Effects of Temperature on the Susceptibility of Largemouth Bass to Largemouth Bass Virus

Abstract

Temperature is an environmental variable thought to influence the susceptibility of fish to infectious diseases. This study demonstrated that juvenile largemouth bass Micropterus salmoides that were experimentally infected with largemouth bass virus (LMBV; family Iridoviridae) experienced greater mortality at 30°C than at 25°C. Juvenile largemouth bass were exposed to equal doses of LMBV and held at three temperatures: 25, 30, and 35°C. Fish held at 30°C suffered mortality at a higher rate than fish held at 25°C and had higher viral loads (viral genomes per gram of tissue) at the time of death. The LMBV-injected fish held at 35°C suffered mortality at rates equal to those of sham-injected controls, suggesting that stressful manipulation at temperatures approaching the upper lethal limit can induce mortality in fish independently of viral infection. These results suggest that temperature is an important determinant of host survival and viral replication in the LMBV system.