Here are a couple of the latest on LMB virus. It seems like ages since I've actually posted something like this before Ewest could get to it!
Journal of Aquatic Animal Health 17:304–314, 2005
Effects of Factors Related to Water Quality and Population Density on the Sensitivity of Juvenile Largemouth Bass to Mortality Induced by Viral Infection
KATE R. INENDINO AND EMILY C. GRANT
Department of Natural Resources and Environmental Sciences,
University of Illinois, Champaign, Illinois 61820, USA
DAVID P. PHILIPP
Center for Aquatic Ecology, Illinois Natural History Survey,
and Program in Ecology and Evolutionary Biology, University of Illinois,
Champaign, Illinois 61820, USA
TONY L. GOLDBERG*
Department of Veterinary Pathobiology, College of Veterinary Medicine,
and Program in Ecology and Evolutionary Biology, University of Illinois,
Champaign, Illinois 61820, USA
Abstract.—Environmental stressors can predispose fish to mortality from infectious disease. This
study examined the effects of two factors, water quality and physical crowding, on the responses
of fish to viral infection. Juvenile largemouth bass Micropterus salmoides were experimentally
inoculated with largemouth bass virus (LMBV), an emerging pathogen in the family Iridoviridae.
In separate experiments, fish were exposed to various concentrations of nitrate (0, 40, 200, and 400 mg/L) and were housed at either high or low population densities. Survival time, viral load (quantity of virus in tissues), and body condition were measured as outcomes. Nitrate, as well as other water quality parameters such as ammonia, nitrite, and pH, affected mortality rates and viral loads in complex ways. Paradoxically, increased nitrate concentrations were associated with reduced mortality rates in juveniles exposed to LMBV. In general, rapid fluctuations in the concentrations of dissolved toxins had greater impact on sensitivity to viral infection than did persistently high levels of these toxins. Fish housed at high density experienced increased mortality rates,
elevated viral loads, and reduced body condition compared with fish held at low density. These
results demonstrate that both physiochemical and social environmental stressors can affect the
survival and condition of largemouth bass infected with LMBV.
Journal of Aquatic Animal Health 17:315–322, 2005
Effects of Practices Related to Catch-and-Release Angling on Mortality and Viral Transmission in Juvenile Largemouth Bass Infected with Largemouth Bass Virus
EMILY C. GRANT AND KATE R. INENDINO
Department of Natural Resources and Environmental Sciences, University of Illinois, Champaign, Illinois 61820, USA
WILLIAM J. LOVE
Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana, Illinois 61802, USA
DAVID P. PHILIPP
Center for Aquatic Ecology, Illinois Natural History Survey,
and Program in Ecology and Evolutionary Biology,
University of Illinois, Champaign, Illinois 61820, USA
TONY L. GOLDBERG*
Department of Veterinary Pathobiology, College of Veterinary Medicine,
and Program in Ecology and Evolutionary Biology,
University of Illinois, Urbana, Illinois 61802, USA
Abstract.—Largemouth bass virus (LMBV; family Iridoviridae) has recently emerged as a causative
agent in fish kills of largemouth bass Micropterus salmoides. Little is known about how the virus is transmitted or what factors predispose fish to mortality subsequent to infection. Concern has nevertheless arisen that activities related to recreational angling may affect transmission dynamics and may alter the susceptibility of infected fish to clinical disease. This study examined the separate effects of two angling-related factors on the susceptibility of juvenile largemouth bass
to mortality from LMBV infection and on the transmission of LMBV from infected to uninfected
fish. The first factor was hook-and-line angling. Infected fish that underwent a simulated angling treatment did not experience higher mortality or have higher viral loads in their tissues than those that were not angled. The second factor was direct contact between infected and uninfected fish, as would occur in live wells and holding tanks. The LMBV was transmitted from infected to uninfected fish through water, even when direct contact was prevented. Transmission of LMBV between infected and uninfected fish separated by a fenestrated barrier was nearly as efficient as LMBV transmission between infected and uninfected fish that were allowed direct contact. These
results imply that angling itself may have only minimal effects on the survival of largemouth bass infected with LMBV but that angling-related practices that place infected and uninfected fish
together in a limited water volume may facilitate viral transmission. Partitioning or cooling of live wells and holding tanks, as well as limiting their use, could reduce LMBV-associated mortality and viral transmission.
