Influenza A virus (IAV) infection is a global public health concern. It causes respiratory diseases ranging from mild illness to fatal disease. Natural killer (NK) cells are an innate immune component that kill infected cells and secrete cytokines to modulate the adaptive immune system; they constitute the first-line defense and play important roles in controlling IAV infection. This study evaluated the effect of daily administration of heat-treated Lactobacillus plantarum nF1-fortified yogurt on immunity and protection against IAV infection. Mice administered with heat-treated L. plantarum nF1-fortified yogurt showed elevated NK cell-related cytokine expression levels. Daily administration of the L. plantarum nF1-fortified yogurt before IAV infection also enhanced splenic NK activity, lung inflammatory cytokine responses, and survival rate. Thus, daily administration of nF1-fortified yogurt enhances host immunity and helps prevent IAV infection.

甲型流感病毒（IAV）感染是全球公共卫生关注的问题。它会导致呼吸系统疾病，从轻度疾病到致命疾病。天然杀伤（NK）细胞是一种先天性免疫成分，可以杀死受感染的细胞并分泌细胞因子来调节适应性免疫系统。它们构成了一线防御，并在控制IAV感染中发挥重要作用。这项研究评估了每天服用热处理过的植物乳杆菌nF1强化酸奶对免疫和抵抗IAV感染的影响。给予经热处理的植物乳杆菌nF1强化酸奶的小鼠显示出升高的NK细胞相关细胞因子表达水平。植物乳杆菌的日常管理在IAV感染前用nF1强化的酸奶还可以增强脾脏NK活性，肺炎性细胞因子反应和存活率。因此，每天服用nF1强化的酸奶可以增强宿主的免疫力，并有助于预防IAV感染。