Identification of protective B cell antigens of Legionella pneumophila.
Abs confer protection from secondary infection with Legionella pneumophila, the causative agent of a severe form of pneumonia known as Legionnaires' disease. In this study, we demonstrate that Ab-mediated protection is effective across L. pneumophila serogroups, suggesting that Abs specific for conserved protein Ags are sufficient to mediate this protective effect. We used two independent methods to identify immunogenic L. pneumophila protein Ags, namely, the screening of a λ phage library representing the complete L. pneumophila genome and two-dimensional gel electrophoresis combined with Western blot analysis and protein spot identification by mass spectrometry. A total of 30 novel L. pneumophila B cell Ags were identified, the majority of which are located in or associated with the bacterial membrane, where they are accessible for Abs and, therefore, likely to be relevant for Ab-mediated protection against L. pneumophila. Selected B cell Ags were recombinantly expressed and tested in a vaccination protocol. Mice immunized with either single-protein Ags or an Ag combination showed reduced bacterial titers in bronchoalveolar lavage and lung after L. pneumophila challenge. To determine the clinical relevance of these findings, we tested Legionnaires' disease patient sera for reactivity with the identified L. pneumophila Ags. The recognized Ags were indeed conserved across host species, because Abs specific for all three selected Ags could be detected in patient sera, rendering the identified protein Ags potential vaccine candidates.
Institute of Microbiology, Swiss Federal Institute of Technology, Zurich, CH-8093 Zurich, Switzerland.
Stefan S
SS
Weber
Nicole
N
Joller
Anna Barbara
AB
Küntzel
Roman
R
Spörri
Vincent S
VS
Tchang
Elke
E
Scandella
Christoph
C
Rösli
Burkhard
B
Ludewig
Hubert
H
Hilbi
Annette
A
Oxenius
D000281:Administration, Intranasal; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000097:blood / Q000627:therapeutic use; D000942:Antigens, Bacterial / Q000008:administration & dosage / Q000276:immunology / Q000302:isolation & purification*; D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000138:chemical synthesis / Q000276:immunology; D010582:Bacteriophage lambda / Q000235:genetics / Q000276:immunology; D017124:Conserved Sequence / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000097:blood; D016952:Legionella pneumophila / Q000276:immunology* / Q000472:pathogenicity; D007877:Legionnaires' Disease / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology / Q000627:therapeutic use
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001428:Bacterial Vaccines; D007074:Immunoglobulin G; D014614:Vaccines, Synthetic