Infection by Streptococcus pneumoniae is a high prevalent in humans and responsible for a wide range of clinical manifestations such as pneumonia, meningitis, sepsis, and otitis media, causing significant morbidity and mortality worldwide, particularly among young children, the elderly, and immuno-compromised individuals.
Saponin adjuvants demonstrated greater potency in enhancing the immune response to two vaccines against Streptococcus. QS-21 significantly enhances IgG antibody titers with opsonophagocytic activity against multiple pneumococcal serotypes, including serotypes 3, 14, and 19A, which are commonly implicated in vaccine breakthrough infections [1]
Immunization with rSIP adjuvanted with ISCOM elicited a significant increase in IgA levels and a reduction in vaginal Group B Streptococcus (Soto et. al). A comparative study of Combo5 adjuvanted vaccines indicates a mayor survival rate for all saponin adjuvanted preparations compared to Alum, Inulin, CpG, Murabutide, Squalene (Figure 1) [2]. ISCOM and SMQ adjuvanted vaccine indicates a mixed Th1/Th2 immune response [2,3]. The superior protection conferred by saponin-based adjuvants may be attributed to the induction of a Th1 cellular response, in addition to the Th2 immune response, as hypothesized by Rivera-Hernandez [2]. Given that Streptococcus pneumoniae is a facultative intracellular bacterium, this balanced response may enhance protection by targeting both extracellular and intracellular phases of the pathogen’s lifecycle).
References
1. Kim, H. et al., 2022. Potentiating pneumococcal glycoconjugate vaccine PCV13 with saponin adjuvant VSA-1. Frontiers in Immunology, Volume 13.
2. Rivera-Hernandez, T. et al., 2020. Vaccine-Induced Th1-Type Response Protects against Invasive Group A Streptococcus Infection in the Absence of Opsonizing Antibodies. mBio, 11(2).
3. Soto, J. A. et al., 2019. Cellular immune response induced by surface immunogenic protein with AbISCO-100 adjuvant vaccination decreases group B Streptococcus vaginal colonization. Molecular Immunology, Volume 111, pp. 198-204.
