Abstract: Provided is a method for evaluating the viral clearance capability of a virus removal medium, comprising the steps of: (a) adding a viral capsid-containing liquid to a solution to be purified; (b) contacting the virus removal medium with the solution to be purified that has been supplemented with the viral capsid-containing liquid to harvest a purified solution; and (c) quantifying a total viral capsid in the solution to be purified before the purification and a total viral capsid in the purified solution.

Abstract: Provided are a parvovirus derived from an unconcentrated cell culture supernatant, having a infectivity titer of 109 TCID50/mL or more and an {infectivity titer (TCID50/mL)}:{impurity protein concentration (ng/mL)} ratio more than 5000:1; and a method of producing such a high-infectivity titer and high-purity parvovirus.

Abstract: Provided are a parvovirus derived from an unconcentrated cell culture supernatant, having a infectivity titer of 109 TCID50/mL or more and an {infectivity titer (TCID50/mL)}:{impurity protein concentration (ng/mL)} ratio more than 5000:1; and a method of producing such a high-infectivity titer and high-purity parvovirus.

Abstract: A method for stably and easily producing a parvovirus having a high infectivity titer is provided. The problem is solved by a method for producing a parvovirus having an infectivity titer as high as 108 TCID50/mL or more in a culture supernatant, comprising the steps of inoculating a seed virus of the parvovirus into a culture substrate comprising host cells having a cell density of 1/500 to 1/20 of the cell density of the host cells confluently grown and a medium at a multiplicity of infection of 0.0001 to 0.1, culturing for a period of 5 to 11 times the doubling time of the host cells, and recovering a culture supernatant.

Abstract: Provided is a filtration method for the step of removing viruses in a process of producing a protein preparation during which an intermediate protein preparation with a high protein concentration flows at high pressure to a virus removal filter. The filtration method employs a virus removal filter which has a close fitting nozzle of which the inlet at least has a pressure resistance of 600 kPa or more, and an effective area of the virus removal membrane of at least 0.0001 m2 and no more than 0.03 m2. An intermediate protein preparation with the protein concentration raised to at least 20 mg/ml and no more than 100 mg/ml by means of a purification process flows down to said virus removal filter under conditions in which the inlet pressure of the intermediate protein preparation is at least 150 kPa and no more than 600 kPa, the average protein filtration speed is at least 1.

Abstract: A method for stably and easily producing a parvovirus having a high infectivity titer is provided. The problem is solved by a method for producing a parvovirus having an infectivity titer as high as 108 TCID50/mL or more in a culture supernatant, comprising the steps of inoculating a seed virus of the parvovirus into a culture substrate comprising host cells having a cell density of 1/500 to 1/20 of the cell density of the host cells confluently grown and a medium at a multiplicity of infection of 0.0001 to 0.1, culturing for a period of 5 to 11 times the doubling time of the host cells, and recovering a culture supernatant.

Abstract: Provided is a filtration method for the step of removing viruses in a process of producing a protein preparation during which an intermediate protein preparation with a high protein concentration flows at high pressure to a virus removal filter. The filtration method employs a virus removal filter which has a close fitting nozzle of which the inlet at least has a pressure resistance of 600 kPa or more, and an effective area of the virus removal membrane of at least 0.0001 m2 and no more than 0.03 m2. An intermediate protein preparation with the protein concentration raised to at least 20 mg/ml and no more than 100 mg/ml by means of a purification process flows down to said virus removal filter under conditions in which the inlet pressure of the intermediate protein preparation is at least 150 kPa and no more than 600 kPa, the average protein filtration speed is at least 1.

Abstract: Calcium silicate monohydrate (2CaO.sup.. SiO.sub.2.sup.. H.sub.2 O) can be produced in a coating which has been formed by a coating material containing silica sol alone or silica sol and other additives such as aggregate, viscosity increasing agent, etc. by subjecting the coating to a chemical treatment such as heat-treatment, ultra-violet ray irradiation treatment, etc. in the presence of water and a calcium compound which may be present either in the coating material, or in the treating liquid, or in an object to be coated. The film which contains the calcium silicate monohydrate produced by said chemical treatment has remarkably high hardness and is excellent in water-resistance, water-imperviousness, weather-resistance, and heat-resistance.

Abstract: The surface of an inorganic substrate comprising cement, concrete, gypsum or mixtures thereof is treated with a silicate solution or a silica sol comprising a monovalent alkali metal containing component, an ammonium containing component and a silica containing component at a molar ratio of 1:1.about. 10:4.about.5000 corresponding to M.sub.2 O:[R.sub.1 R.sub.2 R.sub.3 R.sub.4 N].sub.2 O: SiO.sub.2 wherein M is Li, K or Na; and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each represent a hydrocarbon group or an alkanol group. The underlying inorganic substrate thus has a modified surface layer thereon having a thickness of less than 50 mm, which functions to protect and prevent deterioration of the underlying surface of said inorganic substrate.