- Email: [email protected]
Characterization of the infectious hematopoietic necrosis virus (IHNV) carrier state in sockeye salmon (Oncorhynchus nerka)
Abstracts / Fish & Shellfish Immunology 34 (2013) 1635–1691
appeared later at 8 hpi. This immune-triggering response could have affected a high number of processes that seemed to be activated 24 hpi to overcome the Vibrio infection, including the expression of many cytoskeleton molecules, which is indicative of the active movement of hemocytes. Finally, 72 hpi, activity returned to normal levels, and more than 50% of the genes were downregulated in a negative feedback of all of the previously active processes. Conclusions: Using a new version of the R. philippinarum oligo-microarray, a putative timing for the response against a Vibrio infection was established. The results show that the key point to overcome the infection seemed to be 8 hours after the challenge, when we detected immune functions that led to the destruction of the pathogen and the activation of a wide variety of processes related to homeostasis and defense. These results highlight the importance of a fast response in bivalves and the effectiveness of their innate immune system. * Corresponding author.
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markers of these differences in clinical infections, we characterized the genetic fingerprints linked to clinical disease on the VP2 capsid of IPNV using a genomic trace-back system that characterized field isolates from fresh and seawater stages of the production cycle of Atlantic salmon (Salmo salar L) from different study areas formerly classified as high and low risk sites in Norway. Two genetic markers of the virus were identified as the I64T137T217A221T247V252T281N282A319 fingerprint designated as the TA-strain for the clinical form and the V64A137P217T221A247N252S281D282E319 fingerprint designated as the PT-strain for the subclinical form of IPNV infections. The TA-strain was linked to high morbidity (100%) and mortality (62%) while the PT-strain was only linked to high morbidity (90%) with no mortality was observed from this strain at fresh and seawater sites. Structural analysis and antibody cross neutralization assays show that some of the residues encoded by these fingerprints linked differences in virulence to differences in immunogenicity of the VP2 capsid. These findings could play an important role in designing effective disease control programs against IPNV infections in salmonids.
E-mail address: [email protected] (B. Novoa)
* Corresponding author. E-mail address: [email protected] (Ø. Evensen)
O-451. Characterization of the infectious hematopoietic necrosis virus (IHNV) carrier state in sockeye salmon (Oncorhynchus nerka) A. Müller 1, K.A. Garver 1, B.J.G. Sutherland 2, Ben F. Koop B.F. 2, S.C. Johnson 1, *. 1
Aquatic Animal Health Section, Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, British Columbia, Canada; 2 Department of Biology, University of Victoria, Victoria, British Columbia, Canada Abstract A variety of RNA viruses infect farmed and wild marine fish and can have a profoundly negative impact on their populations. For most of these viruses our knowledge of their ecology is limited with important questions such as the effect of carrier states in their maintenance within host populations remaining unanswered. Infectious hematopoietic necrosis virus (IHNv) is a negative-sense single-stranded RNA virus that is a member of the family Rhabdoviridae. This virus is enzootic in British Columbia and it is commonly found in sockeye salmon (Oncorhynchus nerka) stocks where it is known to cause serious disease. Recently, we demonstrated: the presence of IHNv in brain tissues of sockeye salmon surviving a laboratory exposure, as well as the presence of this virus in asymptomatic juvenile sockeye in the marine environment. Taken together these results suggest that individuals within sockeye populations may be lifelong ‘carriers’ of IHNv. To understand how IHNv is maintained within sockeye salmon we are characterizing the transcriptional response of asymptomatic carriers and comparing their responses to those of individuals injected with the viral mimic polyriboinosinic polyribocytidylic acid (pIC) using the cGRASP 44K salmon oligo array. The results of this experiment will be presented and comparisons made to studies that have examined carriers of other fish RNA viruses (nodavirus and infectious pancreatic necrosis virus). * Corresponding author. E-mail address: [email protected] (S.C. Johnson)
O-482. Clinical and subclinical forms of infectious pancreatic necrosis virus infections show specific viral genetic fingerprints that link differences in virulence to immunogenicity S. Mutoloki 1, H.M. Munang'andu 1, Ø. Evensen 1,*. 1 Department of Basic Science and Aquatic Medicine, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., N-0033 Oslo, Norway
Abstract Infectious pancreatic necrosis virus (IPNV) causes clinical and subclinical forms infections in salmonids. To better understand the viral genetic
O-392. Gene expression of MCSFR and perforin in the ovary of pregnant female of surfperch Neoditrema ransonnetii O. Nakamura 1, *, K. Ueda 1, E. Saito 2, S. Tsutsui 1, A. Nozawa 3, K. Kikuchi 3, Y. Suzuki 3. 1
School of Marine Biosciences, Kitasato University, Kanagawa, Japan; School of Medicine, Iwate Medical University, Iwate, Japan; 3 Laboratory of Fisheries, The University of Tokyo, Japan 2
Abstract Viviparity requires highly elaborate control mechanisms in order to modulate immune responses, because the spermatozoa and fetuses express paternal major histocompatibility complex antigens. Though viviparous species are widely distributed among vertebrates, our knowledge on these mechanisms in non-mammalian species is considerably lacking. Embiotocid fish, so called surfperch, is one of the representative groups in viviparous teleost. They have a long gestating period, and brood development exclusively relies on the maternal nutrients secreted in to the ovarian cavity. We have investigated immunological relationship between mother and fetus in Neoditrema ransonnetii, a common surfperch in Japan. Our previous studies showed that the ovarian cavity fluid (OCF) of N. ransonnetii suppressed lymphocyte proliferation and the inhibitory effect on lymphocytes was partially due to prostaglandin E2, which was contained in OCF at high level. Semiquantitative reverse transcription PCR (RTPCR) revealed that expression of TCRa, CD8a and IgM H chain genes were lower in the ovary of pregnant female than that of non-pregnant female. To investigate distribution of macrophages and cytotoxic cells in the ovary during gestation, we cloned and sequenced cDNA of two isotypes of macrophage colony-stimulating factor receptor (MCSFR) and four isotypes of perforin. RT-PCR showed that gene expression patterns of MCSFRs and perforins in various tissues were different between isotypes, but all of them were expressed in the ovary of pregnant female. Gene expression of those in the ovarian tissues and ovarian cavity leucocytes were lower in the gestating mother than that of non-pregnant female. In situ hybridization showed a number of MCSFR-producing cells and perforin-producing cells were distributed beneath the epithelia of ovigerous lamellae in the pregnant fish. After parturition, the ovigerous folds underwent rapid shrinking, flattened out, and those cells were localized at the tissues around large blood vessels in the ovigerous folds. These results provide some further basis for understanding the modulation of immunity in the maternal-fetal interface of gestating female of viviparous teleost. * Corresponding author. E-mail address: [email protected] (O. Nakamura)
appeared later at 8 hpi. This immune-triggering response could have affected a high number of processes that seemed to be activated 24 hpi to overcome the Vibrio infection, including the expression of many cytoskeleton molecules, which is indicative of the active movement of hemocytes. Finally, 72 hpi, activity returned to normal levels, and more than 50% of the genes were downregulated in a negative feedback of all of the previously active processes. Conclusions: Using a new version of the R. philippinarum oligo-microarray, a putative timing for the response against a Vibrio infection was established. The results show that the key point to overcome the infection seemed to be 8 hours after the challenge, when we detected immune functions that led to the destruction of the pathogen and the activation of a wide variety of processes related to homeostasis and defense. These results highlight the importance of a fast response in bivalves and the effectiveness of their innate immune system. * Corresponding author.
1667
markers of these differences in clinical infections, we characterized the genetic fingerprints linked to clinical disease on the VP2 capsid of IPNV using a genomic trace-back system that characterized field isolates from fresh and seawater stages of the production cycle of Atlantic salmon (Salmo salar L) from different study areas formerly classified as high and low risk sites in Norway. Two genetic markers of the virus were identified as the I64T137T217A221T247V252T281N282A319 fingerprint designated as the TA-strain for the clinical form and the V64A137P217T221A247N252S281D282E319 fingerprint designated as the PT-strain for the subclinical form of IPNV infections. The TA-strain was linked to high morbidity (100%) and mortality (62%) while the PT-strain was only linked to high morbidity (90%) with no mortality was observed from this strain at fresh and seawater sites. Structural analysis and antibody cross neutralization assays show that some of the residues encoded by these fingerprints linked differences in virulence to differences in immunogenicity of the VP2 capsid. These findings could play an important role in designing effective disease control programs against IPNV infections in salmonids.
E-mail address: [email protected] (B. Novoa)
* Corresponding author. E-mail address: [email protected] (Ø. Evensen)
O-451. Characterization of the infectious hematopoietic necrosis virus (IHNV) carrier state in sockeye salmon (Oncorhynchus nerka) A. Müller 1, K.A. Garver 1, B.J.G. Sutherland 2, Ben F. Koop B.F. 2, S.C. Johnson 1, *. 1
Aquatic Animal Health Section, Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, British Columbia, Canada; 2 Department of Biology, University of Victoria, Victoria, British Columbia, Canada Abstract A variety of RNA viruses infect farmed and wild marine fish and can have a profoundly negative impact on their populations. For most of these viruses our knowledge of their ecology is limited with important questions such as the effect of carrier states in their maintenance within host populations remaining unanswered. Infectious hematopoietic necrosis virus (IHNv) is a negative-sense single-stranded RNA virus that is a member of the family Rhabdoviridae. This virus is enzootic in British Columbia and it is commonly found in sockeye salmon (Oncorhynchus nerka) stocks where it is known to cause serious disease. Recently, we demonstrated: the presence of IHNv in brain tissues of sockeye salmon surviving a laboratory exposure, as well as the presence of this virus in asymptomatic juvenile sockeye in the marine environment. Taken together these results suggest that individuals within sockeye populations may be lifelong ‘carriers’ of IHNv. To understand how IHNv is maintained within sockeye salmon we are characterizing the transcriptional response of asymptomatic carriers and comparing their responses to those of individuals injected with the viral mimic polyriboinosinic polyribocytidylic acid (pIC) using the cGRASP 44K salmon oligo array. The results of this experiment will be presented and comparisons made to studies that have examined carriers of other fish RNA viruses (nodavirus and infectious pancreatic necrosis virus). * Corresponding author. E-mail address: [email protected] (S.C. Johnson)
O-482. Clinical and subclinical forms of infectious pancreatic necrosis virus infections show specific viral genetic fingerprints that link differences in virulence to immunogenicity S. Mutoloki 1, H.M. Munang'andu 1, Ø. Evensen 1,*. 1 Department of Basic Science and Aquatic Medicine, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., N-0033 Oslo, Norway
Abstract Infectious pancreatic necrosis virus (IPNV) causes clinical and subclinical forms infections in salmonids. To better understand the viral genetic
O-392. Gene expression of MCSFR and perforin in the ovary of pregnant female of surfperch Neoditrema ransonnetii O. Nakamura 1, *, K. Ueda 1, E. Saito 2, S. Tsutsui 1, A. Nozawa 3, K. Kikuchi 3, Y. Suzuki 3. 1
School of Marine Biosciences, Kitasato University, Kanagawa, Japan; School of Medicine, Iwate Medical University, Iwate, Japan; 3 Laboratory of Fisheries, The University of Tokyo, Japan 2
Abstract Viviparity requires highly elaborate control mechanisms in order to modulate immune responses, because the spermatozoa and fetuses express paternal major histocompatibility complex antigens. Though viviparous species are widely distributed among vertebrates, our knowledge on these mechanisms in non-mammalian species is considerably lacking. Embiotocid fish, so called surfperch, is one of the representative groups in viviparous teleost. They have a long gestating period, and brood development exclusively relies on the maternal nutrients secreted in to the ovarian cavity. We have investigated immunological relationship between mother and fetus in Neoditrema ransonnetii, a common surfperch in Japan. Our previous studies showed that the ovarian cavity fluid (OCF) of N. ransonnetii suppressed lymphocyte proliferation and the inhibitory effect on lymphocytes was partially due to prostaglandin E2, which was contained in OCF at high level. Semiquantitative reverse transcription PCR (RTPCR) revealed that expression of TCRa, CD8a and IgM H chain genes were lower in the ovary of pregnant female than that of non-pregnant female. To investigate distribution of macrophages and cytotoxic cells in the ovary during gestation, we cloned and sequenced cDNA of two isotypes of macrophage colony-stimulating factor receptor (MCSFR) and four isotypes of perforin. RT-PCR showed that gene expression patterns of MCSFRs and perforins in various tissues were different between isotypes, but all of them were expressed in the ovary of pregnant female. Gene expression of those in the ovarian tissues and ovarian cavity leucocytes were lower in the gestating mother than that of non-pregnant female. In situ hybridization showed a number of MCSFR-producing cells and perforin-producing cells were distributed beneath the epithelia of ovigerous lamellae in the pregnant fish. After parturition, the ovigerous folds underwent rapid shrinking, flattened out, and those cells were localized at the tissues around large blood vessels in the ovigerous folds. These results provide some further basis for understanding the modulation of immunity in the maternal-fetal interface of gestating female of viviparous teleost. * Corresponding author. E-mail address: [email protected] (O. Nakamura)