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Inmunidad cruzada dentro de los serogrupos de neumococos: Implicaciones para el desarrollo de vacunas de próxima

A-Yeung Jang¹, Hyun Jung Ji², Eun Hye Kang³

¹Division of Infectious Disease, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea; Vaccine Innovation Center-KU Medicine (VIC-K), Seoul, Republic of Korea.

|December 31, 2025

Abstracto

Objectives:

This study aims to investigate within-serogroup cross-reactive immunity among pneumococcal serotypes using inhibition opsonophagocytic assays (OPA). The findings provide immunologic insights into serotype-replacement dynamics with implications for the design of future pneumococcal vaccines.

Methods:

Pooled sera were prepared from 24 adults aged ≥40 years: Pool 1 (PCV13/PPSV23 recipients), Pool 2 (PCV20 recipients), and Pool 3 (PCV21 recipients). Cross-reactivity was examined across five major serogroups (6, 9, 15, 19, 23) by measuring residual OPA titers after adsorption with homologous or heterologous inactivated pneumococcal strain.

Results:

Cross-reactivity varied by serogroup. In serogroup 6, 6A induced broad cross-protection against 6B and 6C, whereas 6D showed only homologous reactivity. In serogroup 15, inhibition OPA revealed inconsistent cross-reactivity between serotypes 15B and 15C, with only limited cross-reactivity observed for 15A. Pooled sera from PCV21 recipients (containing 15A and 15C) demonstrated pronounced heterologous inhibition toward 15B. In serogroup 19, cross-reactivity between 19A and 19F was partial and asymmetric. Heterologous adsorption showed negligible reductions in OPA titers for serogroups 9 and 23.

Conclusions:

The inhibition OPA enabled a precise assessment of serogroup-level cross-reactive immunity, revealing heterogeneous patterns of cross-reactivity. These findings underscore the need for careful serotype selection and epitope evaluation in next-generation vaccine formulations.

Palabras clave:

Inmunogenicidad cruzada Vacuna antineumocócica Neumococo Serogrupo Reemplazo de serotipos

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