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Interleukin 10 (IL-10), a pleiotropic cytokine, plays an essential role in multiple immunity responses. In the current study, the sequences of IL-10 family were identified from spotted knifejaw (Oplegnathus punctatus) whole genome, and O. punctatus IL-10 (OpIL-10) was cloned and characterized. OpIL-10 encodes 187 amino acids with a typical IL-10 family signature motif and predicted α-helices. It shared high identities with Notolabrus celidotus IL-10 and Epinephelus Lanceolatus IL-10. OpIL-10 was widely detected in healthy tissues, with the abundant expression in liver and skin. It was significantly up-regulated in the six immune-related tissues (liver, spleen, kidney, intestine, gill and skin) after infection against Vibrio harveyi and spotted knifejaw iridovirus (SKIV). Dual-luciferase analysis showed that OpIL-10 overexpression could suppress the activity of NF-κB. Meanwhile, OpIL-10 knockdown caused the down-regulation of five immune-related genes in JAK2/STAT3 signaling pathway and NF-κB signaling pathway, including IL-10R2 , TYK2 , STAT3 , NOD2 , and IκB. In addition, LPS and poly I:C stimulated expression of pro-inflammatory cytokines, including IL-6 , IL-1β , IL-8 , and IL-12 , were lower with recombinant OpIL-10 (rOp IL-10) than the control group, indicating the anti-inflammatory roles of rOpIL-10. Taken together, these results indicated OpIL-10 as a negative regulator in the inflammatory responses of spotted knifejaw against bacterial and viral infection, which would help us better understand the role of IL-10 in teleost immunity. • OpIL-10 was identified and characterized from spotted knifejaw (Oplegnathus punctatus). • OpIL-10 was expressed in multiple tissues and upregulated in six immune-related tissues after bacterial and viral infection. • OpIL-10 could regulate JAK2/STAT3 signaling pathway and NF-κB signaling pathway. • Recombinant OpIL-10 protein had an inhibitory effect on the expression of proinflammatory cytokines. • OpIL-10 plays a negatively regulator in the immune response against bacterial and viral infection in spotted knifejaw. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV) is a fatal pathogen threatening global crustacean industry with no commercially available drugs to control. Herbal medicines have been widely used to treat a number of viral infections, which could offer a rich reserve for antiviral drug discovery. Here, we evaluated the inhibition activities of 30 herbal medicines against WSSV in Chinese mitten crab Eriocheir sinensis. A WSSV infection model in E. sinensis was firstly established in order to determine the antiviral effects of the plant extracts and to explore the potential action mechanisms. Results showed that the highest anti-WSSV activity was obtained by the treatment of Ophiopogon japonicus extract (93.03%, 100 mg/kg). O. japonicus treatment decreased viral loads in a dose-dependent manner and significantly improved the survival of WSSV-challenged crabs. O. japonicus reduced the expression of vital genes in viral life cycle in vivo , particularly for the immediate-early stage gene ie1. Further results indicated that O. japonicus could repress the JAK-STAT signaling pathway to block ie1 transcription. Moreover, O. japonicus could modulate certain immune genes such as the myosin , toll-like receptor , crustin , and prophenoloxidase in the interactions between WSSV and crabs. The up-regulated expression of pro-autophagic factors (Gabarap and Atg7) and elevated levels of antioxidant enzymes (SOD, CAT and GSH) suggested that O. japonicus may induce autophagy and attenuate WSSV-induced oxidative stress. Taken together, O. japonicus could inhibit WSSV proliferation and improve the survival of WSSV-challenged crabs. Thus, O. japonicus may have the potential to be developed as a preventive or therapeutic agent against WSSV, and its effective compounds merit further isolation and identification. • The WSSV infection model was established and evaluated in Eriocheir sinensis for the first time. • Ophiopogon japonicus restrains WSSV proliferation and improves survival of WSSV-challenged crabs. • O.japonicus represses the JAK/STAT signaling pathway to block the transcription of WSSV early gene. • Ophiopogon japonicus induces immune response in crabs. • O.japonicus induces apoptosis-related factors and enhances anti-oxidative activity in WSSV-challenged crabs. [ABSTRACT FROM AUTHOR]