Optimum methods for evaluating virucidal activities of germicides to infectious pancreatic necrosis virus (IPNV) and infectious hematopoietic necrosis virus (IHNV) were studied.
1. Among the fish cell lines examined CHSE-214 and EPC cells were best suited for examining virucidal activities.
2. Cell-associated virus suspension (CAV) was effectively obtained by freezing and thawing cell-sheet culture just before the appearance of cytopathological effects (CPE).
3. CAV of IPNV did not change in infectivity titer during the stocking period of 8 weeks at either -20°C or -80°C. However, infectivity titer of IHNV in CAV significantly decreased infectivity titer at both -20°C and -80°C.
4. Virucidal activities of IPNV and IHNV did not change during 6 h incubation at temperatures from 10°C to 37°C and from 10°C to 15°C, respectively. Hence, 15°C appears to be a reasonable temperature for routine use in this assay system.
5. Toxicities to IPNV and IHNV of germicides other than halogenic compounds were successfully eliminated by 10
2-10
5 dilutions of PBS (-).
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