Vaccination against Diseases Caused by Betanodavirus

Patel, Sonal; Nerland, Audun Helge

doi:10.1002/9781118806913.ch29

Cited by 4 publications

(3 citation statements)

References 46 publications

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“…Other risk factors associated with VNN are fish age and fish size. VNN is frequently detected in small fish, although larger fish can be infected by its causative agent under certain circumstances, and this varies among fish species [8,9].…”

Section: Introductionmentioning

confidence: 99%

Risk factors associated with viral nervous necrosis in hybrid groupers in Malaysia and the high similarity of its causative agent nervous necrosis virus to reassortant red-spotted grouper nervous necrosis virus/striped jack nervous necrosis virus strains

Ariff

Abdullah²,

Azmai

et al. 2019

Vet World

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Background and Aim: Viral nervous necrosis (VNN) is a serious disease of several marine fish species. VNN causes 100% mortality in the larval stages, while lower losses have been reported in juvenile and adult fish. This study aimed to detect the occurrence of VNN while identifying its associated risk factors and the genotypes of its causative agent in a hybrid grouper hatchery in Malaysia. Materials and Methods: A batch of newly hatched hybrid grouper fry (Epinephelus fuscoguttatus X Epinephelus lanceolatus) were followed from the larval stage to market size. Samples of the hybrid groupers, water, live feed, and artificial fish pellets were collected periodically from day 0 to 180 in the hybrid grouper hatchery. Reverse transcription-polymerase chain reaction (RT-PCR) and nested PCR amplifications were carried out on VNN-related sequences. The phylogenetic tree including the sampled causative agent of VNN was inferred from the coat protein genes from all known Betanodavirus species using Molecular Evolutionary Genetics Analysis (MEGA). Pearson's correlation coefficient values were calculated to determine the strength of the correlation between the presence of VNN in hybrid grouper samples and its associated risk factors. Results: A total of 113 out of 146 pooled and individual samples, including hybrid grouper, water, and artificial fish pellet samples, demonstrated positive results in tests for the presence of VNN-associated viruses. The clinical signs of infection observed in the samples included darkened skin, deformation of the backbone, abdominal distension, skin lesions, and fin erosion. VNN was present throughout the life stages of the hybrid groupers, with the first detection occurring at day 10. VNN-associated risk factors included water temperature, dissolved oxygen content, salinity, ammonia level, fish size (adults more at risk than younger stages), and life stage (age). Detection of VNN-associated viruses in water samples demonstrated evidence of horizontal transmission of the disease. All the nucleotide sequences found in this study had high nucleotide identities of 88% to 100% to each other, striped jack nervous necrosis virus (SJNNV), and the reassortant strain red-spotted grouper NNV/SJNNV (RGNNV/SJNNV) isolate 430.2004 (GenBank accession number JN189932.1) (n=26). The phylogenetic analysis showed that quasispecies was present in each VNN-causing virus-positive sample, which differed based on the type of sample and life stage. Conclusion: This study was the first to confirm the existence of a reassortant strain (RGNNV/SJNNV) in hybrid groupers from Malaysia and Southeast Asia. However, the association between the mode of transmission and the risk factors of this virus needs to be investigated further to understand the evolution and potential new host species of the reassortant strain. Keywords: epidemiology, quasispecies, reassortant, red-spotted grouper nervous necrosis virus-striped jack nervous necrosis virus, viral nervous necrosis.

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Section: Introductionmentioning

confidence: 99%

Risk factors associated with viral nervous necrosis in hybrid groupers in Malaysia and the high similarity of its causative agent nervous necrosis virus to reassortant red-spotted grouper nervous necrosis virus/striped jack nervous necrosis virus strains

Ariff

Abdullah²,

Azmai

et al. 2019

Vet World

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“…Nodavirus has been shown to be very stable under extreme environmental conditions [12]. Once the virus has entered a farm or rearing unit, it may be very difficult to eliminate [38]. The phylogenetic tree for NNV showed high homology (*99 % sequence identity) among members of the genus Gadus, e.g., Pacific cod, Atlantic cod and haddock, which may account for inter-species virus spread, although this may depend on species habitat and interaction.…”

Section: Nervous Necrosis Virus Infection In Pacific Codmentioning

confidence: 99%

“…This assay can help farmers select NNV-negative broodfish. In addition, we have successfully expressed the viral capsid protein as a step towards producing a protective NNV vaccine, even though immunization seems to have a limited effect [38]. Analysis of Rag1 (A) and Igl (B) expression during developmental stages in Pacific cod using A-qPCR [27] …”

Section: Nervous Necrosis Virus Infection In Pacific Codmentioning

confidence: 99%

Evidence for and characterization of nervous necrosis virus infection in Pacific cod (Gadus macrocephalus)

et al. 2015

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A mortality rate higher than 90% was observed in a larva-rearing facility for Pacific cod, Gadus macrocephalus, in China. Larvae showing clinical signs of infection were collected. Initial suspicion of nervous necrosis virus (NNV) infection was confirmed by sequencing, absolute quantification real-time PCR (A-qPCR), and electron microscopy. The nucleotide sequence of RNA2 was 1,375 bases long (GenBank no. KM576685), coding for a single ORF corresponding to the capsid protein from residues 21 to 1034. Phylogenetic analysis of the capsid protein sequence showed that PCNNV belongs to the barfin flounder NNV (BFNVV) genotype. An amino acid sequence alignment revealed 39 differences between the cold- and warm-resistant viral groups, suggesting that PCNNV evolved under temperature selection. The 3-D structure of the predicted capsid protein was modeled to identify potential epitopes, and the gene was expressed in Escherichia coli, yielding a protein with a molecular mass of 55 kDa. During PCNNV outbreaks, the viral copy number was found to reach 10(7) per ng of total RNA, which could be considered the lethal copy number of NNV in cod. The gonads, eggs, fertilized eggs and asymptomatic cod fry were all positive for PCNNV, indicating viral vertical transmission as the main source of the viral load. The amount of virus in the apparent healthy fry or survivors seemed to decrease gradually with development. These results might lead to efficient diagnostic methods to help farmers select NNV-free broodfish for cod breeding.

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An investigation on protective effects of the new killed vaccine against nervous necrosis virus (NNV) using histopathology and immunohistochemistry approach on the brain and eye tissues of Acipenser stellatus Pallas 1771

Afsharipour

Zorriehzahra

Takami

et al. 2021

Fish & Shellfish Immunology

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Vaccination against Diseases Caused by Betanodavirus

Cited by 4 publications

References 46 publications

Risk factors associated with viral nervous necrosis in hybrid groupers in Malaysia and the high similarity of its causative agent nervous necrosis virus to reassortant red-spotted grouper nervous necrosis virus/striped jack nervous necrosis virus strains

Risk factors associated with viral nervous necrosis in hybrid groupers in Malaysia and the high similarity of its causative agent nervous necrosis virus to reassortant red-spotted grouper nervous necrosis virus/striped jack nervous necrosis virus strains

Evidence for and characterization of nervous necrosis virus infection in Pacific cod (Gadus macrocephalus)

An investigation on protective effects of the new killed vaccine against nervous necrosis virus (NNV) using histopathology and immunohistochemistry approach on the brain and eye tissues of Acipenser stellatus Pallas 1771

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