Identification of broadly protective human antibodies to Pseudomonas aeruginosa exopolysaccharide Psl by phenotypic screening.
Pseudomonas aeruginosa is a leading cause of hospital-associated infections in the seriously ill, and the primary agent of chronic lung infections in cystic fibrosis patients. A major obstacle to effective control of P. aeruginosa infections is its intrinsic resistance to most antibiotic classes, which results from chromosomally encoded drug-efflux systems and multiple acquired resistance mechanisms selected by years of aggressive antibiotic therapy. These factors demand new strategies and drugs to prevent and treat P. aeruginosa infections. Herein, we describe a monoclonal antibody (mAb) selection strategy on whole P. aeruginosa cells using single-chain variable fragment phage libraries derived from healthy individuals and patients convalescing from P. aeruginosa infections. This approach enabled identification of mAbs that bind three distinct epitopes on the product of the Psl. This exopolysaccharide is important for P. aeruginosa attachment to mammalian cells, and for the formation and maintenance of biofilms produced by nonmucoid and mucoid P. aeruginosa isolates. Functional screens revealed that mAbs to one epitope exhibit superior activity in opsonophagocytic killing and cell attachment assays, and confer significant protection in multiple animal models. Our results indicate that Psl is an accessible serotype-independent surface feature and promising novel protective antigen for preventing P. aeruginosa infections. Furthermore, our mAb discovery strategy holds promise for application to other bacterial pathogens.
Department of Infectious Diseases, MedImmune, LLC, Gaithersburg, MD 20878, USA.
Antonio
A
DiGiandomenico
Paul
P
Warrener
Melissa
M
Hamilton
Sandrine
S
Guillard
Peter
P
Ravn
Ralph
R
Minter
Maria Margarita
MM
Camara
Vignesh
V
Venkatraman
Randall S
RS
Macgill
Jia
J
Lin
Qun
Q
Wang
Ashley Elaine
AE
Keller
Jessica C
JC
Bonnell
Mladen
M
Tomich
Lutz
L
Jermutus
Michael P
MP
McCarthy
David A
DA
Melnick
Joann A
JA
Suzich
C Kendall
CK
Stover
D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D001422:Bacterial Adhesion / Q000187:drug effects / Q000276:immunology; D045744:Cell Line, Tumor; D006801:Humans; D053208:Kaplan-Meier Estimate; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D050296:Microbial Viability / Q000187:drug effects / Q000276:immunology; D009154:Mutation; D019151:Peptide Library; D011014:Pneumonia / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000276:immunology* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000235:genetics / Q000276:immunology*; D012703:Serotyping; D057127:Single-Chain Antibodies / Q000235:genetics / Q000276:immunology
D000911:Antibodies, Monoclonal; D019151:Peptide Library; D011135:Polysaccharides, Bacterial; D057127:Single-Chain Antibodies; C064841:exopolysaccharide, Pseudomonas