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Immunisation With Immunodominant Linear B Cell Epitopes Vaccine of Manganese Transport Protein C Confers Protection against Staphylococcus aureus Infection.

Yang HJ, Zhang JY, Wei C, Yang LY, Zuo QF, Zhuang Y, Feng YJ, Srinivas S, Zeng H, Zou QM - PLoS ONE (2016)

Bottom Line: On the basis of the results, linear B cell epitopes within MntC were finely mapped using a series of overlapping synthetic peptides.Further studies indicate that MntC113-136, MntC209-232, and MntC263-286 might be the original linear B-cell immune dominant epitope of MntC, furthermore, three-dimensional (3-d) crystal structure results indicate that the three immunodominant epitopes were displayed on the surface of the MntC antigen.On the basis of immunodominant MntC113-136, MntC209-232, and MntC263-286 peptides, the epitope vaccine for S. aureus induces a high antibody level which is biased to TH2 and provides effective immune protection and strong opsonophagocytic killing activity in vitro against MRSA infection.

View Article: PubMed Central - PubMed

Affiliation: National Engineering Research Centre for Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing 400038, PR China.

ABSTRACT
Vaccination strategies for Staphylococcus aureus, particularly methicillin-resistant S. aureus (MRSA) infections have attracted much research attention. Recent efforts have been made to select manganese transport protein C, or manganese binding surface lipoprotein C (MntC), which is a metal ion associated with pathogen nutrition uptake, as potential candidates for an S. aureus vaccine. Although protective humoral immune responses to MntC are well-characterised, much less is known about detailed MntC-specific B cell epitope mapping and particularly epitope vaccines, which are less-time consuming and more convenient. In this study, we generated a recombinant protein rMntC which induced strong antibody response when used for immunisation with CFA/IFA adjuvant. On the basis of the results, linear B cell epitopes within MntC were finely mapped using a series of overlapping synthetic peptides. Further studies indicate that MntC113-136, MntC209-232, and MntC263-286 might be the original linear B-cell immune dominant epitope of MntC, furthermore, three-dimensional (3-d) crystal structure results indicate that the three immunodominant epitopes were displayed on the surface of the MntC antigen. On the basis of immunodominant MntC113-136, MntC209-232, and MntC263-286 peptides, the epitope vaccine for S. aureus induces a high antibody level which is biased to TH2 and provides effective immune protection and strong opsonophagocytic killing activity in vitro against MRSA infection. In summary, the study provides strong proof of the optimisation of MRSA B cell epitope vaccine designs and their use, which was based on the MntC antigen in the development of an MRSA vaccine.

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OPKA of antisera to peptides (Anti-peptides) or rMntC (anti-rMntC) against MRSA252.2 × 106 CFU S. aureus strains were incubated in the presence of 2 × 106 HL60 cells and mouse antisera against rMntC and peptide vaccine in the presence of infant rabbit complement. A percentage of MRSA252 was killed in the opsonophagocytic assay. Bars represent percentage killing compared with NMS represented as a mean of quadruplicate samples with SEM. NMS: no mouse antisera. No complement: no infant rabbit complement.
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pone.0149638.g006: OPKA of antisera to peptides (Anti-peptides) or rMntC (anti-rMntC) against MRSA252.2 × 106 CFU S. aureus strains were incubated in the presence of 2 × 106 HL60 cells and mouse antisera against rMntC and peptide vaccine in the presence of infant rabbit complement. A percentage of MRSA252 was killed in the opsonophagocytic assay. Bars represent percentage killing compared with NMS represented as a mean of quadruplicate samples with SEM. NMS: no mouse antisera. No complement: no infant rabbit complement.

Mentions: Although immunisation with polypeptides can induce a strong humoral immune response in vivo, whether these peptide-specific antibodies provided protective immunity in vitro remained unclear. To evaluate the efficacy of the peptide-specific antibody, an opsonophagocytic killing assay (OPKA), which measured antibody and complement-mediated bacterial killing, was performed in vitro. The killing assay was conducted by using mouse antiserum of specimens immunised with peptide, and rMntC, vaccinations and neutrophil-like cells HL60, which play an important role in host clearance of S. aureus. In the presence of HL60 phagocytic cells and infant rabbit serum complement, mouse IgG raised by various vaccines exhibited different opsonophagocytic killing activities for S. aureus MRSA252 strains. As shown in Fig 6, the percentages of S. aureus killed by the peptide-MntC113-136, peptide-MntC209-232, and peptide-MntC263-286 specific antibody were smaller than the desired percentage (usually 50%) [23], which was only slightly significant. However, opsonophagocytic killing activities of rMntC-specific and polypeptide-specific antibody were 86.9% and 89.5%, respectively: these were still significant even when using 1:3 diluted antibody serums (i.e. greater than 50%) (Results are not shown). The polyclonal antibodies of polypeptide vaccine were effective in preventing bacteraemia, and were superior to other vaccine groups’ trialled in this study. This indicated that the protective effect of the polypeptide vaccination was mostly antibody-mediated. Opsonophagocytic properties of antibodies were assayed in vitro, and showed that specific-polypeptide antibodies behaved more effectively in phagocytosis of the bacteria. These results confirmed that polypeptide-specific antibody was able to kill S. aureus cells efficiently in vitro and may be responsible for the prevention of full-blown infection and bacterial persistence.


Immunisation With Immunodominant Linear B Cell Epitopes Vaccine of Manganese Transport Protein C Confers Protection against Staphylococcus aureus Infection.

Yang HJ, Zhang JY, Wei C, Yang LY, Zuo QF, Zhuang Y, Feng YJ, Srinivas S, Zeng H, Zou QM - PLoS ONE (2016)

OPKA of antisera to peptides (Anti-peptides) or rMntC (anti-rMntC) against MRSA252.2 × 106 CFU S. aureus strains were incubated in the presence of 2 × 106 HL60 cells and mouse antisera against rMntC and peptide vaccine in the presence of infant rabbit complement. A percentage of MRSA252 was killed in the opsonophagocytic assay. Bars represent percentage killing compared with NMS represented as a mean of quadruplicate samples with SEM. NMS: no mouse antisera. No complement: no infant rabbit complement.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4764517&req=5

pone.0149638.g006: OPKA of antisera to peptides (Anti-peptides) or rMntC (anti-rMntC) against MRSA252.2 × 106 CFU S. aureus strains were incubated in the presence of 2 × 106 HL60 cells and mouse antisera against rMntC and peptide vaccine in the presence of infant rabbit complement. A percentage of MRSA252 was killed in the opsonophagocytic assay. Bars represent percentage killing compared with NMS represented as a mean of quadruplicate samples with SEM. NMS: no mouse antisera. No complement: no infant rabbit complement.
Mentions: Although immunisation with polypeptides can induce a strong humoral immune response in vivo, whether these peptide-specific antibodies provided protective immunity in vitro remained unclear. To evaluate the efficacy of the peptide-specific antibody, an opsonophagocytic killing assay (OPKA), which measured antibody and complement-mediated bacterial killing, was performed in vitro. The killing assay was conducted by using mouse antiserum of specimens immunised with peptide, and rMntC, vaccinations and neutrophil-like cells HL60, which play an important role in host clearance of S. aureus. In the presence of HL60 phagocytic cells and infant rabbit serum complement, mouse IgG raised by various vaccines exhibited different opsonophagocytic killing activities for S. aureus MRSA252 strains. As shown in Fig 6, the percentages of S. aureus killed by the peptide-MntC113-136, peptide-MntC209-232, and peptide-MntC263-286 specific antibody were smaller than the desired percentage (usually 50%) [23], which was only slightly significant. However, opsonophagocytic killing activities of rMntC-specific and polypeptide-specific antibody were 86.9% and 89.5%, respectively: these were still significant even when using 1:3 diluted antibody serums (i.e. greater than 50%) (Results are not shown). The polyclonal antibodies of polypeptide vaccine were effective in preventing bacteraemia, and were superior to other vaccine groups’ trialled in this study. This indicated that the protective effect of the polypeptide vaccination was mostly antibody-mediated. Opsonophagocytic properties of antibodies were assayed in vitro, and showed that specific-polypeptide antibodies behaved more effectively in phagocytosis of the bacteria. These results confirmed that polypeptide-specific antibody was able to kill S. aureus cells efficiently in vitro and may be responsible for the prevention of full-blown infection and bacterial persistence.

Bottom Line: On the basis of the results, linear B cell epitopes within MntC were finely mapped using a series of overlapping synthetic peptides.Further studies indicate that MntC113-136, MntC209-232, and MntC263-286 might be the original linear B-cell immune dominant epitope of MntC, furthermore, three-dimensional (3-d) crystal structure results indicate that the three immunodominant epitopes were displayed on the surface of the MntC antigen.On the basis of immunodominant MntC113-136, MntC209-232, and MntC263-286 peptides, the epitope vaccine for S. aureus induces a high antibody level which is biased to TH2 and provides effective immune protection and strong opsonophagocytic killing activity in vitro against MRSA infection.

View Article: PubMed Central - PubMed

Affiliation: National Engineering Research Centre for Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing 400038, PR China.

ABSTRACT
Vaccination strategies for Staphylococcus aureus, particularly methicillin-resistant S. aureus (MRSA) infections have attracted much research attention. Recent efforts have been made to select manganese transport protein C, or manganese binding surface lipoprotein C (MntC), which is a metal ion associated with pathogen nutrition uptake, as potential candidates for an S. aureus vaccine. Although protective humoral immune responses to MntC are well-characterised, much less is known about detailed MntC-specific B cell epitope mapping and particularly epitope vaccines, which are less-time consuming and more convenient. In this study, we generated a recombinant protein rMntC which induced strong antibody response when used for immunisation with CFA/IFA adjuvant. On the basis of the results, linear B cell epitopes within MntC were finely mapped using a series of overlapping synthetic peptides. Further studies indicate that MntC113-136, MntC209-232, and MntC263-286 might be the original linear B-cell immune dominant epitope of MntC, furthermore, three-dimensional (3-d) crystal structure results indicate that the three immunodominant epitopes were displayed on the surface of the MntC antigen. On the basis of immunodominant MntC113-136, MntC209-232, and MntC263-286 peptides, the epitope vaccine for S. aureus induces a high antibody level which is biased to TH2 and provides effective immune protection and strong opsonophagocytic killing activity in vitro against MRSA infection. In summary, the study provides strong proof of the optimisation of MRSA B cell epitope vaccine designs and their use, which was based on the MntC antigen in the development of an MRSA vaccine.

Show MeSH
Related in: MedlinePlus