title: Immunogenicity and protective efficacy of DnaJ (hsp40) of Streptococcus pneumoniae against lethal infection in mice.
abstract: The present study was carried out to evaluate the immunogenicity and protective efficacy of DnaJ (hsp40) of Streptococcus pneumoniae, by cloning the full-length DnaJ of S. pneumoniae and expressing in heterologous host E. coli BL-21 (DE3). PCR amplified DnaJ was ligated in pQE-30 expression vector and subsequently transformed in E. coli DH5alpha strain. Cloning of DnaJ was confirmed by double digestion and PCR, followed by DNA sequencing. The His-tag containing recombinant protein was purified by Ni-NTA affinity chromatography. To determine the immunogenicity of DnaJ, the mice (10 mice/group) were immunized by injecting 40 microg DnaJ protein/mouse i.p. There was a significant increase in IgG titres (2 x 10(5)) in mice immunized with DnaJ protein. Isotyping studies revealed that antibodies produced are predominantly IgG2a type indicating the predominance of Th1 response. A significant increase in lymphocyte proliferation was observed in mice immunized with DnaJ protein as compared to the control mice. Further, there was a significant increase in IL-2 and gamma-IFN levels in culture supernatants of splenocytes isolated from immunized mice. To determine the efficacy of DnaJ vaccination in eliciting protection, the mice were challenged with 1 x 10(5)cells of S. pneumoniae A66 type 3 capsular strain intra-nasally after 7 days of last immunization. All the control mice died within 2 days of post-infection, while 70% of animals immunized with DnaJ survived the lethal challenge by S. pneumoniae. The study reveals that immunization of mice with DnaJ elicits protective immunity against S. pneumoniae infection.
authors.affiliation: Department of Experimental Biology, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi 110054, India.
authors.forename: Mohd Nadeem
authors.initials: MN
authors.lastname: Khan
authors.forename: Anju
authors.initials: A
authors.lastname: Bansal
authors.forename: Dhananjay
authors.initials: D
authors.lastname: Shukla
authors.forename: Piyush
authors.initials: P
authors.lastname: Paliwal
authors.forename: S K S
authors.initials: SK
authors.lastname: Sarada
authors.forename: Sai Ram
authors.initials: SR
authors.lastname: Mustoori
authors.forename: Pratul Kumar
authors.initials: PK
authors.lastname: Banerjee
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000276:immunology; D005260:Female; D050956:HSP40 Heat-Shock Proteins / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D007074:Immunoglobulin G / Q000276:immunology; D007371:Interferon-gamma / Q000276:immunology; D007376:Interleukin-2 / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D011008:Pneumococcal Infections / Q000276:immunology / Q000517:prevention & control*; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology
chemical_list: D050956:HSP40 Heat-Shock Proteins; D007074:Immunoglobulin G; D007376:Interleukin-2; D011994:Recombinant Proteins; D007371:Interferon-gamma