In silico Prediction of Pneumococcal truncated forms of DnaJ (hsp40) as Multivalent Pneumococcal Vaccine Antigens

Introduction and Objectives: Streptococcus pneumoniae colonizes the human nasopharynx and can cause diseases, including pneumonia, otitis media, septicemia and meningitis in pediatric, elderly, and immunocompromised populations. Presently, two types of pneumococcal polysaccharide-based vaccine are available. These vaccines have limitation of poor immunogenicity in children under two years old and limited serotype coverage. These limitations have provided the impetus for development of novel vaccines based on broadly representative, serotype-independent, highly-conserved pneumococcal protein antigens. DnaJ is a member of heat shock protein40 family (hsp40) and plays an important role in the pathogenesis of pneumococcal infection and is highly conserved in different serotypes of pneumococcal strains. Since after innate immune responses, humoral immune system has key defensive role in nasal and salivary mucosal sites against pneumococcal. Material and Methods: We used in-silico methods for predicting continuous antibody epitopes from DnaJ protein sequence. Using Immune Epitope Database(http://tools.iedb.org/bcell/), six prediction including bepipred linear epitope, Chou & Fasman Beta-Turn, Emini surface accessibility, Karplus & Schulz flexibility, Kolaskar & Tongaonkar antigenicity and Parker hydrophilicity were performed. Results: Our results were shown that according to the four first parameters including linear epitope, flexibility, surface accessibility and antigenicity predictions together and two another parameters (antigenicity and hydrophilicity), we could divide the DnaJ to two truncated forms. According to results of analysis of four first parameters, amino acids 1 to 139 at N-terminal of DnaJ had the highst scores and according to analysis of two parameters including antigenicity and hydrophilicity predictions, the truncated form of DnaJ (amino acids 140 to 378) can be prefer as proper truncated forms of DnaJ. Conclusion: Finally based on results, we can use truncated forms of DnaJ in stimulating immune system as immunogenic forms and in multivalent pneumococcal vaccines design. In future we will design fusion truncated forms of DnaJ with other pneumococcal proteins and will investigate in-vivo immunogenicity of these truncated forms.

Keywords:

Hsp40 , Streptococcus pneumoniae , Multivalent Pneumococcal Vaccine , Bioinformatics , Iran.