Effect Of Physicochemical Factors On The Stability Of Pseudorabies Virus In Vitro

Pseudorabies(PR),also known as Aujeszky’s disease,is caused by Pseudorabies Virus(PRV).Is a multi-animal co-infection,the main susceptible animals are pigs,cattle,sheep,rabbits,mice,cats and other mammals.With the exception of pigs,PRV infections in other animals often result in severe itching and death.Pigs are the natural host of PRV,and the clinical symptoms after infection with PRV vary with age.The younger pigs are susceptible to PRV,mainly presenting neurological symptoms,while the adult pigs mainly presenting respiratory symptoms and other subclinical symptoms.Sows are characterized by reproductive difficulties that can lead to miscarriage,fetal absorption,or mummified fetuses.PRV is latent and can exist in infected sows for a long time,causing lifelong poisoning in recovered sows,causing serious economic losses to breeders and posing great challenges to the prevention and control of PR.At present,there are two main ways to prevent and control PR.One is to immunize pigs with vaccine to reduce the susceptibility of pigs.Second,improve the biological safety level of farms,eliminate pathogens and cut off the spread of pathogens.Biosecurity prevention and control has advantages of low comprehensive cost and obvious prevention and control effect,which will be the development trend of PR prevention and control and other epidemic prevention and control methods in the future.To improve the level of biosafety in prevention and control of epidemic diseases,it is necessary to have a comprehensive and detailed understanding of the biological characteristics of pathogens so as to develop reasonable,economical and efficient prevention and control measures.More than 100 years after PRV was discovered,much of the data on its biological properties is missing,Limited by the experimental technology and equipment conditions at that time,the existing data are often not accurate,comprehensive and detailed.Over the last 100 years,PRV have evolved.The existing data are no longer suitable for scientific research reference and production and application guidance.In order to fully understand the biological characteristics of PRV,this study designed a variety of physicochemical factor and controllable condition variables to process PRV in vitro.Such as temperature,humidity,p H,UVC,drying,sunlight,disinfection drugs,etc.,To explore its biological characteristics.The design of this research scheme is inclined to production application,and also simulates various production environment conditions.PRV was found to be temperature sensitive,When the ambient temperature is higher than 70℃,virus inactivation only takes a few seconds.When the ambient temperature is between 50℃ and 70℃,the infectivity of PRV decreases rapidly with the increase of temperature.When the ambient temperature is from 26℃ to 50℃,PRV can survive for about one month at most.However,under the conditions of low temperature(0℃～4℃)or ultra-low temperature(0℃～-80℃),it can survive for several months,and even maintain the titer stability for a long time.The infectivity of PRV is affected by the p H value of the environment.When the p H value is lower than 4 or greater than 11,PRV is quickly inactivated.When p H value is 4～6,or 9～11,the infectivity of PRV decreases rapidly.When p H is 6～9,PRV activity is relatively stable.PRV is sensitive to uv of C band(UVC),but has some resistance to uv of other band.The effect of uv on PRV is related to the wavelength,intensity and exposure time of uv.The shorter the uv wavelength,the higher the intensity,the better the inactivation effect of PRV.Ambient humidity has a great influence on the stability of PRV.Under normal temperature,PRV can maintain its infectivity for about one month in the environment of liquid neutral water.In the case of natural slow drying,usually can survive for about a week,in the dry outdoor environment,can only survive for 1～2 days.For repeated freezing-thawing,the freezing temperature is-80℃,the dissolution temperature is 20℃ or 37℃,such rapid temperature difference of100℃,PRV has a strong tolerance.Under this condition,PRV kept titer basically unchanged after repeated freezing and thawing for 40 times.The tolerance of PRV to disinfection drugs is mainly related to the concentration of disinfection drugs and disinfection principle.The higher the concentration of the same disinfectant,the better the inactivation effect of PRV.In terms of disinfection principle,PRV is sensitive to surface ionic active agent,acid and alkali,strong oxidant and other disinfection drugs.In addition,sunlight exposure also has a good inactivation ability to PRV,but it is greatly affected by sunlight intensity,ultraviolet intensity,ambient temperature and airflow factors.Generally,the infectivity of PRV is affected by multiple factors,which can be either synergistic or antagonistic.In actual production and application,it is necessary to combine the actual situation and make a comprehensive analysis to guide production.The purpose of this study is to comprehensively and in detail understand the biological characteristics of PRV.To provide theoretical and technical support for the prevention and control of pig farm PR and other diseases,and to provide new ideas and methods for the study of virus biological characteristics.