A monoclonal antibody raised against Acinetobacter baumannii capsular carbohydrate exhibits cross-species in vitro binding against Pseudomonas aeruginosa

The emergence of extensively drug-resistant bacterial pathogens such as Acinetobacter baumannii and Pseudomonas aeruginosa necessitates the innovation of non-small molecule therapies. Monoclonal antibodies represent a promising non-small molecule option. By exploiting shared or similar antigenic structures on these pathogens, it may be possible to develop therapeutic antibodies that target both bacterial species. Here we demonstrate that a previously developed monoclonal antibody targeting A. baumannii (MAb10) has cross-species reactivity to P. aeruginosa in in vitro assays. Despite MAb10's distinct efficacy against A. baumannii, no efficacy was detected against P. aeruginosa in our mouse models of infection. Nevertheless, the unique carbohydrate structures targeted by MAb10 and shared by numerous bacterial species may underscore a possible strategy for developing therapeutic antibodies that can treat infections caused by multiple pathogens.