Infectious Hematopoietic Necrosis Research Articles (Page 1)

A tetrazole-based immunomodulator confers mitochondrial protection and enhances host resistance against IHNV in rainbow trout.

Screening of proteins interacting with infectious hypodermal and hematopoietic necrosis virus in Pacific white shrimp Litopenaeus vannamei.

Toll-like receptors (TLRs) are a class of pattern-recognition receptors that recognize pathogen- and damage-associated molecular patterns and initiate immune responses. TLRs selectively recruit distinct adapter molecules such as the myeloid differentiation primary response protein 88 (MyD88) that mediates signaling downstream of all TLRs, with the exception of TLR3. To investigate TLR signaling pathways in fish, we engineered a knockout clonal epitheliod fish cell line, named MYD88C2, using CRISPR/Cas9-mediated genome editing to disrupt the myd88 gene. We characterized the phenotype of this cell line alongside a wild-type cell line through gene-expression profiling and reporter-gene analyses in the context of stimulation with heat-killed Vibrio anguillarum, heat-killed Escherichia coli, flagellin, zymosan, and inoculation with a panel of viruses. We demonstrate that the proinflammatory response to zymosan and flagellin, as measured through the induction of proinflammatory genes, was greatly reduced in the MYD88C2 cell line. The responsiveness to zymosan was found to be partially restored by transfecting the MYD88C2 cell line with a myd88-expression plasmid. In contrast, the loss of the myd88 gene had no impact on the cytopathic effect associated with the replication of viral haemorrhagic septicemia virus (VHSV), infectious haematopoietic necrosis virus (IHNV), infectious pancreatic necrosis virus (IPNV), spring viraemia of carp virus (SVCV) or infectious salmon anaemia virus (ISAV). These findings highlight the critical role of MyD88 in mediating specific proinflammatory responses to bacterial and fungal stimuli, while its absence has no detectable impact on viral replication or cytopathogenicity in epithelioid fish cells under the conditions tested.

Infectious hematopoietic necrosis virus (IHNV), a salmonid rhabdovirus, causes severe mortality exceeding 90% in both wild and farmed salmon and trout. Frequent outbreaks of IHNV highlight the urgent need for rapid detection methods to support effective prevention and control. This study developed a double-antibody sandwich ELISA (DAS-ELISA) targeting the nucleocapsid (N) protein of IHNV. Two peptides derived from the N protein—selected for their strong antigenicity, high level of conservation, and surface accessibility—were used as immunogens to generate two specific monoclonal antibodies. Following optimization, the DAS-ELISA was established using monoclonal antibody N-15 as the capture antibody and horseradish peroxidase (HRP)-conjugated antibody N-106 as the detection antibody. The results of this study demonstrated that DAS-ELISA exhibited high specificity for multiple IHNV strains and showed no cross-reactivity with IPNV, SVCV, or VHSV. The detection sensitivity of DAS-ELISA for IHNV was determined to be 103 TCID50/mL. Parallel analysis of 293 clinical samples using DAS-ELISA and WOAH reference method demonstrated a concordance rate of 92.83% (κ = 0.856). These results confirm that the established DAS-ELISA exhibits high sensitivity, specificity, broad-spectrum applicability, and repeatability. In conclusion, this DAS-ELISA provides a reliable and efficient tool for high-throughput early detection of IHNV infection in clinical settings.

Generation and evaluation of nanobodies specific for the proteins from infectious hypodermal and hematopoietic necrosis virus.

A novel infectious hematopoietic necrosis virus (IHNV) isolated from white-spotted charr (Salvelinus leucomaenis) is moderately virulent to rainbow trout (Oncorhynchus mykiss)

Temperature impact on replication and virulence of European infectious hematopoietic necrosis viruses

Comparative virulence and evolution analysis of infectious hematopoietic necrosis virus (IHNV) isolated from cultured Oncorhynchus mykiss in three different regions of China.

A case report about the detection of infectious hypodermal and hematopoietic necrosis virus (IHHNV) in shrimp displaying no clinical signs or histopathological lesions from farms on Colombia's north coast.

Passive eDNA sampling to monitor infectious hypodermal and haematopoietic necrosis virus (IHHNV) in pond-reared giant black tiger shrimp (Penaeus monodon) aquaculture systems

Background: Vaccination is often a highly effective approach for protecting against clinical disease and mortality caused by viruses. However, vaccine efficacy against viral transmission has rarely been assessed, which can provide vital information on the eradication efficacy and sustainability of vaccines in the field. Methods: Here, we evaluated the host mortality, shedding, and direct fish-to-fish transmission protection efficacy of three vaccine regimens (DNA, inactivated, and attenuated) against infectious hematopoietic necrosis virus (IHNV) in rainbow trout. We quantified protection against single- and mixed-genotype IHNV infections when the vaccines were delivered by intramuscular injection, intraperitoneal injection, and bath immersion, respectively, to reflect field conditions. Results: All three vaccine regimens provided significant protection against fish mortality. The DNA vaccine regimen was qualitatively the most protective and the attenuated vaccine regimen the least. However, these three vaccines provided limited protection against viral shedding. Cumulative shedding over the course of the infection was only slightly reduced compared to unvaccinated fish. There was some indication that the viral genotype fish were exposed to influenced vaccine efficacy, perhaps as a result of genetic similarity to the vaccine strain. Likewise, the DNA vaccine reduced direct transmission in fish cohabitation experiments from 100% to 50%. The inactivated and attenuated vaccine had little impact on IHNV transmission. Conclusions: Collectively, our results suggest that existing IHNV vaccines that increase host survival provide minimal virus transmission protection in rainbow trout, which is likely to limit their long-term efficacy in the field. This work contributes to a growing body of evidence that enhancement of the transmission protection of IHNV and other vaccines will likely bolster disease reduction in the field.

Many studies have demonstrated that miRNAs play a crucial role in virus-host interactions. This study aimed to investigate the antiviral effects of miR-146a in Epithelioma papulosum cyprini (EPC) cells infected with viral hemorrhagic septicemia virus (VHSV), infectious pancreatic necrosis virus (IPNV), and infectious haematopoietic necrosis virus (IHNV), which are major causes of mortality in various freshwater and marine fish worldwide. Cytopathic effects (CPE) were observed as early as 72 h post-infection in both the control group and the miR-146a inhibitor group. In contrast, CPE formation was not observed in virus-infected groups treated with the miR-146a mimic. The control and miR-146a inhibitor groups exhibited a rapid increase in viral titres after 48 h, whereas the miR-146a mimic-treated groups showed minimal viral replication at all assay time points. To further investigate the antiviral mechanism of miR-146a, we analysed the genes upregulated by miR-146a following viral stimulation. The results revealed a significant increase in the expression of genes involved in the type I interferon (IFN) response in the miR-146a mimic group. Taken together, these findings suggest that miR-146a exerts antiviral effects against VHSV, IPNV and IHNV.

mRNA vaccines have demonstrated significant potential in preventing human diseases and controlling livestock infections. However, the application of mRNA vaccines in aquaculture, especially on fish, remains limited. Infectious hematopoietic necrosis virus (IHNV) is an RNA virus that mainly affects rainbow trout (Oncorhynchus mykiss), leading to high mortality rates. In this study, we systematically engineered three UTR-optimized mRNA constructs, exhibiting comparable and sustained in vitro antigen expression. Following encapsulation, the mG1-LNP formulation, incorporating endogenous antigen-specifics, conferred robust relative protection against IHNV challenge, accompanied by enhanced levels of IgM and neutralizing antibodies. Furthermore, dose-response profiling identified 10 μg/dose as the immunologically optimized regimen, eliciting efficient immunogenicity. Moreover, biodistribution analyses revealed complete mG1-LNP clearance from injection sites and hepatic tissues by 28 dpv, confirming favorable biosafety. Collectively, our work demonstrates the successful development of mRNA-LNP vaccine against infectious IHNV in rainbow trout, providing the first empirical demonstration of mRNA-LNP vaccine efficacy in aquaculture.

ABSTRACTCarp oedema virus disease (CEVD), caused by the carp oedema virus (CEV), results in significant economic losses to the common carp and koi aquaculture industry. The CEVD symptoms resemble those of koi herpesvirus (KHV) and include lethargy, swollen gills, sunken eyes, and skin haemorrhages. Consequently, the development of efficient detection methods is imperative for the prevention and diagnosis of CEVD. In this study, we developed a quantitative real‐time PCR assay for the sensitive detection of CEV infection. Specific primers were designed based on a highly conserved region within the CEV p4a gene. The assay exhibited a sensitivity that was 100‐fold greater than that of the conventional PCR technique, with high specificity, and no observed cross‐reactivity with infectious haematopoietic necrosis virus (IHNV), infectious pancreatic necrosis virus (IPNV), spring viremia of carp virus (SVCV), salmonid alphavirus (SAV), or KHV. Inter‐ and intra‐assay experiments also confirmed the method's high repeatability. In a clinical setting, it showed higher sensitivity compared to the diagnostic methods for CEVD developed by the Center for Environment, Fisheries and Aquaculture Science (CEFAS), while also significantly reducing detection costs. Consequently, the established assay could provide robust technical support for the clinical diagnosis and epidemiological investigation of CEVD.

ABSTRACTShrimp aquaculture plays a crucial role in global food production but is increasingly threatened by viral and microsporidian pathogens such as White Spot Syndrome Virus (WSSV), Enterocytozoon hepatopenaei (EHP) and Infectious Hypodermal and Haematopoietic Necrosis Virus (IHHNV). Conventional reliance on antibiotics to combat these infections has raised serious concerns regarding antimicrobial resistance, environmental contamination and food safety. Additionally, environmental stressors such as salinity shifts and poor water quality exacerbate disease outbreaks, leading to severe production losses across Asia and Latin America. To explore eco‐friendly therapeutic alternatives, this study assessed the antiviral potential of cannabidiol (CBD), a bioactive compound extracted from Cannabis sativa seed oil, identified through GC–MS analysis. Using molecular docking techniques, we evaluated CBD's interactions with key viral proteins: VP28 of WSSV, the tubulin β‐chain of EHP and the capsid protein of IHHNV. The docking results revealed strong binding affinities of −6.61 kcal/mol (EHP), −6.72 kcal/mol (IHHNV) and −5.38 kcal/mol (WSSV), indicating stable and potentially inhibitory interactions. Structural models were retrieved from RCSB PDB and SwissModel, while ligand preparation and docking were performed using AutoDock 4.2. CBD also demonstrated favourable pharmacokinetic and safety profiles, with predictions indicating no mutagenicity, hepatotoxicity or cardiotoxicity, and acceptable drug‐likeness characteristics. Compared to other plant‐derived compounds previously tested in shrimp disease models, CBD exhibited superior binding stability, more interaction residues and better bioavailability scores. These findings highlight CBD as a promising dual‐function agent, capable of both modulating shrimp immunity and directly inhibiting key viral pathogens. These findings highlight cannabidiol (CBD) as a promising dual‐action compound, with the potential to both enhance shrimp immune responses and exert direct antiviral effects against key pathogens. This study lays a robust groundwork for future in vivo validations, formulation strategies and regulatory frameworks, ultimately supporting the development of sustainable, precision‐based aquaculture health management.

Endogenous viral elements (EVEs) serve as molecular fossils that record the ancient co-evolutionary arms race between viruses and their hosts. In this study, by analyzing 105 host crustacean genomes, we identified 252 infectious hypodermal and haematopoietic necrosis virus-derived EVEs (IHHNV-EVEs), which include 183 ancient and 6 recently inserted EVEs. These IHHNV-EVEs are widely distributed among Decapoda, Thoracica, and Isopoda, with some of them exhibiting a syntenic distribution relative toneighboringhost sequences, suggesting that the IHHNV or its ancestor are potential pathogens of these species with a long-time dynamic interaction during the evolutionary history. An expansion of IHHNV-EVEs was observed indecapodagenomes, reflecting a reinforced arm race betweendecapodaand IHHNV. Notably, we found that nearly all recent IHHNV-EVEs were laboratory contaminants, except for a single authentic integration in Penaeus monodon that persists intact across 16 samples from the 2 populations. These temporal dynamics-ancient genomic stabilization versus modern colonization activity-highlight that EVEs serve as dual archives: historical records of past conflicts and active participants in current evolutionary battles. Our findings redefine viral genomic colonization as a continuum, where ancient EVE fixation coexists with persistent integration processes, providing new insights into host-virus co-evolutionary trajectories.

A lateral flow immunochromatographic assay (LFIA) was developed for the rapid detection of infectious haematopoietic necrosis virus (IHNV, genogroups JRt-N and JRt-S) in rainbow trout (Oncorhynchus mykiss). The assay utilises the monoclonal antibody (mAb) IHNV-3, which serves as both the detector antibody in a colloidal gold-mAb conjugate and the capture antibody on the test line. The LFIA strip demonstrated a detection limit ranging from 105.05 to 105.8 TCID50/100 μL for six IHNV isolates (genogroups JRt-N and JRt-S) and showed no cross-reactivity with other fish viruses. Field validation using spleen samples from 81 IHNV-infected and 102 non-infected rainbow trout revealed a specificity of 100%, a sensitivity of 97.5%, and an overall diagnostic effectiveness of 98.9%. These results highlight the LFIA strip as a reliable tool for the rapid (within 10 min) on-site detection of IHNV in rainbow trout at aquaculture facilities.

The freshwater prawn Macrobrachium rosenbergii is widely farmed in India, and except for Macrobrachium nodavirus (MrNV), no significant pathogens infecting this species have been reported. In this perspective, a histology- and PCR-based screening of M. rosenbergii was carried out for pathogens such as hepatopancreatic parvovirus (HPV), Enterocytozoon hepatopenaei (EHP) and infectious hypodermal and haematopoietic necrosis virus (IHHNV). For this, 335 samples were collected from five locations in Kerala, Maharashtra and West Bengal, India. Fifty animals, consisting of post-larvae, sub-adults and adults, were subjected to histological analysis, and the majority of the post-larvae (from Kerala) and a few sub-adult samples (from West Bengal) showed eosinophilic to basophilic, intranuclear inclusions, typical of HPV infection. The prevalence of HPV and EHP was found to be 61.3% and 95.4%, respectively, and 56.8% of the samples displayed multiple infections. None of the samples showed the presence of IHHNV. The sequence analysis of PCR amplicons indicated 90%-93% and 100% similarity to the capsid protein gene of HPV and the spore wall protein gene of EHP, respectively. This report formed the first documentation of HPV and EHP in M. rosenbergii from India and the first report of dual infections of these pathogens in freshwater prawn.

6PPD-quinone (6PPDQ), derived from the tire-protectant6PPD reactingwith ozone, is an emerging contaminant of concern owing to its rolein coho salmon (Oncorhynchus kisutch) deaths viaurban runoff mortality syndrome (URMS). Given the impact of 6PPDQon aquatic life in urban streams, we addressed the acute toxicityof 6PPDQ exposure on coastal cutthroat trout (CCT) (Oncorhynchusclarkii clarkii), a species sympatric with coho salmon innatal watersheds. Using static exposures coupled with analytical chemistry,we determined the 24-h LC50 values for alevin (297.2 ng/L),swim-up fry (39.6 ng/L), 5-month parr (103.3 ng/L), and 13-month juveniles(185.9 ng/L)values similar to toxicity observed in coho salmon.Additionally, the 96-h LC50 (77.6 ng/L) was 2.4 times morelethal for juvenile CCT. We assessed potential effects of sublethal6PPDQ exposure on disease resistance to infectious hematopoietic necrosis(IHN), an endemic viral disease of Pacific salmon, and to swimmingperformance. Sublethal 6PPDQ (53.6 ng/L) did not affect survival ofparr exposed to IHN virus compared to virus alone. Conversely, 6PPDQexposure as low as 72.2 ng/L significantly reduced 15- and 24-monthjuvenile swimming performance, and 120.5 ng/L 6PPDQ increased bloodhematocrit. Overall, CCT are the second most sensitive species testedto date for 6PPDQ sensitivity which further emphasizes the need foridentifying alternatives to 6PPD.

Antiviral potential of the arctigenin derivative COA in reducing viral adhesion to the epithelial cell surface against IHNV infection.