PI3 and viral infectious disease: Based on the gene screening in the above research results and by using the Limma package (16) to perform differential expression gene analysis on the GSE277828, GSE72849 and GSE40396 datasets in the GEO database, three potential host genes were finally screened in this study: interferon-induced protein 44-like (IFI44L), peptidase inhibitor 3 (PI3) and integrin subunit beta 2 (ITGB2), and attempted to investigate their value in differentiating bacterial and viral infections in UC-OI.