IMPACT OF VARIATIONS IN THE POLYSACCHARIDE CAPSULE ON THE VIRULENCE OF PNEUMOCOCCUS IN VITRO

• Grant number: 24/22743-0
• Support Opportunities: Scholarships in Brazil - Master
• Start date: September 01, 2025
• End date: February 28, 2027
• Field of knowledge: Biological Sciences - Microbiology - Biology and Physiology of Microorganisms
• Principal Investigator: Thiago Rojas Converso
• Grantee: Giulia Vicente Destro
• Host Institution: Universidade São Francisco (USF). Campus Bragança Paulista. Bragança Paulista , SP, Brazil

Abstract

Streptococcus pneumoniae is a Gram-positive bacterium, a natural resident of the human nasopharynx, that plays a crucial role in the pathogenesis of both invasive and non-invasive diseases such as pneumonia, meningitis, otitis media, and sepsis. One of the most significant virulence factors of this species is its polysaccharide capsule (CPS), an essential structure that protects the bacterium from phagocytosis and facilitates its persistence in the host. There are over 100 serotypes of S. pneumoniae, varying according to the composition and structural organization of the CPS, reflecting differences in the pathogenicity and immunogenicity of each serotype. Therefore, this study aims to investigate the impact of the capsular polysaccharide on the ability of S. pneumoniae to form biofilms, establish colonization, impact quorum sensing, and regulate virulence genes: luxS, comD, ply, pavB, and cbpD. For this purpose, isogenic strains derived from TIGR4, carrying different variants of polysaccharide capsules, will be used, and the biofilm formation on abiotic and biotic surfaces will be evaluated, as well as bacterial communication mediated by quorum sensing and the expression of virulence genes. Additionally, bacterial adhesion and invasion in NCI-H292. Thus, it will be possible to understand how the polysaccharide capsule is involved in the pathogenicity and virulence factors of S. pneumoniae. (AU)