Update on the evolving landscape of pneumococcal capsule types: new discoveries and way forward

Feroze A Ganaie¹, Bernard W Beall², Jigui Yu¹, Mark van der Linden³, Lesley McGee⁴, Catherine Satzke^{5

6

7}, Sam Manna⁵, Stephanie W Lo^{8

9}, Stephen D Bentley⁸, Neil Ravenscroft¹⁰, Moon H Nahm¹

Affiliations

¹ Department of Medicine, Division of Pulmonary/Allergy/Critical Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA.
² Eagle Global Scientific, LLC, Contractor to Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
³ Reference Laboratory for Streptococci, Department of Medical Microbiology, University Hospital RWTH Aachen, Aachen, Germany.
⁴ Division of Bacterial Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
⁵ Infection, Immunity and Global Health, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.
⁶ Department of Pediatrics, The University of Melbourne, Melbourne, Victoria, Australia.
⁷ Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia.
⁸ Parasites and Microbes, Wellcome Sanger Institute, Cambridge, United Kingdom.
⁹ Milner Center for Evolution, Department of Life Sciences, University of Bath, Bath, United Kingdom.
¹⁰ Department of Chemistry, University of Cape Town, Rondebosch, South Africa.

PMID: 39878373
PMCID: PMC11905375 (available on 2026-01-29)
DOI: 10.1128/cmr.00175-24

Review

Update on the evolving landscape of pneumococcal capsule types: new discoveries and way forward

Feroze A Ganaie et al. Clin Microbiol Rev. 2025.

. 2025 Mar 13;38(1):e0017524.

doi: 10.1128/cmr.00175-24. Epub 2025 Jan 29.

Authors

Affiliations

¹ Department of Medicine, Division of Pulmonary/Allergy/Critical Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA.
² Eagle Global Scientific, LLC, Contractor to Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
³ Reference Laboratory for Streptococci, Department of Medical Microbiology, University Hospital RWTH Aachen, Aachen, Germany.
⁴ Division of Bacterial Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
⁵ Infection, Immunity and Global Health, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.
⁶ Department of Pediatrics, The University of Melbourne, Melbourne, Victoria, Australia.
⁷ Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia.
⁸ Parasites and Microbes, Wellcome Sanger Institute, Cambridge, United Kingdom.
⁹ Milner Center for Evolution, Department of Life Sciences, University of Bath, Bath, United Kingdom.
¹⁰ Department of Chemistry, University of Cape Town, Rondebosch, South Africa.

PMID: 39878373
PMCID: PMC11905375 (available on 2026-01-29)
DOI: 10.1128/cmr.00175-24

Abstract

SUMMARYStreptococcus pneumoniae (the "pneumococcus") is a significant human pathogen. The key determinant of pneumococcal fitness and virulence is its ability to produce a protective polysaccharide (PS) capsule, and anti-capsule antibodies mediate serotype-specific opsonophagocytic killing of bacteria. Notably, immunization with pneumococcal conjugate vaccines (PCVs) has effectively reduced the burden of disease caused by serotypes included in vaccines but has also spurred a relative upsurge in the prevalence of non-vaccine serotypes. Recent advancements in serotyping and bioinformatics surveillance tools coupled with high-resolution analytical techniques have enabled the discovery of numerous new capsule types, thereby providing a fresh perspective on the dynamic pneumococcal landscape. This review offers insights into the current pneumococcal seroepidemiology highlighting important serotype shifts in different global regions in the PCV era. It also comprehensively summarizes newly discovered serotypes from 2007 to 2024, alongside updates on revised chemical structures and the de-novo determinations of structures for previously known serotypes. Furthermore, we spotlight emerging evidence on non-pneumococcal Mitis-group strains that express capsular PS that are serologically and biochemically related to the pneumococcal capsule types. We further discuss the implications of these recent findings on capsule nomenclature, pneumococcal carriage detection, and future PCV design. The review maps out the current status and also outlines the course for future research and vaccine strategies, ensuring a continued effective response to the evolving pneumococcal challenge.

Keywords: Streptococcus pneumoniae; capsular overlap; capsular polysaccharide; capsule types; carbohydrate; pneumococcal conjugate vaccines; seroepidemiology; serotypes.

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Conflict of interest statement

UAB has intellectual property rights to several reagents developed in M.H.N.'s laboratory, and three of the authors (F.A.G., J.Y., and M.H.N.) are UAB employees. M.H.N. is a founder of SunFire Biotechnologies. C.S. is an investigator on a Pfizer collaborative research project on PCV impact and Principal Investigator of a Merck Investigator Studies Program grant on empyema funded by MSD, both outside this work. C.S. has participated in forums and seminars for Pfizer and MSD/Merck. The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the Centers for Disease Control and Prevention. The authors declare that they have no other relevant conflicts of interest.

References

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Update on the evolving landscape of pneumococcal capsule types: new discoveries and way forward

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Update on the evolving landscape of pneumococcal capsule types: new discoveries and way forward

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