Pathogenicity of invasive and non-invasive CC4821 Neisseria meningitidis

Neisseria meningitidis (N. meningitidis) is an opportunistic pathogen that typically colonizes the mucosal surfaces of the nasopharynx. Under certain conditions, N. meningitidis can lead to invasive meningococcal disease (IMD). Nevertheless, whether invasive and non-invasive isolates of N. meningitidis exhibit distinct virulence characteristics remains unresolved. In this study, we investigated the differences in pathogenicity between non-invasive and invasive isolates with highly similar genomic information from an outbreak belonging to CC4821. The isolates were assessed for adhesion and invasion, evaluated for proinflammatory responses, and analyzed for their capacity to induce apoptosis. Our findings demonstrated that non-invasive isolates exhibit significantly greater adhesion to epithelial and endothelial cells than invasive isolates do. Both invasive and non-invasive isolates elicited robust proinflammatory responses. However, the serogroup C and non-groupable isolates induced varying magnitudes of proinflammatory responses in epithelial and endothelial cells while exerting comparable effects on macrophages. Notably, the non-invasive isolate QH07 exhibited significantly greater invasive potential against both endothelial and epithelial cells than the other non-invasive and invasive isolates. Furthermore, this particular non-invasive isolate exhibited a robust ability to induce apoptosis. These results indicate that highly pathogenic strains may be present within non-invasive isolates, emphasizing the necessity of enhancing the surveillance of carriers within the healthy population.