BALB/c mice vaccinated with soluble Leishmania major antigens plus pristane adjuvant develop Th 1 immune response...

Leishmaniasis is a major global public health concern but current control measures are unreliable. Vaccination is likely the best control method, but despite efforts to develop a vaccine, none has been approved for human use. This study evaluated the antileishmanial potential of a vaccine combining 2,6,10,14-tetramethylpentadecane (pristane) as an adjuvant plus soluble Leishmania major antigens (SLmAgs) in BALB/c mice.

Mice were randomly assigned to four groups and treated as: group 1 - SLmAgs + pristane; group 2 - SLmAgs alone; group 3 - BCG + SLmAg (positive control) and group 4 - phosphate buffered saline (negative control). At 31 days post-vaccination, immune response was assessed by measuring the production of interleukin-10 (IL-10); interferon-gamma (IFN-γ) and CD4+/CD8+ T cells using flow cytometry. Protection against cutaneous leishmaniasis was determined after infecting the mice with virulent L. major promastigotes (at 31 days post-vaccination) and measuring the footpad lesion size and determining parasite loads in infected footpads using the limiting dilution assay at 45 days post infection.

Following vaccination with SLmAgs + pristane as an adjuvant, the mice produced higher amounts of Th 1 cytokine- IFN-γ compared to Th2 cytokine IL-10 and a significantly higher amount of CD4+ compared to CD8+ T cells, with corresponding smaller lesion sizes and lower parasite loads.

The findings in this study demonstrate the potential of pristane as an adjuvant for antileishmanial vaccines, effectively inducing protective Th1 responses. However, safety assessments, dosage optimization and evaluation in non-human primates are recommended to confirm its suitability and enhance vaccine efficacy.