Search

Grouper (Epinephelus coioides) is an important commercial maricultural fish, which suffers from nervous necrosis virus (NNV) infection. The molecular mechanisms underlying the pathogenesis of the viral infection are not clear. In this study, we combined deep RNA sequencing and label-free mass spectrum for the first time to analyze the transcriptomic and proteomic profiles in infected/dead, infected/survival (persistent), and infection-free (control)orange-spotted groupers in the larval stage. Further analyses showed that the transcriptome and proteome changed dramatically among the three distinct groups, especially differentially-expressed genes in the infected/dead and infected/survival larvae enriched for pathways related to immune response. Notably, the overlapped genes between transcriptomes and proteomes identified that genes related to collagen synthesis and adhesion molecules were enhanced in the persistent (infected/survival) stage, which might contribute to suppressing the acute and lethal immune responses upon NNV infection. These transcriptomic and proteomic datasets enable the investigation of molecular mechanisms underlying NNV infection, thus may help further development of molecular breeding in marine fishery.

Nervous necrosis virus (NNV) is a kind of the betanodaviruses, which can cause viral nervous necrosis (VNN) and massive mortality in larval and juvenile stages of orange-spotted grouper (Epinephelus coioides). Due to the lack of viral genomes, virus-like particles (VLPs) are considered as one of the most promising candidates in vaccine study to control this disease. In this study, a type of VLPs, which was engineered on the basis of orange-spotted grouper nervous necrosis virus (OGNNV), was produced from prokaryotes. They possessed the similar structure and size to the native NNV. In addition, synthetic oligodeoxynucleotide (ODN) containing CpG motif was added in vaccines, and the expression patterns of several genes were analyzed after injecting with VLP and VLP with adjuvant (VA) to assess the regulation effect of vaccine for inducing immune responses. RT-PCR assays showed that six related genes in healthy tissues were ubiquitously expressed in all nine tested tissues. The vaccine alone was able to enhance the expression of genes, including MHCIa, MyD88, TLR3, TLR9 and TLR22 after vaccination, indicating that the vaccine was able to induce immune response in grouper. In liver, spleen and kidney, the gene expressions of VA group were all significantly higher than that of VLP group at 72 h post-stimulation, showing that the fish of VA challenge group obtained the longer-lasting protective immunity and resistance to pathogen challenge than that of VLP group. The data indicated that the efficacy of vaccine could be further enhanced by CpG ODN after vaccination and provided the reference for the development of future viral vaccine in grouper.