A tributyrin-monolaurin complex protects piglets against PEDV infection via viral inhibition, lipid metabolism restoration, and microbiota modulation

Abstract

Porcine epidemic diarrhea virus (PEDV) is a major pathogen causing severe diarrhea and intestinal damage in piglets. Monolaurin (GML) and tributyrin (TB) are well-documented functional lipids with intestinal health benefits, but their combined efficacy against PEDV infection remains unclear. The present study first investigated the anti-PEDV effect of GML, TB, and their mixtures using PEDV-infected Vero cells. Then, the effects of a microencapsulated TB-GML complex (PE) were evaluated in PEDV-infected piglets, focusing on its protective mechanisms. Vero cells were simultaneously treated with PEDV and graded concentrations of GML (20-40 μmol/L), TB (0.25-0.50 mmol/L), or their combinations to determine for synergistic antiviral effects. In vivo, a total of 30 piglets (2.49 ± 0.38 kg), 7-d-old, were randomly assigned to three groups: negative control (NC), PEDV, and PE + PEDV. After a 3-d adaptation period, piglets in the PE + PEDV group received an oral dose of PE at 100 mg/kg body weight for 7 consecutive days. On d 8, piglets in the PEDV and PE + PEDV groups were orally inoculated with 1 × 10 6 50% tissue culture infective dose (TCID 50 ) of PEDV per piglet. The experiment lasted for 11 d. The results showed that 40 μmol/L GML alone, or 0.25 mmol/L TB combined with 20-40 μmol/L GML, suppressed virus replication ( P = 0.023). The PE administration improved villus morphology and increased expression of genes involved in water and ion transport in the jejunum, including AQP10 , KCNJ13 , NHE2 , and NHE3 ( P < 0.05). Additionally, PE reduced serum interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α) levels, and downregulated jejunal relative mRNA expression of inflammation-related genes, mainly IL-8 , IL-1β , and CXCL2 ( P < 0.05). The PE reversed the enhanced antioxidant stress response in the jejunum by reducing total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and myeloperoxidase (MPO) activities ( P < 0.05). The PE inhibited PEDV replication, downregulated relative mRNA expression of IFN-β and its downstream genes, and reduced protein abundance of PEDV-N ( P < 0.05). Transcriptomic and quantitative real-time PCR (RT-qPCR) analyses revealed that PE restored lipid metabolic homeostasis by balancing lipogenesis, lipid transport, and fatty acid β-oxidation. Moreover, PE increased the abundance of Proteobacteria, Bacteroidota, Bacteroides , and Halomonas , while decreasing the abundance of Firmicutes and Lactobacillus . In conclusion, PE mitigated inflammation, enhanced antioxidant and antiviral capacities, while alleviating disruptions in water and ion transport, lipid metabolism, and gut microbiota.