Synergistic immunostimulation between Leishmania donovani antigen and Carissa edulis in BALB/c mice with visceral leishmaniasis

Abstract Visceral leishmaniasis (VL) is a significant health issue because of limited administration of chemotherapy treatment, being too toxic and even emerging forms of resistance that necessitates to develop new forms of immunotherapeutic treatment. The research compared the adjuvant (vaccination) capacity of Carissa edulis extract combined with soluble Leishmania donovani antigen (SLA) in the BALB/c mice. Eighty BALB/c mice received SLA, C. edulis, combination, or PBS, then challenged with L. donovani; parasite, cytokine, antibodies measured. The highest protection in the mice vaccinated with SLA + C. edulis (4.9%-6.0) was observed, parasite burden which was lower as compared to the SLA + C. edulis (4.9) and also C. edulis (4.9). The biggest cytokine profile accused the best cytokines profile, with significantly higher levels of IFN-γ (217.4 pgmL (p = 0.0110)) as well as postponed levels of IL-10 (35-40 pgmL). The combination group showed robust activation of humoral response given that IgG2a performed as high as (3 mg/mL (p = 0.0245) markedly higher as compared to either treatment, whereas IgG1 increases were smaller and SLA-dependent. It was further ascertained that the level of parasite burden is positively correlated with IL-10 (r = 0.97, p = 0.0061) and IgG1 (r = 0.92, p = 0.0278), but negatively with IgG2a, which supports the protective nature of Th1-related immunities. The results have shown that the extract of C. edulis is synergistically antigenic stimulating the Th1-biased response with increased IFN-γ and IgG2a, and decreased IL-10, as well as enhanced the parasite clearance effect.