Survival of Infectious Hematopoietic Necrosis Virus Held Under Various Environmental Conditions

Abstract

Dehydration of infectious hematopoietic necrosis virus (IHNV) from water at 4 and 10 °C resulted in only partial inactivation, but dehydration from Hanks' balanced salt solution (HBSS) and homogenized fish tissue resulted in total loss of virus infectivity within 7 days. Survival was not affected by pH between 6 and 8, but virus infectivity was significantly reduced at pH 5 and 9. Water hardness from 20 to 250 mg/ℓ (as CaCO3) did not significantly reduce virus infectivity. Salinity distinctly affected IHNV survival: storage in artificial seawater, filtered ocean water, HBSS. and Earle's balanced salt solution (EBSS) equally reduced virus titers. The addition of protein to deionized water and EBSS and HBSE resulted in increased survival. Survival of IHNV was inversely proportional to HBSS concentration and was highest when it was frozen in media supplemented with 10% calf serum. Virus survival was good at −70 and −20 °C, but virus infectivity decreased sharply with an increase of temperature above 4 °C; increasingly poor survival occurred at 15. 21, 28, and 32 °C. Freezing and thawing of IHNV had no effect if the media contained 10% protein; however, freezing in deionized water resulted in a significant loss of virus infectivity. Key words: virology, virus survival, laboratory storage, environmental effects