Shalash Ahmed O, Sun Haolan, Cui Yiru, Wang Jingwen, Arnts Barb, Bauer Jannah, Hussein Waleed M, Khalil Zeinab G, Skwarczynski Mariusz, Toth Istvan
School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia.
Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Biological Resources, Brisbane, QLD 4072, Australia.
Vaccines (Basel). 2025 Jun 12;13(6):632. doi: 10.3390/vaccines13060632.
(GAS) is a major human pathogen associated with serious diseases. Evaluating immune responses against GAS vaccines-immunogenicity, quality, and efficacy-is complicated by interference from co-infections, like (). We aimed to evaluate peptide-based GAS vaccines in mice for antisera efficacy against standard and mutant GAS strains and to assess immunological methods under co-infection conditions.
Female C57BL/6 mice were infected with and immunized with various M-protein-derived peptide antigens: J8, J8i, J8i-J8i, and the native p145 sequence. Two novel, conserved M-protein-derived antigens (NTD and CTD2) were also evaluated. Enzyme-linked immunosorbent assays (ELISAs) were used to assess immunogenicity and GAS-specific antibody responses. Peptide antigens were either conjugated to or physically mixed with the PADRE T-helper epitope and tested for enhanced antisera immunogenicity and opsonic efficacy.
ELISA against the immunizing peptides as coating antigens reflected the immunogenicity, while p145-based ELISA correlated with GAS-specific antibody titres without interference for J8-based vaccines. Immunogenicity ranked J8 > J8i ≈ J8i-J8i > p145. NTD and CTD2 antisera demonstrated opsonic activity, indicating protective potential. PADRE-J8 conjugates significantly enhanced antibody magnitude and quality, producing strong opsonic bactericidal responses against both standard and p145-mutant GAS strains. PADRE-J8i was effective only against standard strains. This is the first report to suggest at least two B-cell epitopes within the J8i peptide.
These findings support the diagnostic utility of p145, NTD, and CTD2 under co-infection settings, and the vaccine potential of J8, NTD, and CTD2, particularly when conjugated to a T helper for enhanced antigen presentation.
A群链球菌（GAS）是一种与严重疾病相关的主要人类病原体。评估针对GAS疫苗的免疫反应——免疫原性、质量和效力——会因合并感染（如……）的干扰而变得复杂。我们旨在评估基于肽的GAS疫苗在小鼠中针对标准和突变GAS菌株的抗血清效力，并评估合并感染条件下的免疫学方法。
雌性C57BL/6小鼠感染……并用各种M蛋白衍生肽抗原进行免疫：J8、J8i、J8i-J8i和天然p145序列。还评估了两种新的、保守的M蛋白衍生抗原（NTD和CTD2）。采用酶联免疫吸附测定（ELISA）评估免疫原性和GAS特异性抗体反应。肽抗原与PADRE T辅助表位偶联或物理混合，并测试其增强抗血清免疫原性和调理效力。
以免疫肽作为包被抗原的ELISA反映了免疫原性，而基于p145的ELISA与GAS特异性抗体滴度相关，对基于J8的疫苗无干扰。免疫原性排序为J8 > J8i ≈ J8i-J8i > p145。NTD和CTD2抗血清表现出调理活性，表明具有保护潜力。PADRE-J8偶联物显著提高了抗体量和质量，对标准和p145突变GAS菌株均产生强烈的调理杀菌反应。PADRE-J8i仅对标准菌株有效。这是首次报告提示J8i肽内至少有两个B细胞表位。
这些发现支持p145、NTD和CTD2在合并感染情况下的诊断效用，以及J8、NTD和CTD2的疫苗潜力，特别是当与T辅助物偶联以增强抗原呈递时。
