Psp140: an immunodominant antigen in the supernatant of Streptococcus pneumoniae culture

  • Davoud Afshar Department of Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
  • Solmaz Ohadian Moghadam Uro-Oncology Research Center, Tehran University of Medical Sciences, Tehran, Iran
  • Farhad Safarpoor Dehkordi Halal Research Center of IRI, FDA, Tehran, Iran
  • Reza Ranjbar Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
  • Amir Hasanzadeh Department of Microbiology, Maragheh University of Medical Sciences, Maragheh, Iran
Enzyme-linked immunosorbent assay;, Immunodominant antigen;, Streptococcus pneumoniae;, Western blot


Background and Objectives: Streptococcus pneumoniae causes many lethal infections. Due to its reduced sensitivity to commonly used antibiotics, development of new strategies against pneumococcal infections seems to be necessary. We aimed to investigate immunodominant antigens in S. pneumoniae culture supernatant in order to develop novel targets for pneumococcal vaccines.
Materials and Methods: In this study S. pneumoniae ATCC49619 was sub-cultured into BHI broth from overnight culture at 37°C for 4 h. The supernatant proteins were precipitated using acetone precipitation method. A rabbit was intramuscularly immunized with alum adjuvant and 100 μg pneumococcal supernatant proteins, 6 times at 14 days' intervals to produce hyperimmune serum. ELISA assay was performed to determine the antibody level response to pneumococcal secretory proteins. Then dot blot applied for rapid evaluation of hyperimmune serum reactivity to pneumococcus supernatant proteins. The western blot was also used to determine the interaction of supernatant proteins with immunogenic rabbit's hyperimmune-serum.
Results: According to the western blot analysis, the immunodominant protein had 140KDa molecular weight and designated as pneumococcal secretory protein140 (Psp140).
Conclusion: The Psp140 protein in the supernatant of S. pneumoniae culture is an immunodominant protein and it is likely related to pneumococcal secretory protein or surface exposed protein which released into culture supernatant during bacterial growth.


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How to Cite
Afshar D, Ohadian Moghadam S, Safarpoor Dehkordi F, Ranjbar R, Hasanzadeh A. Psp140: an immunodominant antigen in the supernatant of Streptococcus pneumoniae culture. Iran J Microbiol. 12(4):338-342.
Original Article(s)