title: Enhanced protection against pneumococcal infection elicited by immunization with the combination of PspA, PspC, and ClpP.
abstract: Immunization with a combination of several virulence-associated proteins is one of the strategies of developing effective protein-based vaccines to enhance the protection against Streptococcus pneumoniae. In this study, we evaluated the protection effects against pneumococcal infection caused by S. pneumoniae TIGR4 in BALB/c mice immunized with either single pneumococcal surface protein A (PspA), pneumococcal surface protein C (PspC), the caseinolytic protease (ClpP) or their combinations. The median survival times for mice immunized with single antigen or their combinations were significantly longer than that for mice treated with adjuvant alone. Mice treated with a combination of three antigens survived significantly longer than those that received either single or two antigens. The highest survival rate of the various groups of mice was observed with the combination of three antigens, this survival rate was significantly different from those for mice that received either single antigen or the combinations of two antigens except the mixture of ClpP and PspA. In the experiment of passive immunization with hyperimmune serums containing their specific polyclonal antibodies (anti-PspA serum, anti-PspC serum, anti-ClpP serum), the median survival times for mice immunized with hyperimmune serums containing specific polyclonal antibodies were significantly longer than that for control mice, the treatment of serum containing only one single polyclonal antibody could not provide higher survival rate than control serum. However, the survival rates for mice treated with the serums containing combined polyclonal antibodies were significantly higher than those for mice treated with either control serum or anti-PspA serum alone. Immunization with the combination of three hyperimmune serums also provided the best protection against S. pneumoniae. Compared to mice treated with serum containing single polyclonal antibody, the survival rate for mice treated with serums containing three polyclonal antibodies was significantly higher but was not different from those for mice treated with serums containing two polyclonal antibodies. Our findings provided evidence that a mixture of PspA, PspC, and ClpP or their polyclonal antibodies could enhance the protection against pneumococcal infection acting a synergetic effect.
authors.affiliation: Key Laboratory of Laboratory Medical Diagnostics of Ministry of Education, Department of Laboratory Medicine in Chongqing Medical University, Chongqing 400016, PR China.
authors.forename: Ju
authors.initials: J
authors.lastname: Cao
authors.forename: Dapeng
authors.initials: D
authors.lastname: Chen
authors.forename: Wenchun
authors.initials: W
authors.lastname: Xu
authors.forename: Tingmei
authors.initials: T
authors.lastname: Chen
authors.forename: Songxiao
authors.initials: S
authors.lastname: Xu
authors.forename: Jingyong
authors.initials: J
authors.lastname: Luo
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
authors.forename: Beizhong
authors.initials: B
authors.lastname: Liu
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Wang
authors.forename: Xuemei
authors.initials: X
authors.lastname: Zhang
authors.forename: Youlan
authors.initials: Y
authors.lastname: Shan
authors.forename: Yibing
authors.initials: Y
authors.lastname: Yin
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000276:immunology*; D015153:Blotting, Western; D049071:Endopeptidase Clp; D004797:Enzyme-Linked Immunosorbent Assay; D007114:Immunization; D007116:Immunization, Passive; D051379:Mice; D008807:Mice, Inbred BALB C; D011008:Pneumococcal Infections / Q000382:microbiology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000627:therapeutic use*; D011994:Recombinant Proteins / Q000276:immunology; D012697:Serine Endopeptidases / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000276:immunology; D016019:Survival Analysis; D018074:Vaccines, Conjugate / Q000627:therapeutic use
chemical_list: D001426:Bacterial Proteins; D022242:Pneumococcal Vaccines; D011994:Recombinant Proteins; D018074:Vaccines, Conjugate; C051592:pneumococcal surface protein A; D012697:Serine Endopeptidases; C501427:ClpP protein, Streptococcus pneumoniae; D049071:Endopeptidase Clp