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A strain of Clostridium butyricum (Cb) was isolated and characterized as an immunostimulant for gibel carp. Healthy gibel carp were fed and immersed with or without Cb (group Cb + V and group V), and then were intraperitoneally injected with Carassius auratus herpesvirus (CaHV) respectively. The fish began to die at 4 days post injection (dpi). The overall survival rate of group Cb + V (45%) is more than that of group V (11%), which indicated the significant protection effect of Cb. The RT-qPCR results showed that virus major capsid protein gene (MCP) copy numbers of group Cb + V was significantly lower (P < 0.05) than that of group V at 3 dpi. Meanwhile, the expression levels of the four host innate immunity-related genes (IL11, IRF7, PKR, and Mx) were significantly higher (P < 0.01) in group Cb + V than in group V at this time point. IRF7 and PKR also had significantly higher expression levels in group Cb + V than in group V at 0 dpi, which revealed enhanced immune responses in Cb-treated fish. Treatment with Cb prompted stronger host immune responses at the early stage of virus infection, and then resulted in the survival of gibel carp. To our knowledge, it is the first report about the immune protection of fish from herpesvirus by probiotics. [ABSTRACT FROM AUTHOR]

Abstract Viruses are important and lethal pathogens that hamper aquatic animals. The result of the battle between host and virus would determine the occurrence of diseases. The host will fight against virus infection with various responses such as innate immunity, adaptive immunity, apoptosis, and so on. On the other hand, the virus also develops numerous strategies such as immune evasion to antagonize host antiviral responses. Here, We review the research advances on virus mediated immune evasions to host responses containing interferon response, NF-κB signaling, apoptosis, and adaptive response, which are executed by viral genes, proteins, and miRNAs from different aquatic animal viruses including Alloherpesviridae , Iridoviridae , Nimaviridae , Birnaviridae , Reoviridae , and Rhabdoviridae. Thus, it will facilitate the understanding of aquatic animal virus mediated immune evasion and potentially benefit the development of novel antiviral applications. Highlights • Itemized are host antiviral responses in aquatic animals including fish and shrimp. • Summed up are aquatic animal virus and viral components mediated evasions. • Outlined are three main immune evasion strategies of aquatic animal virus. [ABSTRACT FROM AUTHOR]

Infection with Rana grylio virus (RGV), an iridovirus isolated in China in 1995, resulted in a high mortality rate in frogs. The complete genome sequence of RGV was determined and analyzed. The genomic DNA was 105,791 bp long, with 106 open reading frames (ORFs). Dot plot analysis showed that the gene order of RGV shared colinearity with three completely sequenced ranaviruses. A phylogenetic tree was constructed based on concatenated sequences of iridovirus 26 core-gene-encoded proteins, and the result showed high bootstrap support for RGV being a member of the genus Ranavirus and that iridoviruses of other genera also clustered closely. A microRNA (miRNA) prediction revealed that RGV could encode 18 mature miRNAs, many of which were located near genes associated with virus replication. Thirty-three repeated sequences were found in the RGV genome. These results provide insight into the genetic nature of RGV and are useful for laboratory diagnosis for vertebrate iridoviruses. [ABSTRACT FROM AUTHOR]

Abstract: Heat shock proteins (Hsps) are a family of highly conserved cellular proteins present in all organisms, mediating a range of essential housekeeping and cytoprotective functions as well-known molecular chaperons and recently as regulators of the immune response. By subtractive suppression hybridization, three Hsp40 homologues have been identified in the flounder (Paralichthys olivaceus) embryonic cells (FEC) after treatment with UV-inactivated turbot (Scophthalmus maximus L.) rhabdovirus (SMRV), termed PoHsp40A4, PoHsp40B6 and PoHsp40B11, whose encoded proteins all possess the conserved DnaJ domain, a signature motif of the Hsp40 family. Based on different protein structure and phylogenetic analysis, they can be categorized into two subfamilies, PoHsp40A4 for Type I Hsp40, PoHsp40B6 and PoHsp40B11 for Type II Hsp40. Further expression analysis revealed two very different types of kinetics in response either to heat shock or to virus infection, with a marked induction for PoHsp40A4 and a weak one for both PoHsp40B6 and PoHsp40B11. A very distinct tissue distribution of mRNA was also revealed among the three genes, even between PoHsp40B6 and PoHsp40B11. This is the first report on the transcriptional induction of Hsp40 in virally stimulated fish cells, and the differential expressions might reflect their different roles in unstressed and stressed cells. [Copyright &y& Elsevier]

• Gibel carp IFNa and IFNc display significantly antiviral potential to viral infection. • ISRE motifs within promoters are responsible for the induction of carp IFN and IFNc by diverse stimuli including themselves. • Gibel carp IFNa and IFNc have different-sized 3′UTR that is a potential factor for regulation of IFN response. Fish interferon (IFN)-mediated antiviral innate immunity is the first line of defense against virus invasion. In the present study, we identify two fish IFN genes (here tentatively named IFNa and IFNc) with different-sized 3′ UTRs from clone F strain of gibel carp Carassius auratus gibelio. Carp IFNa has a relatively short 3′UTR without AU-rich elements (AREs) but IFNc has a long one with 9 AREs. Functionally, carp IFNa and IFNc display significantly antiviral potential to viral infection, likely through induction of downstream IFN-stimulated genes (ISGs). Both carp IFN genes are induced by viral infection, poly(I:C) treatment and IRF3/7, which are ascribed to the IFN-sensitive response elements (ISRE) within their promoters. Carp IFN genes are also induced by each other and by themselves, indicating existence of a positive feedback loop in fish IFN-mediated antiviral immune response. Comparative analyses of 3′UTR-mediated expression regulation at mRNA and protein levels show that the ARE-containing 3′UTR of carp IFNc rather than the short 3′UTR of carp IFNa promotes mRNA decay but instead results in high-level protein expression, indicating that 3′UTR of fish IFN mRNAs might be a potential factor for regulation of IFN-mediated antiviral immune response. Considering a fact that a given protein function is largely related to its protein level, these results suggest that both promoter and 3′UTR contribute to the transcription and translation of fish IFN genes, thus shaping their eventually antiviral potential. [ABSTRACT FROM AUTHOR]

Highlights: [•] First characterization of MHC alleles in the Chinese giant salamander Andrias davidianus. [•] Anda-MHC genes exhibit high allelic diversity maintained by positive selection acting on the PBR. [•] Two isoforms (full-length and splice transcripts) of Anda-MHC coexist in various tissues. [•] Anda-MHC variants display similar subcellular localization with the full-length transcripts. [•] Anda-MHC gene expression was increased during viral infection. [Copyright &y& Elsevier]

Abstract: Voltage-dependent anion channel (VDAC, also known as mitochondrial porin) is acknowledged to play an important role in stress-induced mammalian apoptosis. In this study, Paralichthys olivaceus VDAC (PoVDAC) gene was identified as a virally induced gene from Scophthalmus Maximus Rhabdovirus (SMRV)-infected flounder embryonic cells (FEC). The full length of PoVDAC cDNA is 1380bp with an open reading frame of 852bp encoding a 283 amino acid protein. The deduced PoVDAC contains one α-helix, 13 transmembrane β-strands and one eukaryotic mitochondrial porin signature motif. Constitutive expression of PoVDAC was confirmed in all tested tissues by real-time PCR. Further expression analysis revealed PoVDAC mRNA was upregulated by viral infection. We prepared fish antiserum against recombinant VDAC proteins and detected the PoVDAC in heart lysates from flounder as a 32kDa band on western blot. Overexpression of PoVDAC in fish cells induced apoptosis. Immunofluoresence localization indicated that the significant distribution changes of PoVDAC have occurred in virus-induced apoptotic cells. This is the first report on the inductive expression of VDAC by viral infection, suggesting that PoVDAC might be mediated flounder antiviral immune response through induction of apoptosis. [Copyright &y& Elsevier]