Jacob Gregg
Jacob is a Fish Biologist at the Marrowstone Marine Field Station, Nordland, WA.
Science and Products
Filter Total Items: 44
Energetic cost of ichthyophonus infection in Juvenile Pacific Herring (Clupea pallasii)
The energetic costs of fasting and Ichthyophonus infection were measured in juvenile Pacific herring (Clupea pallasii) in a lab setting at three temperatures. Infected herring incurred significant energetic costs, the magnitude of which depended on fish condition at the time of infection (fat versus lean). Herring that were fed continually and were in relatively good condition at the time of infec
Authors
Johanna J. Vollenweider, J.L. Gregg, R.A. Heintz, P.K. Hershberger
Factors controlling the early stages of viral haemorrhagic septicaemia epizootics: Low exposure levels, virus amplification and fish-to-fish transmission
Viral haemorrhagic septicaemia virus, Genogroup IVa (VHSV), was highly infectious to Pacific herring, Clupea pallasii (Valenciennes), even at exposure doses occurring below the threshold of sensitivity for a standard viral plaque assay; however, further progression of the disease to a population‐level epizootic required viral amplification and effective fish‐to‐fish transmission. Among groups of h
Authors
P.K. Hershberger, J.L. Gregg, C.A. Grady, L.M. Hart, S.R. Roon, J. R. Winton
Passive immunization of Pacific herring against viral hemorrhagic septicemia.
The plasma of Pacific herring Clupea pallasii that survived laboratory-induced viral hemorrhagic septicemia (VHS) epizootics contained humoral substances that, when injected into naive animals, conferred passive immunity against the disease. Among groups exposed to viral hemorrhagic septicemia virus (VHSV), injection of donor plasma from VHS survivors resulted in significantly greater survival (50
Authors
P.K. Hershberger, J.L. Gregg, C.A. Grady, S. E. LaPatra, J. R. Winton
Larval and juvenile Pacific herring Clupea pallasii are not susceptible to infectious hematopoietic necrosis under laboratory conditions
Infectious hematopoietic necrosis (IHN) leads to periodic epidemics among certain wild and farmed fish species of the Northeast (NE) Pacific. The source of the IHN virus (IHNV) that initiates these outbreaks remains unknown; however, a leading hypothesis involves viral persistence in marine host species such as Pacific herring Clupea pallasii. Under laboratory conditions we exposed specific patho
Authors
L.M. Hart, G.S. Traxler, K.A. Garver, J. Richard, J.L. Gregg, C.A. Grady, Gael Kurath, P.K. Hershberger
Effects of environmental temperature on the dynamics of ichthyophoniasis in Juvenile Pacific Herring (Clupea pallasii)
The effects of temperature and infection by Ichthyophonus were examined in juvenile Pacific herring (Clupea pallasii) maintained under simulated overwinter fasting conditions. In addition to defining parameters for a herring bioenergetics model (discussed in Vollenweider et al. this issue), these experiments provided new insights into factors influencing the infectivity and virulence of the parasi
Authors
J.L. Gregg, Johanna J. Vollenweider, C.A. Grady, R.A. Heintz, P.K. Hershberger
Viral replication in excised fin tissues (VREFT) corresponds with prior exposure of Pacific herring, Clupea pallasii (Valenciennes), to viral haemorrhagic septicaemia virus (VHSV)
Procedures for a viral replication in excised fin tissue (VREFT) assay were adapted to Pacific herring, Clupea pallasii, and optimized both to reduce processing time and to provide the greatest resolution between na??ve herring and those previously exposed to viral haemorrhagic septicaemia virus (VHSV), Genogroup IVa. The optimized procedures included removal of the left pectoral fin from a euthan
Authors
C.A. Grady, J.L. Gregg, R.M. Wade, J. R. Winton, P.K. Hershberger
Susceptibility of three stocks of pacific herring to viral hemorrhagic septicemia
Laboratory challenges using specific-pathogen-free Pacific herring Clupea pallasii from three distinct populations indicated that stock origin had no effect on susceptibility to viral hemorrhagic septicemia (VHS). All of the populations were highly susceptible to the disease upon initial exposure, with significantly greater cumulative mortalities occurring in the exposed treatment groups (56.3-64.
Authors
P.K. Hershberger, J.L. Gregg, C.A. Grady, R.M. Collins
Sequence analysis of the internal transcribed spacer (ITS) region reveals a novel clade of Ichthyophonus sp. from rainbow trout
The mesomycetozoean parasite Ichthyophonus hoferi is most commonly associated with marine fish hosts but also occurs in some components of the freshwater rainbow trout Oncorhynchus mykiss aquaculture industry in Idaho, USA. It is not certain how the parasite was introduced into rainbow trout culture, but it might have been associated with the historical practice of feeding raw, ground common carp
Authors
C. Rasmussen, M. K. Purcell, J.L. Gregg, S. E. LaPatra, J. R. Winton, P.K. Hershberger
Release of infectious cells from epidermal ulcers in Ichthyophonus sp.–infected Pacific Herring (Clupea pallasii): Evidence for multiple mechanisms of transmission
A common clinical sign of ichthyophoniasis in herring and trout is “sandpaper” skin, a roughening of the epidermis characterized by the appearance of small papules, followed by ulceration and sloughing of the epithelium; early investigators hypothesized that these ulcers might be a means of transmitting the parasite, Ichthyophonus sp., without the necessity of ingesting an infected host. We examin
Authors
Paul K. Hershberger, Jacob L. Gregg, R. M. Kocan
Kinetics of viral shedding provide insights into the epidemiology of viral hemorrhagic septicemia in Pacific herring
Losses from infectious diseases are an important component of natural mortality among marine fish species, but factors controlling the ecology of these diseases and their potential responses to anthropogenic changes are poorly understood. We used viral hemorrhagic septicemia virus (VHSV) and a laboratory stock of Pacific herring Clupea pallasii to investigate the kinetics of viral shedding and its
Authors
Paul K. Hershberger, Jacob L. Gregg, James R. Winton, Courtney Grady, Rachael Collins
Chronic and persistent viral hemorrhagic septicemia virus infections in Pacific herring
Chronic viral hemorrhagic septicemia virus (VHSV) infections were established in a laboratory stock of Pacific herring Clupea pallasii held in a large-volume tank supplied with pathogen-free seawater at temperatures ranging from 6.8 to 11.6°C. The infections were characterized by viral persistence for extended periods and near-background levels of host mortality. Infectious virus was recovered fro
Authors
Paul K. Hershberger, Jacob L. Gregg, James R. Winton, Cortney A. Grady, L. Taylor
Amplification and transport of an endemic fish disease by an introduced species
The introduction of American shad from the Atlantic to the Pacific coast of North America in the late 1800’s and the subsequent population expansion in the 1980’s resulted in the amplification of Ichthyophonus sp., a Mesomycetozoean parasite of wild marine fishes. Sequence analysis of the ribosomal DNA gene complex (small subunit and internal transcribed spacer regions) and Ichthyophonus epidemiol
Authors
Paul Hershberger, Bjorn Leeuw, Gregg Jacob, Courtney Grady, Kenneth Lujan, Susan Gutenberger, Maureen K. Purcell, James Woodson, James Winton, Michael Parsley
Science and Products
Filter Total Items: 44
Energetic cost of ichthyophonus infection in Juvenile Pacific Herring (Clupea pallasii)
The energetic costs of fasting and Ichthyophonus infection were measured in juvenile Pacific herring (Clupea pallasii) in a lab setting at three temperatures. Infected herring incurred significant energetic costs, the magnitude of which depended on fish condition at the time of infection (fat versus lean). Herring that were fed continually and were in relatively good condition at the time of infec
Authors
Johanna J. Vollenweider, J.L. Gregg, R.A. Heintz, P.K. Hershberger
Factors controlling the early stages of viral haemorrhagic septicaemia epizootics: Low exposure levels, virus amplification and fish-to-fish transmission
Viral haemorrhagic septicaemia virus, Genogroup IVa (VHSV), was highly infectious to Pacific herring, Clupea pallasii (Valenciennes), even at exposure doses occurring below the threshold of sensitivity for a standard viral plaque assay; however, further progression of the disease to a population‐level epizootic required viral amplification and effective fish‐to‐fish transmission. Among groups of h
Authors
P.K. Hershberger, J.L. Gregg, C.A. Grady, L.M. Hart, S.R. Roon, J. R. Winton
Passive immunization of Pacific herring against viral hemorrhagic septicemia.
The plasma of Pacific herring Clupea pallasii that survived laboratory-induced viral hemorrhagic septicemia (VHS) epizootics contained humoral substances that, when injected into naive animals, conferred passive immunity against the disease. Among groups exposed to viral hemorrhagic septicemia virus (VHSV), injection of donor plasma from VHS survivors resulted in significantly greater survival (50
Authors
P.K. Hershberger, J.L. Gregg, C.A. Grady, S. E. LaPatra, J. R. Winton
Larval and juvenile Pacific herring Clupea pallasii are not susceptible to infectious hematopoietic necrosis under laboratory conditions
Infectious hematopoietic necrosis (IHN) leads to periodic epidemics among certain wild and farmed fish species of the Northeast (NE) Pacific. The source of the IHN virus (IHNV) that initiates these outbreaks remains unknown; however, a leading hypothesis involves viral persistence in marine host species such as Pacific herring Clupea pallasii. Under laboratory conditions we exposed specific patho
Authors
L.M. Hart, G.S. Traxler, K.A. Garver, J. Richard, J.L. Gregg, C.A. Grady, Gael Kurath, P.K. Hershberger
Effects of environmental temperature on the dynamics of ichthyophoniasis in Juvenile Pacific Herring (Clupea pallasii)
The effects of temperature and infection by Ichthyophonus were examined in juvenile Pacific herring (Clupea pallasii) maintained under simulated overwinter fasting conditions. In addition to defining parameters for a herring bioenergetics model (discussed in Vollenweider et al. this issue), these experiments provided new insights into factors influencing the infectivity and virulence of the parasi
Authors
J.L. Gregg, Johanna J. Vollenweider, C.A. Grady, R.A. Heintz, P.K. Hershberger
Viral replication in excised fin tissues (VREFT) corresponds with prior exposure of Pacific herring, Clupea pallasii (Valenciennes), to viral haemorrhagic septicaemia virus (VHSV)
Procedures for a viral replication in excised fin tissue (VREFT) assay were adapted to Pacific herring, Clupea pallasii, and optimized both to reduce processing time and to provide the greatest resolution between na??ve herring and those previously exposed to viral haemorrhagic septicaemia virus (VHSV), Genogroup IVa. The optimized procedures included removal of the left pectoral fin from a euthan
Authors
C.A. Grady, J.L. Gregg, R.M. Wade, J. R. Winton, P.K. Hershberger
Susceptibility of three stocks of pacific herring to viral hemorrhagic septicemia
Laboratory challenges using specific-pathogen-free Pacific herring Clupea pallasii from three distinct populations indicated that stock origin had no effect on susceptibility to viral hemorrhagic septicemia (VHS). All of the populations were highly susceptible to the disease upon initial exposure, with significantly greater cumulative mortalities occurring in the exposed treatment groups (56.3-64.
Authors
P.K. Hershberger, J.L. Gregg, C.A. Grady, R.M. Collins
Sequence analysis of the internal transcribed spacer (ITS) region reveals a novel clade of Ichthyophonus sp. from rainbow trout
The mesomycetozoean parasite Ichthyophonus hoferi is most commonly associated with marine fish hosts but also occurs in some components of the freshwater rainbow trout Oncorhynchus mykiss aquaculture industry in Idaho, USA. It is not certain how the parasite was introduced into rainbow trout culture, but it might have been associated with the historical practice of feeding raw, ground common carp
Authors
C. Rasmussen, M. K. Purcell, J.L. Gregg, S. E. LaPatra, J. R. Winton, P.K. Hershberger
Release of infectious cells from epidermal ulcers in Ichthyophonus sp.–infected Pacific Herring (Clupea pallasii): Evidence for multiple mechanisms of transmission
A common clinical sign of ichthyophoniasis in herring and trout is “sandpaper” skin, a roughening of the epidermis characterized by the appearance of small papules, followed by ulceration and sloughing of the epithelium; early investigators hypothesized that these ulcers might be a means of transmitting the parasite, Ichthyophonus sp., without the necessity of ingesting an infected host. We examin
Authors
Paul K. Hershberger, Jacob L. Gregg, R. M. Kocan
Kinetics of viral shedding provide insights into the epidemiology of viral hemorrhagic septicemia in Pacific herring
Losses from infectious diseases are an important component of natural mortality among marine fish species, but factors controlling the ecology of these diseases and their potential responses to anthropogenic changes are poorly understood. We used viral hemorrhagic septicemia virus (VHSV) and a laboratory stock of Pacific herring Clupea pallasii to investigate the kinetics of viral shedding and its
Authors
Paul K. Hershberger, Jacob L. Gregg, James R. Winton, Courtney Grady, Rachael Collins
Chronic and persistent viral hemorrhagic septicemia virus infections in Pacific herring
Chronic viral hemorrhagic septicemia virus (VHSV) infections were established in a laboratory stock of Pacific herring Clupea pallasii held in a large-volume tank supplied with pathogen-free seawater at temperatures ranging from 6.8 to 11.6°C. The infections were characterized by viral persistence for extended periods and near-background levels of host mortality. Infectious virus was recovered fro
Authors
Paul K. Hershberger, Jacob L. Gregg, James R. Winton, Cortney A. Grady, L. Taylor
Amplification and transport of an endemic fish disease by an introduced species
The introduction of American shad from the Atlantic to the Pacific coast of North America in the late 1800’s and the subsequent population expansion in the 1980’s resulted in the amplification of Ichthyophonus sp., a Mesomycetozoean parasite of wild marine fishes. Sequence analysis of the ribosomal DNA gene complex (small subunit and internal transcribed spacer regions) and Ichthyophonus epidemiol
Authors
Paul Hershberger, Bjorn Leeuw, Gregg Jacob, Courtney Grady, Kenneth Lujan, Susan Gutenberger, Maureen K. Purcell, James Woodson, James Winton, Michael Parsley