Probiotic Gordonia alkanivorans Enhances Phagocytic Function of Porcine Alveolar Macrophages and Modulates Immune Responses in Piglets

This study aimed to evaluate effect of <i>Gordonia alkanivorans</i> on phagocytic activity of porcine alveolar macrophages (PAMs) and immune function in piglets. Quantitative PCR and fluorescence tracing were used to measure phagocytic efficiency of <i>G. alkanivorans</i>-intervened PAMs against PRRSV and <i>E. coli</i>. Sixty-four 45-day-old cross-bred piglets with equal sex were randomly divided into four groups (<i>n</i> = 16/group). Growth performance, immune function, and intestinal flora were analyzed. <i>G. alkanivorans</i> extract exhibited half cytotoxic concentration of 36.43 mg/mL, half effective concentration of 0.1009 mg/mL, and half inhibitory concentration of 0.0043 mg/mL in PAMs, significantly increasing their phagocytic efficiency by 98.5% against PRRSV and 2.31- to 13.46-fold against <i>E. coli</i>. Dietary supplementation with <i>G. alkanivorans</i> elevated antibody-positive rates against classical swine fever virus (47.92%) and pseudorabies virus (14.58%), modified serum cytokine: Interleukin (IL)-1β, IL-2, Tumor Necrosis Factor -α, Interferon (IFN)-α, IFN-γ, IL-4, and IL-10 (-144.51% to +191.72%). It increased intestinal operational taxonomic units by 152%, the Shannon index by 14.62%, and the Chao index by 11.37%, while reducing the Firmicutes/Bacteroidetes ratio by 713.90%. In conclusion, <i>G. alkanivorans</i> enhances immunity and antiviral activity in piglets by gut and immune regulation.