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Grass carp is an important aquaculture fish species in China that is affected by severe diseases, especially haemorrhagic disease caused by grass carp reovirus (GCRV). However, the mechanisms of GCRV invasion and infection remain to be elucidated. In the present study, Ctenopharyngodon idellus kidney (CIK) cells were infected with GCRV, harvested at 0, 8, 24, and 72 h post infection, respectively, and then subjected to transcriptomics sequencing. Each sample yielded more than 6 Gb of clean data and 40 million clean reads. To better understand GCRV infection, the process was divided into three phases: the early (0–8 h post infection), middle (8–24 h post infection), and late (24–72 h) stages of infection. A total of 76 (35 up-regulated, 41 down-regulated), 553 (463 up-regulated, 90 down-regulated), and 284 (150 up-regulated, 134 down-regulated) differently expressed genes (DEGs) were identified during the early, middle, and late stages of infection, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that DEGs were mainly involved in carbohydrate biosynthesis, transport, and endocytosis in the early stage, phagocytosis and lysosome pathways were mainly enriched in the middle stage, and programmed cell death, apoptosis, and inflammation were largely associated with the late stage. These results suggest GCRV infection is a gradual process involving adsorption on the cell surface, followed by endocytosis into cells, transport by lysosomes, and eventually resulted in cell necrosis and/or apoptosis. Our findings provide insight into the mechanisms of grass carp reovirus infection. [ABSTRACT FROM AUTHOR]

Basic leucine zipper transcription factor ATF-like (BATF)-3, belonging to activator protein 1 (AP-1) superfamily transcription factors, is essential for homeostatic development of CD8α+ classical dendritic cells activating CD8 T-cell responses to intracellular pathogens. In this study, the characteristics and cDNA cloning of the CiBATF3 molecule were described in grass carp (Ctenopharyngodon idella). CiBATF3 had abundant expression in immune-related organizations, including liver, spleen and gill, and grass carp reovirus (GCRV) infection had significantly changed its expression level. After Ctenopharyngodon idella kidney (CIK) cells were challenged with pathogen-associated molecular patterns (PAMPs), polyinosinic:polycytidylic acid (poly(I:C)) stimulation induced higher mRNA levels of CiBATF3 than that of lipopolysaccharide (LPS). Subcellular localization showed that CiBATF3-GFP was entirely distributed throughout cells and nuclear translocation of CiBATF3 was found after poly(I:C) treatment. Additionally, the interaction between CiBATF3 and interleukin 10 (IL-10) was proven by bimolecular fluorescence complementation (BiFC) system. The small interfering RNA (siRNA)-mediated CiBATF3 silencing showed that the mRNA of CiBATF3 and its downstream genes were down-regulated in vitro and in vivo. CiBATF3 played a negative regulatory role in the transcriptional activities of AP-1 and NF-κB reporter gene. In summary, the results may provide valuable information on fundamental functional mechanisms of CiBATF3. [ABSTRACT FROM AUTHOR]

Integrin β-1 (ITGB1) is a transmembrane protein belonging to the integrin family and it plays an important role in viral entry. In this study, the itgb1b gene of the rare minnow, Gobiocypris rarus, was cloned and analyzed. To investigate the possible role of itgb1b on grass carp reovirus (GCRV) infection, we generated an ITGB1b-deficient rare minnow (ITGB1b−/−) using the CRISPR/Cas9 system. Following stimulation with GCRV, the survival time of the -ITGB1b−/− rare minnows was extended in comparison to the wild-type minnows. Moreover, the relative copy number of GCRV and the level of clathrin-mediated endocytosis-associated and apoptosis-related gene expression in the ITGB1b−/− rare minnows was significantly lower than that of the wild-type minnows. These results suggested that the absence of itgb1b reduced viral entry efficiency and the expression of apoptosis-related genes. Moreover, the data suggested that itgb1b played an important role in mediating the entry of viruses into the cells via clathrin. Therefore, these findings provide novel insight into the function of itgb1b in the process of GCRV infection. [ABSTRACT FROM AUTHOR]