Effect of Engineered EcN-IFN-α2b on Human Papillomavirus Persistence in an NSG Surrogate Model

Currently, live biotherapeutic products (LBP) have been widely used to improve gut microbiota, enhance immunity, and promote digestion. Engineering bacteria, as one form of LBP, have made breakthrough progress in the treatment of diseases, but their effectiveness and specific mechanisms in treating vaginal infections are not clear. Here, we innovatively constructed Escherichia coli Nissle 1917-attB-IFN-α2b (EcN-IFN-α2b) expressing antiviral interferon alpha-2b (IFN-α2b) using genome integration technology, and evaluated its ability to reduce human papillomavirus (HPV) viral load and the underlying mechanisms in an NSG mouse surrogate model of HPV. Our results showed that EcN-IFN-α2b had good growth performance, acid resistance, antioxidant ability, and antimicrobial activity in vitro. EcN-IFN-α2b also significantly reduced the HPV viral load (M vs. EcN-IFN-α2b = 1.003 vs. 0.643, p < 0.01), and effectively alleviated the levels of interleukin 1β (IL-1β) (M vs. EcN-IFN-α2b, p < 0.01), interleukin 6 (IL-6) (M vs. EcN-IFN-α2b, p < 0.01), and tumor necrosis factor α (TNF-α) (M vs. EcN-IFN-α2b, p < 0.05) in the vagina. Further mechanistic studies suggested that EcN-IFN-α2b may reduce HPV viral load by activating the JAK/STAT/cGAS/STING signaling pathway. Additionally, we found that EcN-IFN-α2b altered the composition of vaginal microbiota, especially the relative abundance of vaginal pathogens such as Vibrionaceae_Vibrio, Streptococcus, and Staphylococcaceae_Staphylococcus, and the relative abundance of beneficial Lactobacillus. This study systematically evaluated the effects of the novel engineered strain EcN-IFN-α2b in reducing HPV viral load, alleviating associated inflammation, and restoring vaginal microbiota in an NSG mouse surrogate model, providing a new strategy for the future clinical treatment of HPV infection.