Search Results (19)

Peptides designed to interfere with specific steps of viral infection mechanisms have shown promising antiviral potential. In this study, we investigated the ability of a synthetic peptide (peptide 303), derived from the fusion protein sequence of the Infectious Salmon Anemia Virus (ISAV), to inhibit membrane fusion mediated by the ISAV fusion peptide (ISAV-FP1). To assess this, we employed a model membrane system consisting of large unilamellar vesicles (LUVs) composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), dipalmitoylphosphatidylcholine (DPPC), and cholesterol. Membrane fusion kinetics were monitored via R18 fluorescence dequenching. Additionally, the interaction of peptide 303 with lipid membranes was evaluated using fluorescence anisotropy measurements. The potential direct interaction between peptide 303 and ISAV-FP1 was further examined through Förster Resonance Energy Transfer (FRET) assays. Our results demonstrate that peptide 303 effectively inhibits ISAV-FP1-mediated membrane fusion. Furthermore, peptide 303 was shown to interact with lipid bilayers and with ISAV-FP1 itself. These findings suggest a dual inhibitory mechanism in which peptide 303 both prevents ISAV-FP1 binding to the membrane and directly interacts with the fusion peptide, thereby disrupting its fusogenic activity. Full article

Infectious salmon anemia virus (ISAV) is an important pathogen in global Atlantic salmon (Salmo salar L.) aquaculture. The existence of both non-pathogenic (ISAV-HPR0) and pathogenic (HPR-deleted ISAV) forms of the virus impacts hatchery management. In November 2016, fish tested positive for ISAV-HPR0 at the National Cold Water Marine Aquaculture Center in Maine. A cohort exposed to the fish testing positive for ISAV were lethally sampled over a 7-month period (February–August 2017). No positive samples were detected during this time. Additional testing aimed to determine the extent of the ISAV infections in the facility’s fish and to investigate the water sources as potential virus entry points. Fish testing was designed to detect 2% pathogen prevalence with 95% confidence (assuming diagnostic sensitivity of 85%). Over a three-year period, ISAV-HPR0 was detected in spawning fish annually and once in smolts. Repeat testing of smolts from the affected tank three weeks later failed to detect ISAV-HPR0. Over a one-year period of weekly or biweekly evaluation of the incoming water sources, ISAV was never detected. These findings suggest that ISAV-HPR0 infections in monitored hatchery populations can evade detection and that episodes of high prevalence of ISAV-HPR0 associated with spawning can be highly transient. In both cases, conventional surveillance based on recurrent testing of healthy populations may provide only a very limited indication of the HPR0 status. Instead, targeting surveillance to periods of physiological stress, such as spawning and smoltification, and adjusting the sample sizes to account for a related surge in prevalence, should enhance the detection capacity in hatchery settings while also reducing testing costs. Full article

The potential for infectious salmon anemia virus (ISAV)—an internationally regulated pathogen of salmon—to transmit vertically from parent to offspring is currently unclear. While the highly virulent ISAV phenotype known as ISAV-HPRΔ has been observed intra-ova, evidence for vertical transmission of the avirulent ISAV phenotype known as ISAV-HPR0 is lacking. In this study, we identified ISAV-HPR0-infected Atlantic salmon broodstock during spawning within a government research recirculating aquaculture facility using qPCR. Eggs and milt from infected brood were used to initiate 16 unique family dam-sire crosses from which 29–60 fertilized eggs per cross were screened for ISAV using qPCR (limit of detection ~100 virus genome copies/egg). A portion of eggs (~300) from one family cross was hatched and further reared in biosecure containment and periodically screened for ISAV by gill clipping over a 2-year period. ISAV was not detected in any of the 781 eggs screened from 16 family crosses generated by infected brood, nor in 870 gill clips periodically sampled from the single-family cohort raised for 2 years in biocontainment. Based on these findings, we conclude that ISAV-HPR0 has a limited likelihood for vertical parent-to-offspring transmission in cultured Atlantic salmon. Full article

This article proposes a new paradigm, Sino-American film, that is centered on Chinese language in American films. Sino-American films comprise two generations. The First Generation includes Pushing Hands (1993), Take Out (2004), and Saving Face (2004) and is characterized by independent production, limited distribution, and creation during a period when Asian Americans were rarely represented on film. The Second Generation includes The Farewell (2019), Tigertail (2019), Shang-Chi and the Legend of Ten Rings (2021), and Everything Everywhere All at Once (2022) and is characterized by a Hollywood production model, widespread distribution across streaming services, and creation during a period of growing Asian American cultural representation. Sino-American films negotiate both Chinese-language film and Hollywood by focusing on overlooked characters— Chinese-language-speaking Americans. This article contributes to conversations in Chinese film studies and Asian American studies by bringing Asian American film into exchanges with three Chinese film studies paradigms: transnational cinema, Chinese-language film, and Sinophone film. This cross pollination uncovers new areas for further study. Sino-American film demonstrates the importance of Sino-American language, ethnicity, and culture within the subsuming category of Asian American film. Furthermore, pairing Sino-American films with Chinese film studies uncovers a new category of Chinese-language film outside assumed contexts and paradigms. Full article

Viral infections are still a major concern for the aquaculture industry. For salmonid fish, even though breeding strategies and vaccine development have reduced disease outbreaks, viral diseases remain among the main challenges having a negative impact on the welfare of fish and causing massive economic losses for the industry. The main entry port for viruses into the fish is through mucosal surfaces including that of the gastrointestinal tract. The contradictory functions of this surface, both creating a barrier towards the external environment and at the same time being responsible for the uptake of nutrients and ion/water regulation make it particularly vulnerable. The connection between dietary components and viral infections in fish has been poorly investigated and until now, a fish intestinal in vitro model to investigate virus–host interactions has been lacking. Here, we established the permissiveness of the rainbow trout intestinal cell line RTgutGC towards the important salmonid viruses—infectious pancreatic necrosis virus (IPNV), salmonid alphavirus (subtype 3, SAV3) and infectious salmon anemia virus (ISAV)—and explored the infection mechanisms of the three different viruses in these cells at different virus to cell ratios. Cytopathic effect (CPE), virus replication in the RTgutGC cells, antiviral cell responses and viral effects on the barrier permeability of polarized cells were investigated. We found that all virus species infected and replicated in RTgutGC cells, although with different replication kinetics and ability to induce CPE and host responses. The onset and progression of CPE was more rapid at high multiplicity of infection (MOI) for IPNV and SAV3 while the opposite was true of ISAV. A positive correlation between the MOI used and the induction of antiviral responses was observed for IPNV while a negative correlation was detected for SAV3. Viral infections compromised barrier integrity at early time points prior to observations of CPE microscopically. Further, the replication of IPNV and ISAV had a more pronounced effect on barrier function than SAV3. The in vitro infection model established herein can thus provide a novel tool to generate knowledge about the infection pathways and mechanisms used to surpass the intestinal epithelium in salmonid fish, and to study how a virus can potentially compromise gut epithelial barrier functions. Full article

Infectious salmon anemia virus (ISAV) is the etiological agent of infectious salmon anemia. It belongs to the genus isavirus, one of the genera of the Orthomyxoviridae family, as does Influenzavirus A. The ISAV genome comprises eight negative-sense single-stranded RNA segments that code for at least 10 proteins. Although some ISAV strains can reach 100% mortality rates, the factors that determine isavirus infectivity remain unknown. However, some studies suggest that segments 5 and 6 are responsible for the different degrees of virulence and infectivity among ISAV subtypes, unlike the influenza A virus, where most segments are involved in the virus infectivity. In this work, synthetic reassortant viruses for the eight segments of ISAV were generated by reverse genetics, combining a highly virulent virus, ISAV 752_09 (HPR7b), and an avirulent strain, SK779/06 (HPR0). We characterized the rescued viruses and their capacity to replicate and infect different cell lines, produce plaques in ASK cells, and their ability to induce and modulate the cellular immune response in vitro. Our results show that the majority of ISAV segments are involved in at least one of the analyzed characteristics, segment 5 being one of the most important, allowing HPR0 viruses, among other things, to produce plaques and replicate in CHSE-214 cells. We determined that segments 5 and 6 participate in different stages of the viral cycle, and their compatibility is critical for viral infection. Additionally, we demonstrated that segment 2 can modulate the cellular immune response. Our results indicate a high degree of genetic compatibility between the genomic segments of HPR7b and HPR0, representing a latent risk of reassortant that would give rise to a new virus with an unknown phenotype. Full article

Infectious salmon anaemia virus (ISAV) binds circulating Atlantic salmon erythrocytes, but the relevance of this interaction for the course of infection and development of disease remains unclear. We here characterise ISAV-erythrocyte interactions in experimentally infected Atlantic salmon and show that ISAV-binding to erythrocytes is common and precedes the development of disease. Viral RNA and infective particles were enriched in the cellular fraction of blood. While erythrocyte-associated ISAV remained infectious, erythrocytes dose-dependently limited the infection of cultured cells. Surprisingly, immunostaining of blood smears revealed expression of ISAV proteins in a small fraction of erythrocytes in one of the examined trials, confirming that ISAV can be internalised in this cell type and engage the cellular machinery in transcription and translation. However, viral protein expression in erythrocytes was rare and not required for development of disease and mortality. Furthermore, active transcription of ISAV mRNA was higher in tissues than in blood, supporting the assumption that ISAV replication predominantly takes place in endothelial cells. In conclusion, Atlantic salmon erythrocytes bind ISAV and sequester infective virus particles during infection, but do not appear to significantly contribute to ISAV replication. We discuss the implications of our findings for infection dynamics and pathogenesis of infectious salmon anaemia. Full article

The nonvirulent infectious salmon anaemia virus (ISAV-HPR0) is the putative progenitor for virulent-ISAV, and a potential risk factor for the development of infectious salmon anaemia (ISA). Understanding the transmission dynamics of ISAV-HPR0 is fundamental to proper management and mitigation strategies. Here, we demonstrate that ISAV-HPR0 causes prevalent and transient infections in all three production stages of Atlantic salmon in the Faroe Islands. Phylogenetic analysis of the haemagglutinin-esterase gene from 247 salmon showed a clear geographical structuring into two significantly distinct HPR0-subgroups, which were designated G2 and G4. Whereas G2 and G4 co-circulated in marine farms, Faroese broodfish were predominantly infected by G2, and smolt were predominantly infected by G4. This infection pattern was confirmed by our G2- and G4-specific RT-qPCR assays. Moreover, the HPR0 variants detected in Icelandic and Norwegian broodfish were never detected in the Faroe Islands, despite the extensive import of ova from both countries. Accordingly, the vertical transmission of HPR0 from broodfish to progeny is uncommon. Phylogenetic and statistical analysis suggest that HPR0 persists in the smolt farms as “house-strains”, and that new HPR0 variants are occasionally introduced from the marine environment, probably by HPR0-contaminated sea-spray. Thus, high biosecurity—including water and air intake—is required to avoid the introduction of pathogens to the smolt farms. Full article

Immersion and intraperitoneal injection are the two most common methods used for the vaccination of fish. Because both methods require that fish are handled and thereby stressed, oral administration of vaccines as feed supplements is desirable. In addition, in terms of revaccination (boosting) of adult fish held in net pens, oral administration of vaccines is probably the only feasible method to obtain proper protection against diseases over long periods of time. Oral vaccination is considered a suitable method for mass immunization of large and stress-sensitive fish populations. Moreover, oral vaccines may preferably induce mucosal immunity, which is especially important to fish. Experimental oral vaccine formulations include both non-encapsulated and encapsulated antigens, viruses and bacteria. To develop an effective oral vaccine, the desired antigens must be protected against the harsh environments in the stomach and gut so they can remain intact when they reach the lower gut/intestine where they normally are absorbed and transported to immune cells. The most commonly used encapsulation method is the use of alginate microspheres that can effectively deliver vaccines to the intestine without degradation. Other encapsulation methods include chitosan encapsulation, poly D,L-lactide-co-glycolic acid and liposome encapsulation. Only a few commercial oral vaccines are available on the market, including those against infectious pancreatic necrosis virus (IPNV), Spring viremia carp virus (SVCV), infectious salmon anaemia virus (ISAV) and Piscirickettsia salmonis. This review highlights recent developments of oral vaccination in teleost fish. Full article

Infectious salmon anemia virus (ISAV) infection is currently detected by fish sampling for PCR and immunohistochemistry analysis. As an alternative to sampling fish, we evaluated two different membrane filters in combination with four buffers for elution, concentration, and detection of ISAV in seawater, during a bath challenge of Atlantic salmon (Salmo salar L.) post-smolts with high and low concentrations of ISAV. Transmission of ISAV in the bath challenge was confirmed by a high mortality, clinical signs associated with ISA disease, and detection of ISAV RNA in organ tissues and seawater samples. The electronegatively charged filter, combined with lysis buffer, gave significantly higher ISAV RNA detection by droplet digital PCR from seawater (5.6 × 10⁴ ISAV RNA copies/L; p < 0.001). Viral shedding in seawater was first detected at two days post-challenge and peaked on day 11 post-challenge, one day before mortalities started in fish challenged with high dose ISAV, demonstrating that a large viral shedding event occurs before death. These data provide important information for ISAV shedding that is relevant for the development of improved surveillance tools based on water samples, transmission models, and management of ISA. Full article

Agriculture’s goal to meet the needs of the increasing world population while reducing the environmental impacts of nitrogen (N) fertilizer use without compromising output has proven to be a challenge. Manure and composts have displayed the potential to increase soil fertility. However, their potential effects on nitrous oxide (N₂O) and methane (CH₄) emissions have not been properly understood. Using field-scaled lysimeter experiments, we conducted a one-year study to investigate N₂O and CH₄ emissions, their combined global warming potential (GWP: N₂O + CH₄) and yield-scaled GWP in a wheat-maize system. One control and six different organic fertilizer treatments receiving different types but equal amounts of N fertilization were used: synthetic N fertilizer (NPK), 30% pig manure + 70% synthetic N fertilizer (PM30), 50% pig manure + 50% synthetic N fertilizer (PM50), 70% pig manure + 30% synthetic N fertilizer (PM70), 100% pig manure (PM100), 50% cow manure-crop residue compost + 50% synthetic N fertilizer (CMRC), and 50% pig manure-crop residue compost + 50% synthetic N fertilizer (PMRC). Seasonal cumulative N₂O emissions ranged from 0.39 kg N ha⁻¹ for the PMRC treatment to 0.93 kg N ha⁻¹ for the NPK treatment. Similar CH₄ uptakes were recorded across all treatments, with values ranging from −0.68 kg C ha⁻¹ for the PM50 treatment to −0.52 kg C ha⁻¹ for the PM30 treatment. Compared to the NPK treatment, all the organic-amended treatments significantly decreased N₂O emission by 32–58% and GWP by 30–61%. However, among the manure-amended treatments, only treatments that consisted of inorganic N with lower or equal proportions of organic manure N treatments were found to reduce N₂O emissions while maintaining crop yields at high levels. Moreover, of all the organic-amended treatments, PMRC had the lowest yield-scaled GWP, owing to its ability to significantly reduce N₂O emissions while maintaining high crop yields, highlighting it as the most suitable organic fertilization treatment in Sichuan basin wheat-maize systems. Full article

Viral infections in salmonids represent an ongoing challenge for the aquaculture industry. Two RNA viruses, the infectious pancreatic necrosis virus (IPNV) and the infectious salmon anemia virus (ISAV), have become a latent risk without healing therapies available for either. In this context, antiviral peptides emerge as effective and relatively safe therapeutic molecules. Based on in silico analysis of VP2 protein from IPNV and the RNA-dependent RNA polymerase from ISAV, a set of peptides was designed and were chemically synthesized to block selected key events in their corresponding infectivity processes. The peptides were tested in fish cell lines in vitro, and four were selected for decreasing the viral load: peptide GIM182 for IPNV, and peptides GIM535, GIM538 and GIM539 for ISAV. In vivo tests with the IPNV GIM 182 peptide were carried out using Salmo salar fish, showing a significant decrease of viral load, and proving the safety of the peptide for fish. The results indicate that the use of peptides as antiviral agents in disease control might be a viable alternative to explore in aquaculture. Full article

Characterizing greenhouse gas (GHG) emissions and global warming potential (GWP) has become a key step in the estimation of atmospheric GHG concentrations and their potential mitigation by cropland management. However, the impacts of organic amendments on GHG, GWP, and yield-scaled GWP on cropland have not been well documented. Here, we investigate four amendment treatments (no amendment, mineral fertilizers, and pig slurry or crop residue combined with mineral fertilizers) during a two-year field experiment in rain-fed wheat-maize cropping systems. The results show that the average annual cumulative methane (CH₄) flux ranged from −2.60 to −2.97 kg·C·ha⁻¹ while nitrous oxide (N₂O) flux ranged from 0.44 to 4.58 kg·N·ha⁻¹ across all four treatments. N₂O emissions were significantly correlated with soil inorganic nitrogen (i.e., NH₄⁺-N and NO₃⁻-N), and soil dissolved organic carbon (DOC) during both the winter wheat and summer maize seasons. On average, organic amendments combined with mineral fertilizers increased the annual GWP by 26–74% and yield-scaled GWP by 19–71% compared to those under only mineral fertilizers application. This study indicates that the fertilization strategy for Eutric Regosols can shift from only mineral fertilizers to organic amendments combined with mineral fertilizers, which can help mitigate GHG emissions and GWP while maintaining crop yields. Full article

Infectious salmon anemia virus (ISAv) is a pathogen of high economic importance worldwide; it produces a highly fatal clinical symptomatology called infectious salmon anemia (ISA), which is one of the main causes of economic loss in Chilean aquaculture, specifically in Chilean salmon, being responsible for a mortality rate greater than 80% when outbreaks of this pathogen occur in fish farms. ISAv dramatically increases levels of reactive oxygen species (ROS) by increasing the activity of the p38MAPK protein, which activates p47phox, by phosphorylation, allowing its binding to the membrane subunits of the NADPH oxidase complex, which is an important positive regulator of ROS levels in cells. Further, it is known that oxidative stress is able to regulate the SUMOylation machinery, producing an increase in SUMOylated proteins. Together with this background and various bioinformatic analyses, it was found that the ISAv nucleoprotein (NP) has a highly conserved capacity for SUMOylation, and this protein alone is capable of causing strong oxidative stress in transfected cells and is therefore able to regulate the SUMOylation machinery. Immunoprecipitation assays confirmed the bioinformatic analyses, where NP was seen to be SUMOylated, and this signal decreased considerably when cells were treated with a p38MAPK inhibitor. Together with this, the number of copies of NP and the viability in cells infected with ISAv were also evaluated, where it was observed that there was a strong increase in the number of copies of NP and a marked decrease in cell viability, this being in contrast to when, in addition to the infection, the cells were treated with a natural product “maqui” (A. chilensis), which, due to its high content of polyphenolic compounds, has been shown to have a high antioxidant capacity, greatly reducing the number of copies of NP and the percentage of mortality compared to cells that are only infected with ISAv. Full article

The infectious salmon anemia virus (ISAV), etiological agent of the disease by the same name, causes major losses to the salmon industry. Classified as a member of the Orthomyxoviridae family, ISAV is characterized by the presence of two surface glycoproteins termed hemagglutinin esterase (HE) and fusion protein (F), both of them directly involved in the initial interaction of the virus with the target cell. HE mediates receptor binding and destruction, while F promotes the fusion process of the viral and cell membranes. The carboxy-terminal end of F (F₂) possesses canonical structural characteristics of a type I fusion protein, while no functional properties have been proposed for the amino-terminal (F₁) region. In this report, based on in silico modeling, we propose a tertiary structure for the F₁ region, which resembles a sialic acid binding domain. Furthermore, using recombinant forms of both HE and F proteins and an in vitro model system, we demonstrate the interaction of F with a cell receptor, the hydrolysis of this receptor by the HE esterase, and a crucial role for F₁ in the fusion mechanism. Our interpretation is that binding of F to its cell receptor is fundamental for membrane fusion and that the esterase in HE modulates this interaction. Full article