RLJ-NE-299A: a new plant based vaccine adjuvant

Area of Science:

• Immunology
• Vaccinology
• Natural Product Chemistry

Background:

• Aluminum (alum) is a traditional vaccine adjuvant but has limitations in stimulating cell-mediated immunity.
• RLJ-NE-299A, a plant-derived product from Picrorhiza kurroa, exhibits immunostimulatory properties.
• There is a need for alternative adjuvants that can elicit robust and balanced immune responses.

Purpose of the Study:

• To evaluate RLJ-NE-299A as a potential alternative vaccine adjuvant.
• To compare the adjuvant activity of RLJ-NE-299A with alum using Hepatitis B surface antigen (HBsAg) in a mouse model.
• To assess the impact of RLJ-NE-299A on both cell-mediated and humoral immune responses.

Main Methods:

• Mice were immunized with HBsAg formulated with either RLJ-NE-299A or alum.
• Antigen-specific immune responses, including cytokine expression (Th1 and Th2) and immunoglobulin subtypes (IgG2a and IgG1), were measured.
• Cellular immune responses involving CD4 and CD8 T cells were analyzed.

Main Results:

• RLJ-NE-299A significantly upregulated Th1 (IL-2, IL-12, IFN-gamma, TNF-alpha) and Th2 (IL-4) cytokines.
• Both IgG2a (Th1) and IgG1 (Th2) antibody subtypes increased substantially in mice immunized with HBsAg/RLJ-NE-299A.
• RLJ-NE-299A induced T cell responses and overcame HBsAg non-responsiveness observed with alum-adjuvanted vaccines.

Conclusions:

• RLJ-NE-299A demonstrates strong potential as a vaccine adjuvant, enhancing both cell-mediated and humoral immunity.
• This plant-derived adjuvant is superior to alum in improving and sustaining immune status against HBsAg.
• RLJ-NE-299A may be a valuable adjuvant candidate for other vaccine antigens.