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Antibody-guided identification of Achromobacter xylosoxidans protein antigens in cystic fibrosis.

Sahl, Cecilia LU orcid ; Chowdhury, Sounak LU ; Malmström, Johan LU orcid and Påhlman, Lisa I LU (2025) In mSphere p.1-14
Abstract

Persistent bacterial airway infection is a hallmark feature of cystic fibrosis (CF). Achromobacter spp. are gram-negative rods that can cause persistent airway infection in people with CF (pwCF), but the knowledge of host immune responses to these bacteria is limited. The aim of this study was to investigate if patients develop antibodies against Achromobacter xylosoxidans, the most common Achromobacter species, and to identify the bacterial antigens that induce specific IgG responses. Seven serum samples from pwCF with Achromobacter infection were screened for antibodies against bacteria in an ELISA coated with A. xylosoxidans, A. insuavis, or Pseudomonas aeruginosa. Sera from pwCF with or without P. aeruginosa infection ( n =... (More)

Persistent bacterial airway infection is a hallmark feature of cystic fibrosis (CF). Achromobacter spp. are gram-negative rods that can cause persistent airway infection in people with CF (pwCF), but the knowledge of host immune responses to these bacteria is limited. The aim of this study was to investigate if patients develop antibodies against Achromobacter xylosoxidans, the most common Achromobacter species, and to identify the bacterial antigens that induce specific IgG responses. Seven serum samples from pwCF with Achromobacter infection were screened for antibodies against bacteria in an ELISA coated with A. xylosoxidans, A. insuavis, or Pseudomonas aeruginosa. Sera from pwCF with or without P. aeruginosa infection ( n = 22 and 20, respectively) and healthy donors ( n = 4) were included for comparison. Serum with high titers to A. xylosoxidans was selected for affinity purification of bacterial antigens using serum IgGs bound to protein G beads. The resulting IgG-antigen complexes were then analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Selected antigens of interest were produced in recombinant form and used in an ELISA to confirm the results. Four of the seven patients with Achromobacter infection had serum antibodies against Achromobacter. Using patient serum-IgG for affinity purification of A. xylosoxidans proteins, we identified eight antigens. Three of these, which were not targeted by anti- P. aeruginosa antibodies, were expressed recombinantly for further validation: dihydrolipoyl dehydrogenase (DLD), type I secretion C-terminal target domain-containing protein, and domain of uncharacterized function 336 (DUF336). While specific IgG against all three recombinant antigens was confirmed in the patient serum with high titers against Achromobacter, DLD and DUF336 showed the least binding to serum IgG from pwCF without Achromobacter spp. infection. Using serum IgG affinity purification in combination with LC-MS/MS and confirming the results using ELISA against recombinant proteins, we have identified bacterial antigens from A. xylosoxidans.IMPORTANCE Achromobacter species are opportunistic pathogens that can cause airway infections in people with cystic fibrosis. In this patient population, persistent Achromobacter infection is associated with low lung function, but the knowledge about bacterial interactions with the host is currently limited. In this study, we identify protein antigens that induce specific antibody responses in the host. The identified antigens may potentially be useful in serological assays, serving as a complement to culturing methods for the diagnosis and surveillance of Achromobacter infection.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
epub
subject
in
mSphere
article number
e0023325
pages
1 - 14
publisher
American Society for Microbiology
external identifiers
  • pmid:40298413
ISSN
2379-5042
DOI
10.1128/msphere.00233-25
language
English
LU publication?
yes
id
6ff1484a-1ae7-4640-b99c-327a82327329
date added to LUP
2025-05-01 10:03:03
date last changed
2025-05-05 08:03:57
@article{6ff1484a-1ae7-4640-b99c-327a82327329,
  abstract     = {{<p>Persistent bacterial airway infection is a hallmark feature of cystic fibrosis (CF).  Achromobacter spp. are gram-negative rods that can cause persistent airway infection in people with CF (pwCF), but the knowledge of host immune responses to these bacteria is limited. The aim of this study was to investigate if patients develop antibodies against  Achromobacter xylosoxidans, the most common  Achromobacter species, and to identify the bacterial antigens that induce specific IgG responses. Seven serum samples from pwCF with  Achromobacter infection were screened for antibodies against bacteria in an ELISA coated with A. xylosoxidans,  A. insuavis, or  Pseudomonas aeruginosa. Sera from pwCF with or without  P. aeruginosa infection ( n = 22 and 20, respectively) and healthy donors ( n = 4) were included for comparison. Serum with high titers to  A. xylosoxidans was selected for affinity purification of bacterial antigens using serum IgGs bound to protein G beads. The resulting IgG-antigen complexes were then analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Selected antigens of interest were produced in recombinant form and used in an ELISA to confirm the results. Four of the seven patients with  Achromobacter infection had serum antibodies against  Achromobacter. Using patient serum-IgG for affinity purification of  A. xylosoxidans proteins, we identified eight antigens. Three of these, which were not targeted by anti- P.  aeruginosa antibodies, were expressed recombinantly for further validation: dihydrolipoyl dehydrogenase (DLD), type I secretion C-terminal target domain-containing protein, and domain of uncharacterized function 336 (DUF336). While specific IgG against all three recombinant antigens was confirmed in the patient serum with high titers against Achromobacter, DLD and DUF336 showed the least binding to serum IgG from pwCF without Achromobacter spp. infection. Using serum IgG affinity purification in combination with LC-MS/MS and confirming the results using ELISA against recombinant proteins, we have identified bacterial antigens from  A. xylosoxidans.IMPORTANCE Achromobacter species are opportunistic pathogens that can cause airway infections in people with cystic fibrosis. In this patient population, persistent  Achromobacter infection is associated with low lung function, but the knowledge about bacterial interactions with the host is currently limited. In this study, we identify protein antigens that induce specific antibody responses in the host. The identified antigens may potentially be useful in serological assays, serving as a complement to culturing methods for the diagnosis and surveillance of  Achromobacter infection. </p>}},
  author       = {{Sahl, Cecilia and Chowdhury, Sounak and Malmström, Johan and Påhlman, Lisa I}},
  issn         = {{2379-5042}},
  language     = {{eng}},
  month        = {{04}},
  pages        = {{1--14}},
  publisher    = {{American Society for Microbiology}},
  series       = {{mSphere}},
  title        = {{Antibody-guided identification of Achromobacter xylosoxidans protein antigens in cystic fibrosis.}},
  url          = {{http://dx.doi.org/10.1128/msphere.00233-25}},
  doi          = {{10.1128/msphere.00233-25}},
  year         = {{2025}},
}