Broad-Spectrum Protective Efficacy of a Fully Human Antibody Cocktail Targeting PcrV, ETA, and PA0833 Against Pseudomonas aeruginosa Infection.

Pseudomonas aeruginosa (P. aeruginosa) pose a global health threat, with carbapenem-resistant strains in particular posing a grave threat due to high mortality rates and limited treatment options for antibiotic-refractory infections. To address the inherent limitations of single-target therapies, this study developed a multi-target fully human monoclonal antibody (mAb) cocktail targeting three core virulence factors: a key component of the type III secretion system, exotoxin A, and an outer membrane protein. Using a fully human transgenic mouse platform, we generated and characterized three high-affinity mAbs targeting PcrV (U0151, Kd = 2.69 nM), ETA (U0462, Kd = 1.75 nM), and PA0833 (U0057, Kd = 0.34 nM). Functional assays confirmed robust target-specific activities, including neutralization of PcrV-mediated hemolysis, inhibition of ETA-induced cytotoxicity, and enhancement of cell-mediated bacterial clearance. In mouse models of systemic infection and acute pneumonia caused by PAO1, a significant enhancement in efficacy was observed when three types of antibodies were used in combination, increasing protective rates to 78% and 88%, respectively, whereas monotherapies achieved protective rates of no more than 38%. Combined treatment also reduced bacterial burden, alleviated tissue damage, and suppressed excessive neutrophil infiltration. Furthermore, it showed immune protection against several clinical isolates of P. aeruginosa, including carbapenem-resistant strains, within these limits, the data support the three-antibody combination as a candidate adjunctive immunotherapy for multidrug-resistant P. aeruginosa infection.