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Comparative transcriptome analysis reveals the role of p53 signalling pathway during red-spotted grouper nervous necrosis virus infection in Lateolabrax japonicus brain cells.

ABSTRACT: Nervous necrosis virus (NNV) is one of the fish pathogens that have caused mass mortalities of many marine and freshwater fishes in the world. To better comprehend the molecular immune mechanism of sea perch (Lateolabrax japonicus) against NNV infection, the comparative transcriptome analysis of red-spotted grouper nervous necrosis virus (RGNNV)-infected or mock-infected L. japonicus brain (LJB) cells was performed via RNA sequencing technology. Here, 1,969 up-regulated genes and 9,858 down-regulated genes, which were widely implicated in immune response pathways, were identified. Furthermore, we confirmed that p53 signalling pathway was repressed at 48 hr post-RGNNV infection, as indicated by up-regulation of Mdm2 and down-regulation of p53 and its downstream target genes, including Bax, Casp8 and CytC. Overexpression of L. japonicus p53 (Ljp53) significantly inhibited RGNNV replication and up-regulated the expression of apoptosis-related genes, whereas the down-regulation caused by pifithrin-? led to the opposite effect, suggesting Ljp53 might promote cell apoptosis to repress virus replication. Luciferase assay indicated that Ljp53 could enhance the promoter activities of zebrafish interferon (IFN)1, indicating that Ljp53 could exert its anti-RGNNV activities by enforcing the type I IFN response. This study revealed the potential antiviral role of p53 during NNV infection.

SUBMITTER: Xiang Y

PROVIDER: S-EPMC7166548 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Comparative transcriptome analysis reveals the role of p53 signalling pathway during red-spotted grouper nervous necrosis virus infection in Lateolabrax japonicus brain cells.

Xiang Yangxi Y Jia Peng P Liu Wei W Yi Meisheng M Jia Kuntong K

Journal of fish diseases 20190118 4

Nervous necrosis virus (NNV) is one of the fish pathogens that have caused mass mortalities of many marine and freshwater fishes in the world. To better comprehend the molecular immune mechanism of sea perch (Lateolabrax japonicus) against NNV infection, the comparative transcriptome analysis of red-spotted grouper nervous necrosis virus (RGNNV)-infected or mock-infected L. japonicus brain (LJB) cells was performed via RNA sequencing technology. Here, 1,969 up-regulated genes and 9,858 down-regu ...[more]

PMID: 30659619

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Project description:Nervous necrosis virus, NNV, is a neurotropic virus that causes viral nervous necrosis disease in a wide range of fish species, including European sea bass (Dicentrarchus labrax). NNV has a bisegmented (+) ssRNA genome consisting of RNA1, which encodes the RNA polymerase, and RNA2, encoding the capsid protein. The most prevalent NNV species in sea bass is red-spotted grouper nervous necrosis virus (RGNNV), causing high mortality in larvae and juveniles. Reverse genetics studies have associated amino acid 270 of the RGNNV capsid protein with RGNNV virulence in sea bass. NNV infection generates quasispecies and reassortants able to adapt to various selective pressures, such as host immune response or switching between host species. To better understand the variability of RGNNV populations and their association with RGNNV virulence, sea bass specimens were infected with two RGNNV recombinant viruses, a wild-type, rDl956, highly virulent to sea bass, and a single-mutant virus, Mut270Dl965, less virulent to this host. Both viral genome segments were quantified in brain by RT-qPCR, and genetic variability of whole-genome quasispecies was studied by Next Generation Sequencing (NGS). Copies of RNA1 and RNA2 in brains of fish infected with the low virulent virus were 1,000-fold lower than those in brains of fish infected with the virulent virus. In addition, differences between the two experimental groups in the Ts/Tv ratio, recombination frequency and genetic heterogeneity of the mutant spectra in the RNA2 segment were found. These results show that the entire quasispecies of a bisegmented RNA virus changes as a consequence of a single point mutation in the consensus sequence of one of its segments. Sea bream (Sparus aurata) is an asymptomatic carrier for RGNNV, thus rDl965 is considered a low-virulence isolate in this species. To assess whether the quasispecies characteristics of rDl965 were conserved in another host showing different susceptibility, juvenile sea bream were infected with rDl965 and analyzed as above described. Interestingly, both viral load and genetic variability of rDl965 in seabream were similar to those of Mut270Dl965 in sea bass. This result suggests that the genetic variability and evolution of RGNNV mutant spectra may be associated with its virulence.

Project description: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 × 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.

Dataset Information

Comparative transcriptome analysis reveals the role of p53 signalling pathway during red-spotted grouper nervous necrosis virus infection in Lateolabrax japonicus brain cells.

Publications

Comparative transcriptome analysis reveals the role of p53 signalling pathway during red-spotted grouper nervous necrosis virus infection in Lateolabrax japonicus brain cells.

Similar Datasets

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