used instead of disinfectants as positive control group. Measured virus titre log reduction and calculated inactivation effect.2) The temperature impact testSodium hypochlorite disinfectant was prepared at concentration being 1.25 times design concentration. The temperature conditions were 4℃, 10℃, 20℃, 30℃, and 40℃ respectively. The virus inactivation test process is as same as the organic matter impact test. Sterile deionized water was used instead of disinfectants as positive control group. Measured virus titre log reduction and calculated inactivation effect.(3) The comparison of AdV55 and PV-Ⅰ resistanceIn accordance with the provisions of the 2002 version of “Technical Standard for Disinfection”, with the sodium hypochlorite as the representative, in the same conditions to compare the PV and AdV55 resistance to sodium hypochlorite disinfectant.(4) Natural dying regularity of AdV55 exposed under different temperaturesPrepared virus suspension(106-107), with trace sampler absorbing 40 μl suspension on glass slide, which was put in dish. At 4℃, 25℃ and 37℃, till the scheduled time, took out the glass slide to 1 ml cell culture, diluted virus suspension by 10-fold, absorbed liquid sample with inoculation on monolayer cell culture plate cultured at 37℃ carbon dioxide incubator, respectively, inoculated four wells at each titer. Virus log reduction was measured.Results:(1) The inactivating regularity of common disinfectants to AdV55When sodium hypochlorite disinfectant with available chlorine concentration of400 mg/L contacting 20 min 600 mg/L of peracetic acid disinfectant contacting20 min,iodine volts with available iodine 1000mg/L contacting above 40 min, the inactivated effect of adenovirus can reach more than 4.00. While the sodium hypochlorite disinfectant with available chlorine concentration of 600 mg/L contacting 20 min 800mg/L of peracetic acid disinfectant contacting 20 min, volts iodine with available iodine 1500 mg/L contacting above 40 min, adenovirus can be completely inactivated.And low-efficacydisinfectants inactivatedeffica-cy are less than 4.00.(2) The influence-factors of inactivating effect to AdV55(such as temperature,concentration of organics)1) Effect of organic interference on AdV55 inactivation to sodium hypochloriteThe test showed organic interference in virus suspension can directly down the inactivation effect of disinfectant. With sodium hypochlorite disinfectant at the concentration of 400mg/L available chlorine, the concentration of calf serum albumin as organic interference ranged from 0% to 3%, the disinfectant contact time was 5, 10,15, 20 min, the AdV55 inactivation effect was sharply different..2) Effect of temperature on AdV55 inactivation to sodium hypochloriteThe test showed the temperature can directly enhance the inactivation effect of disinfectant. With sodium hypochlorite disinfectant at the concentration of 400mg/L available chlorine, temperature at 4℃, 10℃, 20℃, 30℃, 40℃, the inactivation effect was enhanced, from 3.96 to 6.13 average log reduction in virus titer at 20 min.(3) The comparison of AdV55 and PV-ⅠresistanceWhen sodium hypochlorite disinfectant with available chlorine concentration of600 mg/L contacting 10 min the inactivated effect of AdV55 and PV-Ⅰ can reach more than 4.00. With available chlorine concentration 600 mg/L of sodium hypochlorite solution contacting 20 min AdV55 can be inactivated completely, while poliovirus can be inactivated above 90%. The resistance to sodium hypochlorite disinfectant of AdV55 is close to the PV-Ⅰ.(4) Natural dying regularity of AdV55 exposed under different temperaturesThe result showed that AdV55 can survive for a long period in the environment and exhibit high thermal stability. The natural dying time of AdV55 on glasses was nearly a week at 25°C, and about 24 h at 37°C. The AdV55 can live nearly weeks on glasses at 4℃, the titer log reduction was down from 8.0 to 4.0 in a week.Conclusion:This study evaluated the natural dying regularity of a novel adenovirus type 55(AdV55) and also its inactivation regularity by some common disinfectants and inactivated influence factors. High-efficacy disinfectants and some intermediate efficacy disinfectants under the appropriate concentration and contacting time are effective to adenovirus type 55, while low-efficacy disinfectants are invalid.Adenovirus inactivation are infected by organic matter, the concentration of the disinfectant and the influence of multiple factors such as time, temperature, therefore various factors should be considered, so as to achieve the ideal effect of inactivated adenovirus.