COMMERCIAL IN CONFIDENCE METHOD The disinfectant test was preformed using the AOAC (USA) drying method with some modifications. The canine parvovirus was suspended in WHO hard water to give a TCID 50 of approximately 10 -9 . The virus suspension (0.2 ml) was placed into sterile universals and spread evenly. To each aliquot of virus "Stalosan A" was added, 0.5 g per Cm 2 (equivalent to 50 gram per m 2 ). The disinfectant was allowed to remain in contact with separate aliquots of virus for 5 mins, 15 mins and 30 mins. respectively. After these exposure times, the disinfectant powder/virus was resuspended in 2.0 ml of MEM tissue culture growth medium. Tissue culture plates were set up to contain 1.8 ml of MEM in each group of 9 wells. 0.2 ml. of the mixture from a chosen petri dish was then placed into the first well of a group and mixed with the MEM. 0.2 ml. from this 10 -1 well was then transferred to the next well and so on up to a dilution of 10 -9 . To one of the aliquots of virus 2.0 ml of hard water only was added and a virus control thus prepared. This was titrated in cell-culture medium as above. Aliquots of 0.025 ml of each dilution were placed onto preseeded 96 well microtitre plates (0.05 ml of CRFK cell suspension per well) 4 wells in a column were used for each tenfold dilution of disinfectant mixture, and 8 for the virus control. The 3 end columns of the microtitre plate were used as cell controls (0.05 ml of cells was mixed with 0.025 ml of MEM only). The plates were incubated at 37 o C in a CO 2 incubator for 6 days, and then fixed in 20% acetone. The virus, was detected using a CPV monoclonal antibody and a goat anti-rat immunoperoxidate enzyme assay. The Virus titres were calculated by the Karber method. RESULTS - Porcine Parvovirus Disinfectant "Stalosan F" Contact times Wet conditions virus titre TCLD 50 5 minutes 3.33 15 minutes 3.00 30 minutes 2.67 PPV. Virus control titre (Wet) = 7.50 A Log reduction of 4.0 or greater is a pass. Disinfectant Toxiticy - cell control = 1.5 Log reduction 4.17 4.50 4.83 CONCLUSION The Veterinary Disinfectant "Stalosan F" (dry disinfectant powder) reduced the titre of porcine parvovirus by a titre of greater than 4.0 under wet conditions. Under normal AOAC test procedures the virus suspension is dried and then a dilution of disinfectant under test is used to resuspended the virus. This is then left at room temperature for 10 minutes before the virus dilutions are made. With the disinfectant powder it is difficult to determine whether the "efficacy" of the disinfectant is due to the adsorption of the virus suspension into the powder, or to its active chemical ingredients. These results for "Stalosan F" in no way constitute official approval under the MAFF Diseases of Animal (Approved Disinfectants) order 1978 (as amended)
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