• Korean Journal of Microbiology
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• v.35 no.3
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• pp.226-230
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• 1999

To characterize the Korean isolate of infeciious hematopoietic necrosis virus (IHNV-PRT), a partial DNA fragment G gene of the MNV-PRT was amplified by RT-PCR. cloned inlo pGEM-T easy vector and analyzed for nucleotlde sequences. The size of the PCR pmduct was about 442 bp. The nucleotlde sequence homologies ofthe G gene of IHNV-PRT were 95%, 94%, 94% 94%, 93%, 53%. respectively. with those of foreign isolates of IHNV, IHNV-RB-76. IHNV-LR-73, MNV-K, IHNV-WRAC, Im-SRCV, IHNV-Col-85. However, it showed 81% homology with that of other fish rhabdovirus, hisame rhabdovirus (HRV). Frou~ the rcsults of deduced amino acid sequence homology analysis. G protein of IHNV-PRT showed 96% hornologies with those of foreign isolates of IHNV but 89% homology with that of HRV These results indicaled that, even though G gene of IHIW-PRT showed low homology with that of HRY it was highly conserved among different strains of THNV.

• Journal of fish pathology
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• v.23 no.1
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• pp.1-8
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• 2010

Infectious hematopoietic necrosis virus (IHNV) is the causative agent of IHN, one of the most serious viral diseases of salmonid fish. In this study, glycoprotein (G) gene nucleotide sequence of isolated IHNV RtWanju09 from Jeollabuk-do province was analyzed to evaluate their genetic relatedness to worldwide isolates. As the result, it was revealed that IHNV RtWanju09 isolate belongs to JRt Shizuoka lineage with IHNV RtPy91 and RtJe00. The genetic diversity of G gene between RtWanju09 isolate and RtPy91 isolate from Gangwon-do province was 1.77% and maximum nucleotide diversity among the JRt Shizuoka lineage in Korea was 3.03% during the past 20 years, supporting that the continuous evolution has been occurred among JRt Shizuoka isolates. It was believed that IHNV RtWanju09 isolate has been introduced by the movement of contaminated eggs with IHNV from Gangwon-do to Jeollabuk-do by the reason that the eyed eggs in Jeollabuk-do province used to be obtained from Gangwon-do province. In this study, the domestic transfer of IHNV was firstly investigated by the transfer history of eggs and the phylogenetic analysis using IHNV glycoprotein gene sequence.

• Journal of fish pathology
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• v.35 no.2
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• pp.157-165
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• 2022

Single-cycle viruses generated by reverse genetic technology are replication-incompetent viruses due to the elimination of gene(s) essential for viral replication, which provides a way to overcome the safety problem in attenuated viruses. Infectious hematopoietic necrosis virus (IHNV) is a major pathogen causing severe damage in cultured salmonid species. In the present study, we generated a single-cycle IHNV lacking the transmembrane and cytoplasmic domain in the G gene (rIHNV-GΔTM) and evaluated the prophylactic potential of rIHNV-GΔTM in rainbow trout (Oncorhynchus mykiss). To produce rIHNV-GΔTM, IHNV G protein-expressing Epithelioma papulosum cyprini (EPC) cells were established. However, as the efficiency of rIHNV-GΔTM production in EPC cell clones was not high, fish were immunized with a low-tittered single-cycle virus (1.5 × 10² PFU/fish). Despite the low dose, the single-cycle IHNV induced significant protection in rainbow trout against IHNV infection, suggesting high immunogenicity of rIHNV-GΔTM. No significant difference in serum ELISA titers against IHNV between the rIHNV-GΔTM immunized group and the control group suggests that the immunized dose of rIHNV-GΔTM might be too low to induce significant humoral adaptive immune responses in rainbow trout. The involvement of adaptive cellular immunity or innate immunity in the present significantly higher protection by the immunization with rIHNV-GΔTM should be further investigated to know the protection mechanism.

• Journal of fish pathology
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• v.36 no.2
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• pp.389-394
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• 2023

Infectious hematopoietic necrosis virus (IHNV) is s significant viral pathogen affecting cultured rainbow trout (Oncorhynchus mykiss) in Korea. In this study, five monoclonal antibodies (mAbs) (IHNV-1, 2, 3, 4, and 5) were produced using purified IHNV. Reactivities of these mAbs were analyzed by western blot (WB), enzyme-linked immunosorbent assay (ELISA), and indirect fluorescent antibody test (IFAT). These mAbs recognized glycoprotein (69 kDa, IHNV-1), nucleocapsid protein (39 kDa, IHNV-3, 4, and 5), or phosphoprotein (27 kDa, IHNV-2) of IHNV by WB analysis. ELISA results indicated that these five mAbs were specific to IHNV without showing any cross-reactivity against other fish viruses (hirame rhabdovirus, infectious pancreatic necrosis virus, and viral hemorrhagic septicemia virus). IFAT demonstrated specific fluorescence signals of IHNV-infected epithelioma papulosum cyprini (EPC) cells, whereas no reactivity of normal EPC cells was observed. These mAbs can be very useful for immuno-diagnosis of IHNV infection.

• Journal of fish pathology
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• v.31 no.1
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• pp.1-8
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• 2018

Causative agent of infectious hematopoietic necrosis (IHN) belonging to genus Novirhabdovirus (Rhabdoviridae). Economic losses caused by IHNV are serious in mainly Oncorhynchus spp. including rainbow trout O. mykiss and Atrantic salmon Salmo salar. IHNV was initially found by endemic presence in U.S. West Coast for sockeye salmon fry O. nerka and chinook salmon fry O. tshawytscha in the 1950s, and it has spread to Japan, Korea and Taiwan in the 1970s, and also to Italy and France in the 1990s. Currently, IHNV is detectable in many parts of the world, including Russia and South America. Mortality due to IHNV infection in fish with ${\leq}0.5g$ of body weight reaches 60% to 100%, while the mortality reduces by fish growing. In recent years, onset of IHNV infection has increased also in fish with large sizes. Here, we introduce molecular epidemiology and virulence changes of IHNV in East Asia, furthermore, we discuss on future prospects in IHNV researches.

• Journal of fish pathology
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• v.7 no.1
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• pp.13-22
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• 1994

To identify the immunogens of a PRT strain of Infectious Hematopoietci Necrosis Virus (IHNV) isolated from cultrued fish in Korea (Park et al, 1993). a panel of 4 monoclonal antibodies (MAbs) against IHNV-PRT strain and two polyclonal antisera from rainbow trout survived IHN disease were prepared. Proteins of purified IHNV-PRT strain were analysed on 10% SDS-PAGE and transferred onto NC paper and were incubated with the antibody solutions. With the polyclonal antibodies, four bands ($M_1$, $M_2$, G and 90Kd) were detected and the band density was in the order of $M_2$ > 90Kd > $M_1$ > G. However, with the MAbs, only two bands(G and 90Kd) were detected. The origin of 90Kd protein was not clear but maybe cell. All the results represented that among the five proteins of IHNV-PRT strain (Park et al., 1993), $M_2$, $M_1$ and G proteins were immunogens and $M_2$ protein was the strongest one.

• Journal of fish pathology
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• v.25 no.3
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• pp.257-262
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• 2012

A reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) assay was evaluated to monitor infectious hematopoietic necrosis virus (IHNV) from artificially infected rainbow trout Oncorhynchus mykiss. The cumulative mortalities of fish challenged with IHNV at $10^{6.5}\;TCID_{50}$/fish, $10^{5.5}\;TCID_{50}$/fish and $10^{4.5}\;TCID_{50}$/fish were 40%, 0% and 0%, respectively. Dead fish and survivors at 16 and 28 d post-challenge in each group were employed for IHNV detection by RT-LAMP assay and virus isolation using BF-2 cells. IHNV from $10^{4.3}$ to $10^{6.8}\;TCID_{50}/ml$ was isolated from all the dead fish and also detected in all of the examined dead fish by RT-LAMP assay. In survivors at 16 d, 60% (3/5 fish, $10^{2.8}-10^{5.05}\;TCID_{50}/ml$), 20% (1/5 fish, $10^{1.05}\;TCID_{50}/ml$) and 60% (3/5 fish, $10^{1.05}-10^{4.8}\;TCID_{50}/ml$) were found to be IHNV-positive by virus isolation in fish challenged with IHNV at $10^{6.5}\;TCID_{50}$/fish, $10^{5.5}\;TCID_{50}$/fish and $10^{4.5}\;TCID_{50}$/fish, respectively, while 20% (1/5 fish), 0% (0/5 fish) and 20% (1/5 fish) were IHNV-positive by RT-LAMP assay. No IHNV was detected in the survivors at 28 d and control fish. These results indicate that the RT-LAMP assay is useful for detection of IHNV in diseased fish although it is not enough to monitor virus in IHNV-survivors.

• Journal of Microbiology
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• v.34 no.3
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• pp.253-269
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• 1996

Infection of fish cells with IHNV resulted in gradual increase in cytosolic free Ca$\^$2+/ concentration ([Ca$\^$2+/)] in CHSE, gradual decrease in [Ca$\^$2+/] in FHM, and no significant change in RTG cells. The degree of [Ca$\^$2+/] increase or decrease was dependent on the amount of infectious virus, and these [Ca$\^$2+/] variations were maximal at 16 hours after virus infection (p. i.) in both cell lines. When the fish cells were infected with inactivated IHNV, evident variation in [Ca$\^$2+/] was not observed. Thus, infectivity of IHNV appears to correlate with changes in [Ca$\^$2+/] in virus-infected cells. These IHNV-induced [Ca$\^$2+/] changes were partially blocked by cycloheximide, but not affected by cordycepin. It seems to be that virus-induced Ca$\^$2+/ variations were more related with protein synthesis than RNA synthesis. Various Ca$\^$2+/ related drugs were used in search for the mechanisms of the [Ca$\^$2+/], changes following IHNV infection of CHSE cells. Decreasing extracellular Ca$\^$2+/ concentration or blocking Ca$\^$2+/ influx from extracellular media inhibited the IHNV-induced increase in [Ca$\^$2+/], in CHSE cells. Similar results were obtained with intracellular Ca$\^$2+/ sources are important in IHNV-induced [Ca$\^$2+/] increase in CHSE cells.

• Journal of fish pathology
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• v.25 no.3
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• pp.143-150
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• 2012

Infectious haematopoietic necrosis virus (IHNV) is an important fish pathogen that infects both wild and cultured salmonids. Since the first isolation of IHNV from rainbow trout and masu salmon in 1991, a series of IHN disease outbreak has been reported in Korea. In 2011, we isolated two IHNV isolates from rainbow trout cultured in Korea. The full open-reading frame (ORF) encoding the glycoprotein (G) of them were sequenced and the amino acid sequences were phylogenetically analyzed. Phylogenetic analysis of the G revealed that both IHNV isolates were grouped into an Asian genogroup containing Korean IHNV isolates and Japanese IHNV isolates. However, based on their sequence variation, they were divided into different subgroup. While one isolate was similar to other Korean isolates, the other isolate showed a high level of similarity with Japanese isolates, suggesting the possibility of influx of new IHNV strain into Korea.

• Korean Journal of Microbiology
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• v.34 no.1_2
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• pp.64-68
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• 1998

In order to identify the characteristics of a Korean isol ate of infectious hematopoietic necrosis virus(IHNV), IHNV-PRT, we have cloned and analyzed cDNAs coding for matrix protein M1 and M2 of the IHNV-PRT. The Ml gene contained 693 bp open reading frame and encoded a protein of 230 amino acids with a molecular weight of 25.9 kDa. The M2 gene had 588 bp open reading frame, encoding a protein of 195 amino acids with a molecular weight of 21.9 kDa. On the deduced amino-acid sequences, M1 and M2 of the IHNV-PRT were found to be 92-93% (M1) and 97% (M2) identical to those of foreign isolates of IHNV. These results indicate that M genes of the IHNV are highly conserved among different strains of IHNV.