In vivo effects of adding singular or combined anti-oxidative vitamins and/or minerals to diets on the immune system of tilapia (Oreochromis hybrids) peripheral blood monocyte-derived, anterior kidney-derived, and spleen-derived macrophages

The interaction between lipid and vitamin D3 impacts lipid metabolism and innate immunity in Chinese mitten crabs Eriocheir sinensis

As a fat-soluble vitamin, vitamin D3 relies on fat to perform its biological function, affecting lipid metabolism and innate immunity. This study used different percentages of lipid and vitamin D3 diets to evaluate the synergistic effects on the growth, lipid metabolism and immunity of juvenile Eriocheir sinensis (5.83 ± 0.01 g) for 56 days, including low lipid (LL, 1.5%) and normal lipid (NL, 7.5%) and three levels of vitamin D3: low (LVD, 0 IU/kg), medium (MVD, 9000 IU/kg) and high (HVD, 27,000, IU/kg). The synergistic effect of lipid and vitamin D3 was not significant on growth but significant on ash content, total protein, hepatopancreas lipid content, hemolymph 1α,25-hydroxy vitamin D3 [1α,25(OH)2D3] content, hepatopancreas lipolysis and synthesis genes. Crabs fed normal lipid (7.5%) and medium vitamin D3 (9000 IU/kg) had the highest hepatopancreas index, hemolymph 1α,25(OH)2D3 content, antibacterial ability, immune-related genes and hepatopancreatic lipid synthesis genes expression, but down-regulated the lipolysis genes expression. In contrast, crabs fed diets with low lipid percentage (1.5%) had low growth performance, hemolymph 1α,25(OH)2D3, mRNA levels of lipid synthesis genes, antibacterial ability and immune-related gene expression. At the 1.5% lipid level, excessive or insufficient vitamin D3 supplementation led to the obstruction of ash and protein deposition, reduced growth and molting, aggravated the reduction in antioxidant capacity, hindered antimicrobial peptide gene expression and reduced innate immunity, and resulted in abnormal lipid accumulation and the risk of oxidative stress. This study suggests that diets' lipid and vitamin D3 percentage can enhance antioxidant capacity, lipid metabolism and innate immunity in E. sinensis. A low lipid diet can cause growth retardation, reduce antioxidant capacity and innate immunity, and enhance lipid metabolism disorder.

Protective Efficacy of Novel Oral Biofilm Vaccines against Photobacterium damselae subsp. damselae Infection in Giant Grouper, Epinephelus lanceolatus

Photobacterium damselae subsp. damselae is a pathogen that mainly infects a variety of fish species. There are many antibiotic-resistant strains of Photobacterium damselae subsp. damselae. In a previously published article, we described the production method for a novel oral biofilm vaccine. In the study reported herein, we confirmed the protective effect of the oral biofilm vaccine against Photobacterium damselae subsp. damselae. Twenty-eight days after vaccination, phagocytosis increased by 256% relative to the control group. The mean albumin–globulin ratios of the vaccine groups were significantly lower than the mean albumin–globulin ratios of the control group. There were no significant intergroup differences in lysozyme activity. Mean IgM titers were significantly higher in the vaccine group than in the control group. There was a significant upregulation of the TLR 3, IL-1β, and IL-8 genes in the spleen 28 days after vaccination. The cumulative mortality of the control fish was 84% after challenging fish with the Photobacterium damselae subsp. damselae, while the cumulative mortality of the oral biofilm vaccine (PBV) group was 32%, which was significantly higher than those of the whole-cell vaccine (PWV) and chitosan particle (CP) groups. There is minimal published research on the prevention and treatment of Photobacterium damselae subsp. damselae infection; therefore, this oral biofilm vaccine may represent a new method to fill this gap.