Recombinant Production and Innovative Purification of Pneumolysin Protein: A Promising Multi-Functional Pneumococcal Virulence Factor for Next-Generation Pneumococcal Vaccines and Alternative Treatments

Streptococcus pneumoniae is an opportunistic pathogen responsible for widespread infectious diseases and remains a significant global public health concern, particularly for children, individuals over the age of 65, and immunocompromised populations. As the primary causative agent for the majority of bacterial pneumonias, S. pneumoniae can also lead to systemic infections such as otitis media (middle ear infection), meningitis (inflammation of the brain and spinal cord membranes), and sepsis (bloodstream infection). The Pneumolysin (PLY) protein, secreted by the S. pneumoniae pathogen and acting as a "pore-forming toxin" during infection, is a cholesterol-dependent cytolysin (CDC). It is a fundamental pneumococcal virulence factor, playing a critical role in all stages of pneumococcal disease, including transmission, colonization, and infection. Also known as a hemolysin, Pneumolysin causes the disintegration of erythrocyte cell membranes and contributes to inflammation and bacterial penetration by directly damaging cells through pore-forming cytolytic activity. Furthermore, PLY facilitates bacterial evasion by blocking complement activation within the immune system and serves as a key factor in host-to-host transmission.

Recombinantly produced pneumolysin is currently utilized as a protein carrier (adjuvant) for pneumococcal type 18C conjugate vaccines. Furthermore, numerous studies indicate that PLY toxoids and their detoxified forms hold significant potential as vaccine candidates in protein-based vaccines and for therapeutic applications. Consequently, the high-yield and high-purity acquisition of pneumolysin through recombinant methods—as a modern alternative to conventional production techniques in literature—carries critical value for its utilization in diagnostic kits, alternative treatments, and vaccine manufacturing.

Within the scope of Türkiye Vaccine Institute’s mission to enable R&D activities through the transfer of technical expertise (know-how), it is envisioned that the production of pneumolysin for these specific purposes will constitute a vital milestone. This initiative aligns with the strategic goal of developing vaccines and their essential components (such as adjuvants) by leveraging the techniques and methodologies developed or produced through such expertise.

In this regard, the project aims to develop a product with high added value and export potential by establishing an R&D infrastructure for its use in diagnostic kits, alternative treatments, and vaccine production stages. This will be achieved through the high-yield and high-purity acquisition of recombinant Pneumolysin, utilizing an innovative, molecular imprinting-based purification column—the first of its kind to be produced globally.

The project is being conducted by the R&D specialists and research personnel of Türkiye Vaccine Institute.