Silva Herbert Guimarães de Sousa, Franzolin Marcia Regina, Anjos Geovana Ferreira Dos, Barbosa Angela Silva, Santos Luis Fernando Dos, Miranda Kaique Ferrari, Marques Ronaldo Maciel, Souza Matilde Costa Lima de, Piazza Roxane Maria Fontes, Domingos Marta de Oliveira
Laboratório de Bacteriologia, Instituto Butantan, Avenida Vital Brasil, 1500, São Paulo CEP 05503-900, SP, Brazil.
Centro de Bacteriologia, Núcleo de Doenças Entéricas, Instituto Adolfo Lutz, Avenida Dr. Arnaldo, 355, São Paulo CEP 01246-000, SP, Brazil.
Pathogens. 2022 Aug 9;11(8):895. doi: 10.3390/pathogens11080895.
The serogroup O55 of is composed of strains whose mechanisms of virulence are different from each other. Since the O55 polysaccharides are present in all O55 strains, and so are the polymers that compose the capsule of O55 atypical enteropathogenic (aEPEC), it was investigated whether anti-O55 antibodies were able to help the innate immune system to eliminate capsulated aEPEC and Shiga toxin-producing (STEC) belonging to the serogroup O55. The results demonstrate that the capsule of EPEC was able to inhibit the deposition of C3b on the bacterial surface and, as a consequence, their lysis by the alternative pathway of the complement system. However, in the presence of antibodies, the ability of the complement to lyse these pathogens was restored. It was also observed that macrophages were able to ingest EPEC and STEC, but they were only able to kill the ingested pathogens in the presence of antibodies. Anti-O55 antibodies were also able to inhibit aEPEC and STEC O55 adherence to human epithelial cells. In summary, the results demonstrated that the O55 polysaccharides have the potential to induce an effective humoral immune response against STEC and EPEC, indicating that they are good antigen targets to be used in vaccine formulations against these pathogens.
O55血清群由毒力机制彼此不同的菌株组成。由于O55多糖存在于所有O55菌株中，构成O55非典型肠致病性大肠杆菌（aEPEC）荚膜的聚合物也是如此，因此研究了抗O55抗体是否能够帮助先天免疫系统清除属于O55血清群的有荚膜aEPEC和产志贺毒素大肠杆菌（STEC）。结果表明，EPEC的荚膜能够抑制C3b在细菌表面的沉积，因此，补体系统的替代途径无法使其裂解。然而，在有抗体存在的情况下，补体裂解这些病原体的能力得以恢复。还观察到巨噬细胞能够摄取EPEC和STEC，但只有在有抗体存在时它们才能杀死摄取的病原体。抗O55抗体也能够抑制aEPEC和STEC O55对人上皮细胞的黏附。总之，结果表明O55多糖有潜力诱导针对STEC和EPEC的有效体液免疫反应，这表明它们是用于针对这些病原体的疫苗制剂的良好抗原靶点。
