Antiviral Potential of Selenium-Enriched Bacillus pumilus : Inhibition of PCV2 Replication via Alleviation of Oxidative Stress

Aims In recent years, porcine circovirus type 2 (PCV2) has emerged as one of the most economically significant viral pathogens affecting the global swine industry, leading to substantial economic losses. Accumulating evidence indicates that oxidative stress facilitates PCV2 infection and replication, whereas alleviating oxidative stress can attenuate this process. Notably, glutathione and selenium play pivotal roles in the antioxidant response. Accordingly, we selected a glutathione-producing strain of Bacillus pumilus for selenium enrichment and investigated its inhibitory effects on PCV2 replication. This study aims to provide experimental evidence for the development of microecological preparations with antiviral activity. Methods and Results In this study, microbial colony counting, analysis of the biological characteristics of bacteria, histopathological analysis, biochemical indicator analysis, quantitative real-time PCR, and Western blotting were used to evaluate the effects of the selenium-enriched Bacillus pumilus composite probiotic on PCV2 replication in a mouse model. The results demonstrated that this Bacillus pumilus strain exhibited high glutathione production, favorable biological characteristics, and strong selenium-enriching capacity. The composite probiotic preparation modulated the JAK/STAT signaling pathway and elevated the phosphorylation levels of JAK1, STAT1, and STAT2. This further upregulated the expression of key antiviral effector genes Mx1 and Oas1 in the mouse spleen, thereby inhibiting PCV2 replication in vivo. Conclusions In this study, selenium-enriched, glutathione-producing Bacillus pumilus exhibits antiviral potential. It suppresses in vivo PCV2 replication via alleviating oxidative stress, which provides the theoretical basis and experimental support for the development of novel antiviral microecological preparations.