Novel Immunoprotective Proteins of Streptococcus pneumoniae Identified by Opsonophagocytosis Killing Screen.

Abstract

The success of polysaccharide conjugate vaccines represents a major advance in the prevention of pneumococcal disease, but the power of these vaccines is limited by partial spectrum of coverage and high cost. Vaccines using immunoprotective proteins are a promising alternative type of pneumococcal vaccines. In this study, we constructed a library of antisera against conserved pneumococcal proteins predicted to be associated with cell surface or virulence using a combination of bioinformatic prediction and immunization of rabbits with recombinant proteins. Screening of the library by an opsonophagocytosis killing (OPK) assay identified the OPK-positive antisera, which represented 15 (OPK-positive) proteins. Further tests showed that virtually all of these OPK-positive antisera conferred passive protection against lethal infection of virulent pneumococci. More importantly, immunization with recombinant forms of three OPK-positive proteins (SP148, PBP2b, and ScpB), alone or in combination, conferred significant protection against lethal challenge of pneumococcal strains representing capsular serotypes 3, 4, and 6A in a mouse sepsis model. To our best knowledge, this work represents the first example in which novel vaccine candidates are successfully identified by the OPK screening. Our data have also provided further confirmation that the OPK activity may serve as a reliable in vitro surrogate for evaluating vaccine efficacy of pneumococcal proteins.

• Authors: Yang Wang, Zhensong Wen, Xiaolei Pan, David E Briles, Yongqun He, Jing-Ren Zhang
• Journal: Infection and immunity (Infect Immun) Vol. 86 Issue 9 (09 2018) ISSN: 1098-5522 [Electronic] United States
• PMID: 29891544 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2018 American Society for Microbiology.

Chemical References

• Antibodies, Bacterial
• Bacterial Proteins
• Opsonin Proteins
• Pneumococcal Vaccines
• Recombinant Proteins

Topics

• Animals
• Antibodies, Bacterial (immunology)
• Bacterial Proteins (immunology)
• Computational Biology
• Disease Models, Animal
• Female
• High-Throughput Screening Assays
• Immunization
• Immunization, Passive
• Mice
• Mice, Inbred BALB C
• Opsonin Proteins (immunology)
• Phagocytosis
• Pneumococcal Infections (immunology, prevention & control)
• Pneumococcal Vaccines (immunology)
• Rabbits
• Recombinant Proteins (administration & dosage, immunology)
• Streptococcus pneumoniae (immunology, pathogenicity)