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Sandra Souto Jos G. Olveira Esther García‐Rosado Carlos P. Dopazo Isabel Bandín 《Journal of fish diseases》2019,42(2):221-227
Betanodavirus reassortant strains (RGNNV/SJNNV) isolated from Senegalese sole harbour an SJNNV capsid featuring several changes with respect to the SJNNV‐type strain, sharing three hallmark substitutions. Here, we have employed recombinant strains harbouring mutations in these positions (r20 and r20 + 247 + 270) and have demonstrated that the three substitutions affect different steps of the viral replication process. Adsorption ability and efficiency of viral attachment were only affected by substitutions in the C‐terminal side of the capsid. However, the concurrent mutation in the N‐terminal side seems to slightly decrease these properties, suggesting that this region could also be involved in viral binding. Differences in the intracellular and extracellular production of the mutant strains suggest that both the C‐terminal and N‐terminal regions of the capsid protein may be involved in the particle budding. Furthermore, viral replication in sole brain tissue of the mutant strains, and especially double‐ and triple‐mutant strains, is clearly delayed with respect to the wt strain. These data support previous findings indicating that the C‐terminal side plays a role in virulence because of a slower spread in the fish host brain and suggest that the concurrent participation of the N‐terminal side is also important for viral replication in vivo. 相似文献
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An aquabirnavirus (ABV) and a formalin-inactivated betanodavirus [redspotted grouper nervous necrosis virus (RGNNV)] were investigated for their potential to prevent RGNNV-induced viral nervous necrosis (VNN) in the sevenband grouper, Epinephelus septemfasciatus (Thunberg). Three groups of fish were injected intramuscularly with ABV, intraperitoneally with inactivated RGNNV (iRGNNV) or with both ABV and iRGNNV. At 3, 7, 14, 21 and 28 days post-injection (p.i.), fish were challenged by intramuscular injection of RGNNV. Control fish, which received neither ABV nor iRGNNV, showed high mortalities in all RGNNV challenges. Fish that received only ABV exhibited relative percent survival (RPS) of >60 against RGNNV challenges at 3, 7, 14 and 21 days p.i., but not at 28 days p.i., while fish that received only iRGNNV showed significantly higher protection against RGNNV challenges only at 21 and 28 days p.i. In contrast, fish that received both ABV and iRGNNV showed 60 or higher RPS against all RGNNV challenges. Fish inoculated with iRGNNV with or without ABV exhibited similar high titres of neutralizing antibodies to RGNNV at 14, 21 and 28 days p.i. These results indicate that combined inoculation with iRGNNV and ABV conferred both rapid non-specific and delayed specific protection against VNN. 相似文献
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N Vendramin A Toffan M Mancin E Cappellozza V Panzarin G Bovo G Cattoli I Capua C Terregino 《Journal of fish diseases》2014,37(4):371-383
Viral encephalopathy and retinopathy (VER), otherwise known as viral nervous necrosis (VNN), is a severe pathological condition caused by RNA viruses belonging to the Nodaviridae family, genus Betanodavirus. The disease, described in more than 50 fish species worldwide, is considered as the most serious viral threat affecting marine farmed species in the Mediterranean region, thus representing one of the bottlenecks for further development of the aquaculture industry. To date, four different genotypes have been identified, namely red‐spotted grouper nervous necrosis virus (RGNNV), striped jack nervous necrosis virus (SJNNV), tiger puffer nervous necrosis virus and barfin flounder nervous necrosis virus, with the RGNNV genotype appearing as the most widespread in the Mediterranean region, although SJNNV‐type strains and reassortant viruses have also been reported. The existence of these genetically different strains could be the reason for the differences in mortality observed in the field. However, very little experimental data are available on the pathogenicity of these viruses in farmed fish. Therefore, in this study, the pathogenicity of 10 isolates has been assessed with an in vivo trial. The investigation was conducted using the European sea bass, the first target fish species for the disease in the Mediterranean basin. Naive fish were challenged by immersion and clinical signs and mortality were recorded for 68 days; furthermore, samples collected at selected time points were analysed to evaluate the development of the infection. Finally, survivors were weighed to estimate the growth reduction. The statistically supported results obtained in this study demonstrated different pathogenicity patterns, underlined the potential risk represented by different strains in the transmission of the infection to highly susceptible species and highlighted the indirect damage caused by a clinical outbreak of VER/VNN. 相似文献
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Costa JZ Adams A Bron JE Thompson KD Starkey WG Richards RH 《Journal of fish diseases》2007,30(7):419-426
The pepscan procedure was used to identify betanodavirus B-cell epitopes recognized by neutralizing mouse monoclonal antibodies (MAbs) and serum samples obtained from sea bass, Dicentrarchus labrax, naturally infected with betanodavirus. Pepscan was performed with a panel of thirty-four 12-mer synthetic peptides that mimicked the entire betanodavirus capsid protein. Sea bass serum samples reacted strongly with three regions of the capsid protein comprising amino acid residues 1-32, 91-162 and 181-212. The latter region was also recognized by neutralizing MAbs and coincided with a region of high antigenic propensity identified by an antigen prediction algorithm. These data suggest that a region of the betanodavirus capsid protein spanning amino acid residues 181-212 may represent a neutralization domain that could potentially be used to inform the development of nodavirus vaccines and immunodiagnostic reagents. 相似文献