High-throughput single-cell analysis reveals Omp38-specific monoclonal antibodies that protect against <i>Acinetobacter baumannii</i> infection

Infections caused by <i>Acinetobacter baumannii</i> (<i>A. baumannii</i>) have emerged as a global public health concern because of high pathogenicity of this bacterium. Monoclonal antibodies (mAbs) have a lower likelihood of promoting drug resistance and offer targeted treatment, thereby reducing potential adverse effects; however, the therapeutic potential of mAbs targeting A. baumannii has not been fully characterized. In this study, mAbs against the outer membrane proteins (OMPs) of <i>A. baumannii</i> were isolated in a high-throughput manner. The ability of Omp38-specific mAbs to bind to <i>A. baumannii</i> strains from diverse sources was confirmed via enzyme-linked immunosorbent assay (ELISA). Intravenous administration of the Omp38-specific mAbs significantly improved the survival rate and reduced the bacterial load in a mouse model of lethal A. baumannii infection. Flow cytometry and ELISA confirmed that immune cell infiltration and cytokine production, respectively, decreased in a mouse model of sublethal <i>A. baumannii</i> infection. In addition, analysis of the Omp38-mAb C3 binding conformation revealed the potential mechanism of broad-spectrum binding activity of this mAb against <i>A. baumannii</i>. Taken together, these findings indicate that mAbs against Omp38 facilitate bacterial clearance from host, minimize inflammatory mediator release and reduce host damage, highlighting the potential of Omp38-specific mAbs in the clinical treatment of <i>A. baumannii</i> infection.