Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Feb 12;16(1):2307067.
doi: 10.1080/20002297.2024.2307067. eCollection 2024.

Secretome analysis and virulence assessment in Abiotrophia defectiva

Radhika G Bhardwaj  1 , Mai E Khalaf  2 , Maribasappa Karched  1
Affiliations

Secretome analysis and virulence assessment in Abiotrophia defectiva

Radhika G Bhardwaj et al. J Oral Microbiol. .

Abstract

Background: Abiotrophia defectiva, although infrequently occurring, is a notable cause of culture-negative infective endocarditis with limited research on its virulence. Associated with oral infections such as dental caries, exploring its secretome may provide insights into virulence mechanisms. Our study aimed to analyze and characterize the secretome of A. defectiva strain CCUG 27639.

Methods: Secretome of A. defectiva was prepared from broth cultures and subjected to mass spectrometry and proteomics for protein identification. Inflammatory potential of the secretome was assessed by ELISA.

Results: Eighty-four proteins were identified, with diverse subcellular localizations predicted by PSORTb. Notably, 20 were cytoplasmic, 12 cytoplasmic membrane, 5 extracellular, and 9 cell wall-anchored proteins. Bioinformatics tools revealed 54 proteins secreted via the 'Sec' pathway and 8 via a non-classical pathway. Moonlighting functions were found in 23 proteins, with over 20 exhibiting potential virulence properties, including peroxiredoxin and oligopeptide ABC transporter substrate-binding protein. Gene Ontology and KEGG analyses categorized protein sequences in various pathways. STRING analysis revealed functional protein association networks. Cytokine profiling demonstrated significant proinflammatory cytokine release (IL-8, IL-1β, and CCL5) from human PBMCs.

Conclusions: Our study provides a comprehensive understanding of A. defectiva's secretome, laying the foundation for insights into its pathogenicity.

Keywords: Abiotrophia defectiva; infective endocarditis; oral infections; proteomics; secretome.

PubMed Disclaimer

Conflict of interest statement

No potential conflict of interest was reported by the authors.

Figures

Figure 1.
Figure 1.
Analysis of the proteome of A. defectiva secretome. (a) SDS-PAGE gel showing protein bands from secretome/extracellular proteins (ECP) and whole cell protein preparations (WCP). (b) Protein sequences from LC-MS analysis of the secretome were analyzed by an in silico 2DE tool and (c) Western blot analysis showing the absence of the cytoplasmic marker protein FtsZ in the secretome and whole cell protein preparations.
Figure 2.
Figure 2.
Gene ontology analysis of A. defectiva secreted proteins. Gene ontology annotation was achieved using Blast2GO and an online software ‘WEGO’. Protein sequences were grouped into 3 categories based on their properties and functions.
Figure 3.
Figure 3.
KEGG pathway analysis of the A. defectiva secretome. all protein sequences from the secretome were analyzed by KEGG pathway tool.
Figure 4.
Figure 4.
Functional protein association networks of A. defectiva secretome. The online tool STRING was used for grouping the secreted proteins on the basis of functional networks. Minimum interaction scores were set at a strong confidence level of 0.7. The three major network groups formed are shown in dotted circles. Seven different colored link a number of nodes and represent seven types of evidence used in predicting associations. A red line indicates the presence of fusion evidence; a green line represents neighborhood evidence; a blue line represents co-occurrence evidence; a purple line represents experimental evidence; a yellow line represents text mining evidence; a light blue line represents database evidence and a black line represents co-expression evidence.
Figure 5.
Figure 5.
Cytokine induction from human PBMCs by A. defectiva secretome preparation.
See this image and copyright information in PMC

References

    1. Chowdhury S, German ML.. Rare but not infrequent: infective endocarditis caused by Abiotrophia defectiva. Case Rep Infect Dis. 2018;2018:5186520. doi: 10.1155/2018/5186520 - DOI - PMC - PubMed
    1. Cerceo E, Christie JD, Nachamkin I, et al. Central nervous system infections due to Abiotrophia and granulicatella species: an emerging challenge? Diagn Microbiol Infect Dis. 2004;48(3):161–14. doi: 10.1016/j.diagmicrobio.2003.10.009 - DOI - PubMed
    1. Escarcega E, Trovato C, Idahosa O, et al. Abiotrophia defectiva Endocarditis: An Easy Miss. Clin Pract Cases Emerg Med. 2017;1(3):229–231. doi: 10.5811/cpcem.2017.3.33126 - DOI - PMC - PubMed
    1. Birlutiu V, Birlutiu RM. Endocarditis due to abiotrophia defectiva, a biofilm-related infection associated with the presence of fixed braces: a case report. Medicine (Baltimore). 2017;96(46):e8756. doi: 10.1097/MD.0000000000008756 - DOI - PMC - PubMed
    1. Rhodes HM, Hirigoyen D, Shabnam L, et al. Infective endocarditis due to abiotrophia defectiva and granulicatella spp. complicated by infectious intracranial cerebral aneurysms: a report of three cases and review of the literature. J Med Microbiol. 2016;65(6):493–9. doi: 10.1099/jmm.0.000260 - DOI - PubMed