Potential of a yogurt enriched with synbiotics for influenza prevention and treatment

Probiotics show anti-influenza activity, offering a potential variant-resistant alternative for infection prevention and control. In this study, we evaluated whether a  specially formulated yogurt enriched with synbiotics (named yogurt 1 in this study) with seven probiotics and six prebiotics, has anti-influenza effects and its underlying mechanisms using a mouse model challenged with influenza virus H1N1 PR8 strain. The mice were treated with phosphate-buffered saline (negative control), yogurt matrix, yogurt 1, and oseltamivir (positive control), respectively. yogurt 1 treatment improved the survival of infected mice (from 0% to 30%), alleviated pathological injuries in the lungs and colon, and reduced the viral load of influenza virus on days 3 and 7 post-infection. yogurt 1 also downregulated some inflammation-related signaling pathways and reduced the levels of proinflammatory cytokines or chemokines in the lungs or serum, including interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α) and keratinocyte chemoattractant (KC). The levels of short-chain fatty acids in the cecal content were increased, the diversity of the intestinal flora was partially restored, and influenza-specific IgG and interferon-secreting lymphocytes were enhanced following yogurt 1 administration. Thus, yogurt 1, as a commercial and easily accessible dairy product, demonstrated a notable anti-influenza effect in mice by inhibiting viral proliferation, suppressing excessive inflammatory responses, and promoting influenza virus-specific adaptive humoral and cellular immune responses, demonstrating its potential for influenza epidemic prevention and control.