Yellow mealworm (Tenebrio Molitor) enhances intestinal immunity in largemouth bass (Micropterus salmoides) via the NFκB/survivin signaling pathway

This study aimed to elucidate the mechanisms of yellow mealworm (Tenebrio Molitor, YM) in intestinal immunity and health. Largemouth bass, as an enteritis modeling animal, were fed 3 diets containing YM at 0% (YM0), 24% (YM24) and 48% (YM48). The YM24 group had reduced levels of proinflammatory cytokines, while the YM48 group experienced a negative impact on intestinal health. Next, the Edwardsiella tarda (E. tarda) challenge test consisted of 4 YM diets, 0% (EYM0), 12% (EYM12), 24% (EYM24), and 36% (EYM36). The EYM0 and EYM12 groups exhibited intestinal damage and immunosuppression by the pathogenic bacteria. However, the above adverse phenotypes were attenuated in the EYM24 and EYM36 groups. Mechanistically, the EYM24 and EYM36 groups enhanced intestinal immunity in largemouth bass via activating NFκBp65 and further upregulating survivin expression to inhibit apoptosis. The results identify a protective mechanism of YM as a novel food or feed source by improving intestinal health.

Chimonanthus nitens Oliv Polysaccharides Modulate Immunity and Gut Microbiota in Immunocompromised Mice

To investigate the immunomodulatory activities of Chimonanthus nitens Oliv polysaccharides (COP1), an immunosuppressive mouse model was generated by cyclophosphamide (CY) administration and then treated with COP1. The results demonstrated that COP1 ameliorated the body weight and immune organ (spleen and thymus) index of mice and improved the pathological changes of the spleen and ileum induced by CY. COP1 strongly stimulated the production of inflammatory cytokines (IL-10, IL-12, IL-17, IL-1β, and TNF-α) of the spleen and ileum by promoting the mRNA expressions. Furthermore, COP1 had immunomodulatory activity by increasing several transcription factors (JNK, ERK, and P38) in the mitogen-activated protein kinase (MAPK) signaling pathway. Related to the above immune stimulatory effects, COP1 positively affected the production of short-chain fatty acids (SCFAs) and the expression of ileum tight junction (TJ) protein (ZO-1, Occludin-1, and Claudin-1), upregulated the level of secretory immunoglobulin A (SIgA) in the ileum and microbiota diversity and composition, and improved intestinal barrier function. This study suggests that COP1 may provide an alternative strategy for alleviating chemotherapy-induced immunosuppression.

Viral Nonstructural Protein 1 Induces Mitochondrion-Mediated Apoptosis in Mink Enteritis Virus Infection

Mink enteritis virus (MEV), an autonomous parvovirus, causes acute hemorrhagic enteritis in minks. The molecular pathogenesis of MEV infection has not been fully understood. In this study, we observed significantly increased apoptosis in the esophagus, small intestine, mesenteric lymph nodes, and kidney in minks experimentally infected with strain MEVB. In vitro infection of feline F81 cells with MEVB decreased cell viability and induced cell cycle arrest at G₁ phase and apoptosis. By screening MEV nonstructural proteins (NS1 and NS2) and structural proteins (VP1 and VP2), we demonstrated that the MEV NS1 induced apoptosis in both F81 and human embryonic kidney 293T (HEK293T) cells, similar to that induced during MEV infection in minks. We found that the NS1 protein-induced apoptosis in HEK293T cells was mediated not by the death receptor but by the mitochondrial pathway, as demonstrated by mitochondrial depolarization, opening of mitochondrial transition pore, release of cytochrome c, and activation of caspase-9 and -3. Moreover, in NS1-transfected cells, we observed an increase of Bax expression and its translocation to the mitochondria, as well as an increased ratio of the Bax/Bcl-2, reactive oxygen species (ROS) production, and activated p38 mitogen-activated protein kinase (MAPK) and p53. Taken together, our results demonstrated that MEV induces apoptosis through activation of p38 MAPK and the p53-mediated mitochondrial apoptotic pathway induced by NS1 protein, which sheds light on the molecular pathogenesis of MEV infection.IMPORTANCE MEV causes fatal hemorrhagic enteritis in minks. Apoptosis is a cellular mechanism that effectively sacrifices virus-infected cells to maintain homeostasis between the virus and host. In this study, we demonstrated that MEV induces apoptosis both in vivo and in vitro Mechanistically, the viral large nonstructural protein NS1 activates p38 MAPK, which leads p53 phosphorylation to mediate the mitochondrial apoptotic pathway but not the death receptor-mediated apoptotic pathway. This is the first report to uncover the mechanism underlying MEV-induced apoptosis.

Molecular cloning, tissue distribution, and immune function of goose TLR7

TLR7 is a transmembrane endosomal protein that plays an essential role in innate antiviral responses via the recognition of conserved viral molecular patterns. Here, we cloned the full-length cDNA of goose TLR7 and carried out a molecular characterization of goose TLR7. The goose TLR7 gene is 3900 bp and encodes a 1045 amino acid protein with high homology to poultry (93% to duck and 83% to chicken). Similar conclusions were made by phylogenetic analysis. The predicted protein secondary structure of goose TLR7 contained a conserved Toll/interleukin-1 receptor domain and characteristic leucine-rich repeat regions, which has also been reported for duck TLR7. Additionally, the tissue distribution of goose TLR7 suggests that immune-associated tissues, especially the cecal tonsil and bursa of Fabricius, have high goose TLR7 expression levels. Goose TLR7 is abundantly expressed in lung tissues, which is distinct from its expression in chickens. Similar to duck TLR7, goose spleen mononuclear cells (MNCs) exposed to the mammalian TLR7 agonists R848 and Imiquimod showed significant induction of the production of proinflammatory cytokines and IFN-α. New type gosling viral enteritis virus (NGVEV) infection resulted in high mRNA expression levels of goose TLR7 in the spleen. By contrast, no direct interaction between NGVEV and goose TLR7 was detected after infecting goose spleen MNCs with NGVEV in vitro. However, triggering of goose TLR7 resulted in the rapid up-regulation of proinflammatory cytokines and anti-viral molecules, suggesting that goose TLR7 plays an important role in anti-viral defense.

Efficacy study and field application of an inactivated new type gosling viral enteritis virus vaccine for domestic geese

New type gosling viral enteritis virus (NGVEV) caused a serious disease in naive juvenile goslings. In the described studies the performance of 2 vaccines was analyzed: a vaccine containing adjuvanted inactivated NGVEV and a vaccine containing adjuvanted inactivated NGVEV and recombinant goose IL-2. Breeder geese were subcutaneously vaccinated at the beginning of the egg production period with the vaccines. Breeder geese sham vaccinated with PBS served as control. The cellular and humoral immune responses of the vaccinated breeder geese, as well as the presence of maternally derived antibody to NGVEV, were investigated by ELISA, virus neutralization test, and lymphocyte proliferation assay, respectively. A significantly higher immunogenicity (P < 0.05) was induced by the inactivated NGVEV-recombinant goose IL-2 adjuvant vaccine compared with the inactivated NGVEV vaccine. The offspring of the vaccinated birds were challenged with virulent NGVEV (100 50% lethal dose) and the protective efficacy of the vaccines was determined. Furthermore, in a field trial the efficacy of the inactivated NGVEV vaccine was recorded from years 2003 to 2007. No clinical signs or abnormal health status were observed in the vaccinated breeder geese and the progeny. After a single application, >80% protection was shown in the progeny of geese vaccinated against NGVEV challenge for approximately 5 mo. The extensive field trials further demonstrated that vaccination of breeder geese with the inactivated NGVEV vaccine could be a safe and efficacious means to control NGVE disease. Moreover, the level of maternally derived NGVEV antibody titer in the egg yolk reflected the level of NGVEV antibodies in the breeder geese, suggesting that the egg yolk could be used to monitor the vaccination efficacy in commercial goose breeder flocks.