Bovine viral diarrhea virus (BVDV) is a pathogen associated with substantial economic losses in the dairy cattle industry. Currently, there are no effective vaccines against BVDV. Melatonin (MT) has been shown to have anti-inflammatory and anti-viral properties, and the use of MF59 in vaccines significantly enhances vaccine efficiency. Here, MT and MF59 were added into the E^rns-LTB vaccine. Subsequently, their inhibitory activity on the NF-κB signaling pathway in Mardin-Darby Bovine Kidney cells and the hippocampus was assessed using western blot and quantitative reverse transcription PCR. The findings revealed that MT in the E^rns-LTB vaccine decreases the phosphorylation of p65 proteins caused by BVDV infection. In addition, MT decreased the mRNA levels of IL-1β and IL-6 in vitro, but increased the production of IFN-α, IFN-β, Mx1 in vitro, brain-derived neurotrophic factor, cyclic amp response element-binding protein, and the stem cell factor in vivo. Furthermore, treatment with E^rns-LTB + MF59 + MT stimulated the production of T lymphocytes, alleviated pathological damage, decreased expressions of BVDV antigen, and tight junction proteins in mice. These findings imply that MT has potential for use in the E^rns-LTB vaccine to inhibit BVDV infection and regulate the immune responses of T-cells by inhibiting the NF-κB signaling pathway.

Bovine viral diarrhea virus (BVDV) is a highly contagious viral disease which causes economic losses to the cattle industry. Ethyl gallate (EG) is a phenolic acid derivative which has various potentials to modulate the host response to pathogens, such as via antioxidant activity, antibacterial activity, inhibition of the production of cell adhesion factors, and so on. This study aimed to evaluate if EG influences BVDV infection in Madin-Darby Bovine Kidney (MDBK) cells, and to understand the antiviral mechanism. Data indicated that EG effectively inhibited BVDV infection by co-treatment and post-treatment in MDBK cells with noncytotoxic doses. In addition, EG suppressed BVDV infection at an early stage of the viral life cycle by blocking entry and replication steps but not viral attachment and release. Moreover, EG strongly inhibited BVDV infection by promoting interferon-induced transmembrane protein 3 (IFITM3) expression, which localized to the cytoplasm. The protein level of cathepsin B was significantly reduced by BVDV infection, whereas with treatment with EG, it was significantly enhanced. The fluorescence intensities of acridine orange (AO) staining were significantly decreased in BVDV-infected cells but increased in EG-treated cells. Finally, Western blot and immunofluorescence analyses demonstrated that EG treatment significantly enhanced the protein levels of autophagy markers LC3 and p62. Chloroquine (CQ) significantly increased IFITM3 expression, and Rapamycin significantly decreased it. Thus, EG may regulate IFITM3 expression through autophagy. Our results showed that EG could have a solid antiviral activity on BVDV replication in MDBK cells via increased IFITM3 expression, lysosomal acidification, protease activity, and regulated autophagy. EG might have value for further development as an antiviral agent.

This study aimed to investigate the effects of arginine (Arg) or N-carbamylglutamate (NCG) on jejunum development, the global arginine bioavailability ratio (GABR), and stress-related indices in young rex rabbits. Forty-five litters of newborn rabbits with similar litter weights and sizes were randomly divided into five groups and fed a basal diet (con group), basal diet + 0.3% Arg (0.3% Arg group), basal diet + 0.6% Arg (0.6% Arg group), basal diet + 0.03% NCG (0.03% NCG group), or basal diet + 0.06% NCG (0.06% NCG group). After weaning at 35 days, eight healthy young rabbits with similar body weights were selected from each group and slaughtered on the 36th day. Serum and jejunum samples were collected for index analysis. Arg or NCG significantly affected the jejunum structure development in the young rabbits. The villus height (V) in the treatment groups was significantly higher than that in the con group (p < 0.05) and was highly significantly improved in the 0.6% Arg group (p < 0.01). The crypt depth (C) in 0.6% Arg and 0.06% NCG groups was significantly lower than that in the con, 0.3% Arg, and 0.03% NCG groups (p < 0.05). Compared with the con group, the V/C ratio was significantly increased in the treatment groups (p < 0.05) and was excessively and significantly increased in the 0.6% Arg and 0.06% NCG groups (p < 0.01). Compared with the con group, the Nitric-Oxide (NO) levels and inducible Nitric-Oxide Synthase (iNOS) activity in serum were significantly increased in the treatment groups. The NO levels in the jejunum were also increased in the treatment groups; however, there were no significant differences (p > 0.05). The iNOS activity and mRNA expression in the jejunum of the 0.6% Arg and 0.06% NCG groups were significantly higher than those in the con group (p < 0.05). Compared with the con group, the concentration of serum corticosterone in the 0.3% Arg, 0.6% Arg, and 0.06% NCG groups was significantly reduced. Adding Arg or NCG to the basal diet significantly increased the concentration and gene mRNA expression levels of heat shock protein 70 (HSP70) in the jejunum (p < 0.05). The expression level in the 0.6% Arg and 0.06% NCG groups was significantly higher than that in the con group (p < 0.01). At 36 days, Arg and NCG improved the GABR. In the 0.6% Arg group, the GABR was increased by 16.92%. The GABR was <0.8 at the time of weaning. The Arg levels in the body did not meet the needs of the young animals. In the trial, Arg or NCG supplementation in the diet significantly increased iNOS activity and gene mRNA expression, promoting NO synthesis. Thus, it can improve jejunal morphological and structural development. Adding Arg or NCG increased HSP70 mRNA expression levels, enhanced intestinal stress tolerance, and improved intestinal health. During the lactation period, adding Arg or NCG increased the GABR, but the GABR was <0.8 during weaning.