Immunogenic potential of 65.5 kDa pili protein of <i>Klebsiella pneumoniae</i>: Evaluation of IgG, IgG1, and IgG2a levels in BALB/c mice

Dini Agustina; Diana Chusna Mufida; Yunita Armiyanti; M. Ali Shodikin; Enny Suswati; Muhammad Farhan Hibatulloh; Shafrizal Aufal Ikhsani; Virly Kania Mitananda; Priska Liana Lutianto; Dini Agustina; Diana Chusna Mufida; Yunita Armiyanti; M. Ali Shodikin; Enny Suswati; Muhammad Farhan Hibatulloh; Shafrizal Aufal Ikhsani; Virly Kania Mitananda; Priska Liana Lutianto

doi:10.3934/Allergy.2025011

AIMS Allergy and Immunology

2025, Volume 9, Issue 3: 144-155. doi: 10.3934/Allergy.2025011

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Research article

Immunogenic potential of 65.5 kDa pili protein of Klebsiella pneumoniae: Evaluation of IgG, IgG1, and IgG2a levels in BALB/c mice

1.
Departement of Microbiology, Faculty of Medicine, University of Jember, East Java, Kalimantan Street No.37, 68121, Indonesia
2.
Departement of Parasitology, Faculty of Medicine, University of Jember, East Java, Kalimantan Street No.37, 68121, Indonesia
3.
Undergraduate of Faculty of Medicine, University of Jember, East Java, Kalimantan Street No.37, 68121, Indonesia

Received: 30 January 2025 Revised: 29 May 2025 Accepted: 06 June 2025 Published: 27 June 2025

Klebsiella pneumoniae is a significant etiological agent of both community-acquired and nosocomial infections, characterized by its pronounced vulnerability to drug resistance. Preventive measures, such as vaccine research, are essential since no effective and viable vaccine currently exists. Pili, a critical virulence component in Klebsiella pneumoniae, promote bacterial adherence and have very low variability relative to other virulence factors, rendering them a viable target for vaccination. The 65.5 kDa pili protein has been recognized as a possible antigen owing to its significant antigenicity. This study sought to assess the immunogenic response by quantifying IgG, IgG1, and IgG2a levels in BALB/c mice following the delivery of the 65.5 kDa pili protein. A total of 24 mice were categorized into three groups: PBS, adjuvant, and pili. Serum concentrations of IgG, IgG1, and IgG2a were assessed via ELISA. Statistical analysis was conducted utilizing the ANOVA test with a 95% confidence interval. The data indicate that vaccination with the 65.5 kDa pili protein elicits a robust humoral immune response characterized by increased IgG and IgG1 production, suggesting a Th2-biased response, while showing no significant impact on IgG2a levels, which are typically associated with Th1-mediated immunity. In summary, the 65.5 kDa pili protein shows promise as a vaccine candidate for Klebsiella pneumoniae by inducing a strong IgG and IgG1-mediated immunological response in BALB/c mice. Future studies should use flow cytometry to assess immune cell activation, cytokine profiling for Th1/Th2 responses, and antigen-specific assays to explore T-cell activation. Research on dose optimization, adjuvant screening, immunity duration, and challenge studies with virulent Klebsiella pneumoniae is crucial. Proteomic analysis and epitope mapping can aid in refining vaccine design.
- antigen,
- immunoglobulin-G,
- immunoglobulin G1,
- immunoglobulin G2a,
- Klebsiella pneumonia,
- mice,
- pili,
- vaccine
Citation: Dini Agustina, Diana Chusna Mufida, Yunita Armiyanti, M. Ali Shodikin, Enny Suswati, Muhammad Farhan Hibatulloh, Shafrizal Aufal Ikhsani, Virly Kania Mitananda, Priska Liana Lutianto. Immunogenic potential of 65.5 kDa pili protein of Klebsiella pneumoniae: Evaluation of IgG, IgG1, and IgG2a levels in BALB/c mice[J]. AIMS Allergy and Immunology, 2025, 9(3): 144-155. doi: 10.3934/Allergy.2025011

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Abstract

Klebsiella pneumoniae is a significant etiological agent of both community-acquired and nosocomial infections, characterized by its pronounced vulnerability to drug resistance. Preventive measures, such as vaccine research, are essential since no effective and viable vaccine currently exists. Pili, a critical virulence component in Klebsiella pneumoniae, promote bacterial adherence and have very low variability relative to other virulence factors, rendering them a viable target for vaccination. The 65.5 kDa pili protein has been recognized as a possible antigen owing to its significant antigenicity. This study sought to assess the immunogenic response by quantifying IgG, IgG1, and IgG2a levels in BALB/c mice following the delivery of the 65.5 kDa pili protein. A total of 24 mice were categorized into three groups: PBS, adjuvant, and pili. Serum concentrations of IgG, IgG1, and IgG2a were assessed via ELISA. Statistical analysis was conducted utilizing the ANOVA test with a 95% confidence interval. The data indicate that vaccination with the 65.5 kDa pili protein elicits a robust humoral immune response characterized by increased IgG and IgG1 production, suggesting a Th2-biased response, while showing no significant impact on IgG2a levels, which are typically associated with Th1-mediated immunity. In summary, the 65.5 kDa pili protein shows promise as a vaccine candidate for Klebsiella pneumoniae by inducing a strong IgG and IgG1-mediated immunological response in BALB/c mice. Future studies should use flow cytometry to assess immune cell activation, cytokine profiling for Th1/Th2 responses, and antigen-specific assays to explore T-cell activation. Research on dose optimization, adjuvant screening, immunity duration, and challenge studies with virulent Klebsiella pneumoniae is crucial. Proteomic analysis and epitope mapping can aid in refining vaccine design.

Acknowledgments

We extend our profound appreciation to Ms. Lilis for her indispensable support as the microbiology laboratory technician, facilitating the seamless execution of all laboratory operations. We extend our sincere gratitude to Ms. Lilik for her meticulous oversight of the mouse housing and killing procedures. We express our profound gratitude to Ms. Nuris for her assistance and competence as the biochemistry and biotechnology laboratory technician, which has greatly contributed to the accomplishment of our research. Your commitment and efforts were vital to the completion of this study.

Conflict of interest

The authors declare no conflict of interest.

Author contributions

All authors made substantial contributions to the research. Dini Agustina was accountable for ideation, methodological design, data collection, analysis, paper preparation, and final endorsement. Diana Chusna offered oversight, project management, thorough text evaluation, and final endorsement. Yunita Armiyanti facilitated resource procurement, oversaw laboratory operations, and ensured data verification. M. Ali Shodikin conducted statistical analysis, interpreted data, and performed critical article review. Enny Suswati offered oversight, help on experimental design, and manuscript editing. Muhammad Farhan Hibatulloh participated in experimental protocols, data acquisition, and preliminary data analysis. Shafrizal Aufal Ikhsani provided assistance with laboratory activities, sample processing, and technical support. Virly Kania Mitananda executed laboratory experiments, data input, and preliminary analysis, whilst Priska Liana Lutianto oversaw data organization, did the literature review, and edited the report. All authors reviewed and endorsed the final version of the text.

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