title: Immunization against multidrug-resistant Acinetobacter baumannii effectively protects mice in both pneumonia and sepsis models.
abstract: OBJECTIVE
  Acinetobacter baumannii is considered the prototypical example of a multi- or pan- drug-resistant bacterium. It has been increasingly implicated as a major cause of nosocomial and community-associated infections. This study proposed to evaluate the efficacy of immunological approaches to prevent and treat A. baumannii infections.
  
  
  METHODS
  Mice were immunized with outer membrane vesicles (OMVs) prepared from a clinically isolated multidrug-resistant strain of A. baumannii. Pneumonia and sepsis models were used to evaluate the efficacy of active and passive immunization with OMVs. The probable effective mechanisms and the protective potential of clonally distinct clinical isolates were investigated in vitro using an opsonophagocytic assay.
  
  
  RESULTS
  Intramuscular immunization with OMVs rapidly produced high levels of OMV-specific IgG antibodies, and subsequent intranasal challenge with A. baumannii elicited mucosal IgA and IgG responses. Both active and passive immunization protected the mice from challenges with homologue bacteria in a sepsis model. Bacterial burden in bronchoalveolar lavage fluids (BALF), lung, and spleen, inflammatory cell infiltration in BALF and lung, and inflammatory cytokine accumulation in BALF was significantly suppressed in the pneumonia model by both active and passive immunization strategies. The antisera from immunized mice presented with significant opsonophagocytic activities in a dose-dependent manner against not only homologous strains but also five of the other six clonally distinct clinical isolates.
  
  
  CONCLUSIONS
  Utilizing immunological characteristics of outer membrane proteins to elevate protective immunity and circumvent complex multidrug-resistance mechanisms might be a viable approach to effectively control A. baumannii infections.
authors: Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China; Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Diseases, Kunming, China; Yunnan Engineering Research Center of Vaccine Research and Development on Severe Infectious Diseases, Kunming, China.
authors: Weiwei
authors: W
authors: Huang
authors: Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China; Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Diseases, Kunming, China; Yunnan Engineering Research Center of Vaccine Research and Development on Severe Infectious Diseases, Kunming, China.
authors: Yufeng
authors: Y
authors: Yao
authors: Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China; Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Diseases, Kunming, China; Yunnan Engineering Research Center of Vaccine Research and Development on Severe Infectious Diseases, Kunming, China.
authors: Qiong
authors: Q
authors: Long
authors: Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China; Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Diseases, Kunming, China; Yunnan Engineering Research Center of Vaccine Research and Development on Severe Infectious Diseases, Kunming, China.
authors: Xu
authors: X
authors: Yang
authors: Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China; Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Diseases, Kunming, China; Yunnan Engineering Research Center of Vaccine Research and Development on Severe Infectious Diseases, Kunming, China.
authors: Wenjia
authors: W
authors: Sun
authors: Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China; Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Diseases, Kunming, China; Yunnan Engineering Research Center of Vaccine Research and Development on Severe Infectious Diseases, Kunming, China.
authors: Cunbao
authors: C
authors: Liu
authors: Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China; Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Diseases, Kunming, China; Yunnan Engineering Research Center of Vaccine Research and Development on Severe Infectious Diseases, Kunming, China.
authors: Xiaomei
authors: X
authors: Jin
authors: Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China; Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Diseases, Kunming, China; Yunnan Engineering Research Center of Vaccine Research and Development on Severe Infectious Diseases, Kunming, China.
authors: Yang
authors: Y
authors: Li
authors: Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China; Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Diseases, Kunming, China; Yunnan Engineering Research Center of Vaccine Research and Development on Severe Infectious Diseases, Kunming, China.
authors: Xiaojie
authors: X
authors: Chu
authors: The Second Affiliated Hospital of Kunming Medical University; Kunming, China.
authors: Bin
authors: B
authors: Chen
authors: Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Kunming, China; Yunnan Key Laboratory of Vaccine Research & Development on Severe Infectious Diseases, Kunming, China; Yunnan Engineering Research Center of Vaccine Research and Development on Severe Infectious Diseases, Kunming, China.
authors: Yanbing
authors: Y
authors: Ma
mesh_terms: D000151:Acinetobacter Infections / Q000276:immunology / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000276:immunology* / Q000302:isolation & purification; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology / Q000648:ultrastructure; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D024901:Drug Resistance, Multiple, Bacterial; D007106:Immune Sera / Q000276:immunology; D007114:Immunization; D007070:Immunoglobulin A / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D007249:Inflammation / Q000473:pathology; D008168:Lung / Q000382:microbiology / Q000473:pathology; D051379:Mice; D009895:Opsonin Proteins / Q000378:metabolism; D010587:Phagocytosis; D011014:Pneumonia / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control*; D018805:Sepsis / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control*; D016019:Survival Analysis
chemical_list: D016207:Cytokines; D007106:Immune Sera; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D009895:Opsonin Proteins