Gene expression profile after Spring Viraemia Carpae Virus (SVCV) infection in zebrafish mutants rag1 -/- versus wt
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ABSTRACT: Immune responses in higher vertebrates are classically separated into innate and adaptive (or specific) immunity. However, important gaps of knowledge about how adaptive responses are generated in lower vertebrates still remain unsolved. In order to explore the relative importance of adaptive and innate immune responses, we have studied zebrafish transcriptional responses to an infection with the Spring Viraemia of Carp virus (SVCV) in rag1-/- zebrafish mutants compared to wild type zebrafish by using both genome wide and immunological-targeted gene expression microarrays.
Project description:Immune responses in higher vertebrates are classically separated into innate and adaptive (or specific) immunity. However, important gaps of knowledge about how adaptive responses are generated in lower vertebrates still remain unsolved. In order to explore the relative importance of adaptive and innate immune responses, we have studied zebrafish transcriptional responses to an infection with the Spring Viraemia of Carp virus (SVCV) in rag1-/- zebrafish mutants compared to wild type zebrafish by using both genome wide and immunological-targeted gene expression microarrays. Both wild type (wt) and mutant (rag1) zebrafish were divided in two groups with 3 individuals per group. First group was infected with 10^5 pfu per ml of SVCV, second group was mock-infected. Two days after challenge zebrafish were sampled, head kidney and spleen of each fish were extracted and pooled between each group. The experiment was repeated once to obtain two biological replicates.
Project description:The hypoxia signaling pathway controls hypoxia adaptation and tolerance of organisms, which is regulated by multiple mechanisms. Viral infection elicits various pathophysiological responses in the host. However, whether viral infection can affect the hypoxia response is still largely unknown. In this study, we found that Spring viraemia of carp virus (SVCV) infection in zebrafish caused symptoms similar to those in zebrafish under hypoxic conditions. Further assays indicated that SVCV infection activated the hypoxia signaling pathway in zebrafish. In addition, SVCV infection caused increased glycolysis and ROS levels in cells. Mechanistically, SVCV-G protein interacted with hif1α-a/b and attenuated their K48-linked polyubiquitination, leading to their stabilization and subsequent enhancement of target gene expression. Moreover, treatment with the HIF1α-specific inhibitor PX478 enhanced the antiviral ability against SVCV infection in zebrafish and zebrafish cells. This study reveals a relationship between SVCV infection and the hypoxia signaling pathway in fish, and provides a strategy for reducing the damage of viral disease in the aquaculture industry.
Project description:During viral infection, a large number of immune response signaling molecules including the interferon regulatory (IRF) family and type I interferon (IFN) transcribe. The exact identity and expression levels of fish IRFs and type-I IFNs during viral infection remains largely unknown. Here, we utilized Illumina sequencing technology to determine differential expression patterns for both zebrafish IRFs and type-I IFNs during two stages of SVCV infection, i.e. 6h and 24h post-infection. For 12 zebrafish IRFs, we identified DrIRF1 mRNA as one of the most abundant in normal tissues and also in SVCV-infected tissues, but DrIRF11 had a very weak basal expression and was almost not induced by SVCV infection. We also identified the highly basal expression of DrIRF7, which together with DrIRF3, was highly induced by SVCV infection. For type-I IFNs, zebrafish has four IFN genes, three of which, IFN1/2/3, particularly IFN 1 and IFN 3, were significantly transcribed under the same conditions.
Project description:In the present study, we report the functional characterization of zebrafish trim2b. we show that zebrafish trim2b plays a protective role in the host defense against SVCV infection. During SVCV infection, the in vivo studies revealed that trim2b overexpression led to the decreased virus loads and increased survival rate. Zebrafish trim2b deficiency led to the increased virus loads and decreased survival rate. In addition, Zebrafish trim2b deficiency leads higher numbers of immune related DEGs and signaling pathways enriched during the SVCV infection or uninfection. Among them, NOD-like receptor signaling pathway was significantly enriched. The present study characterized two NLRs degraded by trim2b plays a negative role in the host defense against SVCV infection.
Project description:We describe here transcripts induced after infection of zebrafish with Spring Viremia Carp Virus (SVCV). Two days after infection, differentially expressed transcript levels from selected immune-related zebrafish genes were studied in internal organs (pooled spleen, head kidney). Also, transcripts from resistant fishes to viral infection one month after inoculation were studied.
Project description:Because fin base is supposed to be the entry zone of some fish virus, we wanted to know which transcripts are induced after infection of zebrafish with Spring Viremia Carp Virus (SVCV). Two days after infection, differentially expressed transcript levels from selected immune-related zebrafish genes were studied in zebrafish fins. Also transcripts from resistant fishes to viral infection one month after inoculation were studied.
Project description:We describe here transcripts induced after infection of zebrafish with Spring Viremia Carp Virus (SVCV). Two days after infection, differentially expressed transcript levels from selected immune-related zebrafish genes were studied in internal organs (pooled spleen, head kidney). Also, transcripts from resistant fishes to viral infection one month after inoculation were studied. Three different experiments were performed to get three biological replicates. Fishes were divided into two groups in each experiment. First group was infected by immersion with SVCV 10^7 pfu/ml, second group was used as a control of non-infected fishes. 6 fishes per group were sacrificed two days post infection, whereas the rest of the infected fishes from the three experiments were maintained for 30 days in the aquariums and then survivors (six for experiment) were sacrificed. This submission includes three biological replicate groups for the non-infected fish and the two days post-infected fish, and two biological replicate groups for the 30 days post-infected fish.
Project description:Vertebrates are protected from pathogens by an adaptive and an innate immune system. In mammals, loss of the adaptive immune system severely compromises viability. Zebrafish, in contrast, can survive for relatively long without adaptive immunity, as demonstrated by the immuno-deficient Rag1 mutant. Here, we examine whether the innate immune system is activated in the mutant, and ask whether this has any effect on the nervous system, given the finding that inflammation is linked to neurodegeneration in higher vertebrates. Using microarray analysis of the olfactory epithelium, we show that innate immune responses are upregulated. Neuronal genes are down-regulated, and immunofluorescence for the neural marker HuC shows a progressive loss of olfactory sensory neurons in mutants. Propodium iodide uptake indicates a corresponding increase in cell death. Rag1 mutant fish progressively lose their sensitivity to an olfactory cue, the alarm pheromone Schreckstoff, indicating that neuro-degeneration has a behavioral significance. Taken together, these data establish that immuno-deficiency in the zebrafish is accompanied by neuro-inflammation and loss of neurons. The microarray data document transcriptional changes associated with activation of innate immunity in the context of immunodeficiency and also identify novel genes that are potentially related to function of the olfactory system. Keywords: analysis of mutant A total of 6 RNA samples were used for hybridization. 3 were from the olfactory rosettes of wild type adult zebrafish and 3 were from Rag1 mutants.
Project description:In the last years, the innate immune response has gained importance since evidences indicate that, after an adequate priming protocol, it is possible to obtain some prolonged and enhanced immune response. Nevertheless, several factors, such as timing and method of administration of the immunostimulants need to be carefully considered. An inappropriate protocol can transform the treatments into a double-edged sword for the teleost immune system, resulting in a stressful and immunosuppressive status. In this work, we analyzed the long-term effect of different stimuli (β-glucans, lipopolysaccharide and Polyinosinic:polycytidylic acid) on the transcriptome modulation induced by Spring Viraemia Carp Virus (SVCV) in adult zebrafish (Danio rerio) and on the mortalities caused by this infection. At 35 days post-immunostimulation the transcriptome was found to be highly altered compared to the control fish, and these stimuli also conditioned the response to SVCV challenge, especially in the case of β-glucans. No protection against SVCV was found with any of the stimuli and even non-significant higher mortalities were observed, especially with β-glucans. However, at short-term (a pre-stimulation with β-glucan and infection after 7 days) a slight protection was observed after infection. The transcriptome response in zebrafish kidney at 35 days post-treatment with β-glucans revealed a significant response associated to stress and immunosuppression. The identification of genes differentially expressed before and after the infection seem to indicate a high energy cost of the immunostimulation prolonged in time that could explain the lack of protection against the SVCV. The differential response to stress, alterations in the lipid metabolism, the tryptophan-kynurenine pathway and the interferon-gamma signaling seem to be some of the mechanisms involved in this particular response, which means the end of the trained immunity and the beginning of a stressful status characterized by immunosuppression.