Paraliobacillus zengyii CGMCC1.16464 (P. zengyii) is a novel antiviral probiotic candidate strain. To ensure its safety as a potential probiotic, a safety evaluation was conducted in this study. The safety and functional potential of P. zengyii were systematically assessed through genomic bioinformatics analysis, in vitro experiments, and acute oral toxicity tests in mice. Genomic analysis revealed that P. zengyii is rich in genes related to carbohydrate and amino acid metabolisms and carries genes encoding antimicrobial and antiviral agents (such as ectoine, type III polyketide synthase, and lasso peptides). It also expresses gastrointestinal tolerance-related proteins (ClpC, GroEL, and ClpP). Its resistance to polymyxins is an inherent trait with no risk of plasmid-mediated transfer. In vitro experiments confirmed that P. zengyii is somewhat tolerant to bile salts and acidic environments and does not exhibit hemolytic or gelatinase activity. Importantly, an acute oral toxicity test in mice revealed that after intervention with high, medium, or low doses, no significant abnormalities in the body weight, organ index, or tissue morphology of the mice were observed. In conclusion, P. zengyii exhibited good safety and probiotic potential in terms of genomic safety, metabolic function, and in vitro and in vivo toxicities, providing a theoretical basis for the development of novel functional probiotics.

Enterovirus 71 (EV71) is the major causative agent of hand, foot, and mouth disease (HFMD), leading to a serious health threat to young children. Probiotics are effective at treating or preventing gastrointestinal infections, especially viral infections. Probiotics against EV71 are mainly traditional lactic acid-producing bacteria, and most of them have been proven to be effective only in vitro. Here, we report that the marine bacterium Paraliobacillus zengyii X-1125 (P. zengyii) has promising anti-EV71 activity. The antiviral effect of P. zengyii against EV71 was assessed in different cell lines, and the viral RNA levels and titers were obviously reduced after treatment with P. zengyii. Furthermore, we established an EV71-infected mouse model to evaluate its antiviral efficacy in vivo. The oral administration of P. zengyii significantly decreased the viral loads in the hindlimb muscles, spleens, and ileums. Further research revealed that P. zengyii enhances the expression of type I interferon (IFN-I) in EV71-infected cells. Similarly, transcriptome analysis indicated that the expression of interferon-stimulated genes (ISGs) in EV71-infected mice significantly increased after P. zengyii treatment. Taken together, the results of this study indicated that P. zengyii markedly reduces EV71 infection by regulating the IFN response both in vivo and in vitro, providing a potential means to work against EV71 infection.

Osteosarcoma primarily occurs in children and adolescents, and is a highly aggressive bone tumor, particularly presenting challenges in metastatic or recurrent cases due to chemoresistance. Emerging evidences suggest that histone deacetylase inhibitors (HDACis) may exert anti-tumor effects by enhancing the efficacy of various therapeutic modalities. However, the combination of traditional chemotherapy with HDACi-based treatment for osteosarcoma intervention has not been thoroughly explored. This study investigates the anticancer properties of HDACis and/or etoposide (VP16) on the osteosarcoma cell lines U2OS and SJSA-1. Cell viability, morphology, growth and apoptosis were evaluated after treatments, in addition to their influence on the expression levels of proteins associated with apoptotic processes. To elucidate the underlying mechanisms, we employed RNA sequencing, RT-qPCR, and Western blot analyses. Treatment with either HDACis or VP16 alone resulted in an antiproliferative effects in U2OS and SJSA-1 cell lines. Notably, HDACis significantly increased the sensitivity of osteosarcoma cells to VP16, as evidenced by marked differences in cell viability, growth, morphology and apoptosis. Furthermore, when compared to doxorubicin treatment, this VP16/TSA/NAM combinatory regimen demonstrated a comparable ability to suppress cell viability while exhibiting a more pronounced inhibition of cell proliferation. Mechanistically, the combination of HDACis and VP16 specifically resulted in inhibition of the Hippo/YAP signaling cascade, accompanied by a reduction in total YAP1 protein expression. Collectively, our findings suggest that HDACis potentiate the capacity of VP16 to hinder cellular proliferation and trigger apoptosis via the downregulation of the Hippo/YAP pathway, thereby providing a prospective approach to overcome chemoresistance in osteosarcoma.