Background
Streptococcus pneumoniae
, more than 90 serotypes of which exist, is recognized as an etiologic agent of pneumonia, meningitis, and sepsis associated with significant morbidity and mortality worldwide. Immunization with a pneumococcal
pep27
mutant (Δ
pep27
) has been shown to confer comprehensive, long-term protection against even nontypeable strains. However, Δ
pep27
is effective as a vaccine only after at least three rounds of immunization. Therefore, treatments capable of enhancing the efficiency of Δ
pep27
immunization should be identified without delay.
Panax ginseng
Mayer has already been shown to have pharmacological and antioxidant effects. Here, the ability of Korean Red Ginseng (KRG) to enhance the efficacy of Δ
pep27
immunization was investigated.
Methods
Mice were treated with KRG and immunized with Δ
pep27
before infection with the pathogenic
S. pneumoniae
strain D39. Total reactive oxygen species production was measured using lung homogenates, and inducible nitric oxide (NO) synthase and antiapoptotic protein expression was determined by immunoblotting. The phagocytic activity of peritoneal macrophages was also tested after KRG treatment.
Results
Compared with the other treatments, KRG significantly increased survival rate after lethal challenge and resulted in faster bacterial clearance via increased phagocytosis. Moreover, KRG enhanced Δ
pep27
vaccine efficacy by inhibiting reactive oxygen species production, reducing extracellular signal–regulated kinase apoptosis signaling and inflammation.
Conclusion
Taken together, our results suggest that KRG reduces the time required for immunization with the Δ
pep27
vaccine by enhancing its efficacy.