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Downstream Processing
Published in Sarfaraz K. Niazi, Disposable Bioprocessing Systems, 2016
A combination of methods—inactivation, adsorption, and size exclusion—is available. The FDA requires demonstration of virus clearance by two methods. Examples of inactivation procedures are solvent and detergent, chemical treatments, low pH, or microwave heating. Methods of adsorption utilize chromatography, and removal by mechanical or molecular size exclusion uses normal (forward) and tangential flow filtration methods. The treatments with solvents/detergent, low pH, or microwave heating all have significant limitations in their ability to inactivate small nonenveloped viruses. Low pH inactivation of murine retroviruses is reported to be highly dependent on time, temperature, and pH, and relatively independent of the recombinant protein type or conductivity conditions outlined. Heating is considered one of the most reliable methods for virus inactivation because of the variation in stability of each virus genome to heat or temperature.
Pathogens in Soils and on Plants
Published in Eliot Epstein, LAND APPLICATION of SEWAGE SLUDGE and BIOSOLIDS, 2002
Straub et al. (1992) measured the inactivation rate (k = log−10 reduction per day) of poliovirus type 1 and bacteriophages MS2 and PRD-1 in a laboratory study using two desert soils. Biosolids were added to a Brazito sand loam and Pima clay loam. They found that temperature and soil texture were the most important factors controlling inactivation when the soil was kept moist. As the temperature rose from 15 to 40°C, the inactivation rate for poliovirus and bacteriophage MS2 increased; whereas, for the bacteriophage PRD-1, a significant increase in inactivation occurred only at 40°C. Clay soils afforded more protection than sandy soils to all three viruses. Reduction in moisture content to less than 5% completely inactivated all three viruses within 7 days at 15°C. Thus, a combination of moisture reduction and high temperature is effective in virus inactivation. These studies, under laboratory conditions using soil columns and constant parameters, can point to possible trends, but should not be taken as definitive behavior of organisms in the environment. Soils undergo fluctuations in moisture and temperature. These fluctuations, especially desiccation and high surface temperatures, will destroy pathogens.
Fate of Wastewater Constituents in Soil and Groundwater: Pathogens
Published in G. Stuart Pettygrove, Takashi Asano, Irrigation With Reclaimed Municipal Wastewater–A Guidance Manual, 1985
The survival rates of pathogenic bacteria in soil normally vary from one day to several months. Many factors affect the survival of enteri c bacteria in soil. Increased soil moisture content, cool er temperatures, and higher organic matter content tend to favor l anger survival, but extremely acidic or alkaline conditions, sunlight, and antagonistic microflora are opposing factors to survival. Protozoa and helminths appear to survive as long as enteric bacteria in soil, although ascaris ova may remain viable much longer. Depending on the nature of the soil, temperature, pH, and moisture content, enterovirus survival has been reported to vary from 25 to 170 days. Virus inactivation is promoted by dissaggregation of viral clumps, presence of chloride salts, high temperature and pH, and virucidal chemical species such as ammonia. Suspended organic matter in wastewater (virus-solid association) is believed to have some protective effect on virus survival.
Chlorhexidine-filled porous ceramic coating fabricated by the aerosol deposition method for immediate and long-term enveloped virus inactivation
Published in Journal of Asian Ceramic Societies, 2022
Taku Goto, Yoichi Yamada, Takeji Ueda, Sumiko Shiota, Mitsugu Sohma, Jun Akedo
The antiviral activity of the samples was tested following ISO 21702 as follows. An influenza virus A/PR/8/34 (H1N1) suspension containing 106–107 plaque forming units (pfu)/mL was dropped onto the test sample. The sample was covered with a film and left at 25°C for 10 min, 2 h, or 24 h. The viruses on the sample were collected by washing with soybean casein digest lecithin polysorbate (SCDLP) medium (10 mL), and the solution containing the viruses was diluted with SCDLP medium. The solution was applied to a confluent six-well plate containing Madin-Darby canine kidney cells at 37°C for 1 h under 5% CO2. The supernatant was replaced with 0.8% oxoid agar and plates were incubated for 24 to 48 h at 37°C under 5% CO2. The cells were fixed with 5% glutaraldehyde and stained with methylene blue. The virus infection titer was calculated from the number of counts of plaques and the dilution factor. The virus inactivation ratio was calculated by dividing the virus infection titer of samples by the virus infection titer of the control.