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Updated: Feb 6, 2026
Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae
Published on: January 17, 2014
Streptococcus pneumoniae surface adhesin PfbA and its interaction with erythrocytes and hemoglobin
Deepthi Radhakrishnan1, Masaya Yamaguchi2, Shigetada Kawabata2
1Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai 600 025, India.
Abstract:
Streptococcus pneumoniae is one of the major colonizers of human nasopharynx and its surface protein PfbA interacts with host molecules like plasmin(ogen), fibrinogen and fibronectin for colonization. Most of the binding partners of PfbA are glycoproteins. Recently we found that PfbA exhibited high affinity towards carbohydrates. It was reported that S. pneumoniae invades erythrocytes and utilizes them to evade human innate immunity. The results of this study suggested that LPXTG motif containing pneumococcal surface proteins, erythrocyte lipid rafts and erythrocyte actin remodeling are all involved in the invasion mechanism. The erythrocyte cell membrane contains different glycoproteins and glycolipids. Therefore, to find out if PfbA plays any role in erythrocyte binding, we carried out the binding studies of rPfbA49-684 with human red blood cells (RBCs) especially with its surface molecules employing ELISA and Bio Layer Interferometry. The results from these experiments show that rPfbA49-684 has a broad specificity for carbohydrates and remarkable affinity towards RBCs and in particular with extracted surface glycolipids. Further rPfbA49-684 also exhibited moderate affinity towards hemoglobin. Thus the results of the present study provide clear evidence that PfbA can interact with RBCs and this could be one of the important factors in erythrocyte invasion of S. pneumoniae.
Insights
Streptococcus pneumoniae surface protein PfbA binds to human red blood cells (RBCs), particularly their glycolipids. This interaction is a key factor in pneumococcal invasion of erythrocytes, aiding immune evasion.
Area of Science:
- Microbiology
- Molecular Biology
- Immunology
Background:
- Streptococcus pneumoniae colonizes the human nasopharynx, utilizing surface protein PfbA to bind host molecules for colonization.
- PfbA primarily interacts with glycoproteins, but recent findings indicate a high affinity for carbohydrates.
- S. pneumoniae invades erythrocytes to evade the host's innate immune system, involving pneumococcal surface proteins and erythrocyte components.
Purpose of the Study:
- To investigate the role of Streptococcus pneumoniae surface protein PfbA in binding to human red blood cells (RBCs).
- To determine if PfbA interacts with specific molecules on the RBC surface, including glycolipids and hemoglobin.
Main Methods:
- Binding studies were conducted using recombinant PfbA (rPfbA49-684) and human RBCs.
- Enzyme-Linked Immunosorbent Assay (ELISA) and Bio-Layer Interferometry were employed to assess binding.
- rPfbA49-684 binding was evaluated against intact RBCs and extracted surface glycolipids.
Main Results:
- Recombinant PfbA (rPfbA49-684) demonstrated broad carbohydrate specificity and significant affinity for human RBCs.
- PfbA exhibited a particular affinity for extracted RBC surface glycolipids.
- Moderate binding affinity was also observed between rPfbA49-684 and hemoglobin.
Conclusions:
- PfbA directly interacts with human red blood cells (RBCs).
- The affinity of PfbA for RBC surface glycolipids suggests a role in erythrocyte binding.
- This interaction is a potential mechanism contributing to S. pneumoniae's invasion of erythrocytes.
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