The adjuvant of the
FML-
vaccine against murine and canine
visceral leishmaniasis, the Riedel de Haen
saponin mixture, was fractionated by ion exchange chromatography on
DEAE-cellulose to afford one TLC homogeneous Quillaja saponaria Molina
QS21 saponin fraction (18.0%), a mixture of two deacylsaponins (19.4%),
sucrose (39.9%),
sucrose and
glucose (19.7%),
rutin (0.8%) and
quercetin (2.2%), that were identified by comparison of 1H and 13C NMR spectroscopy. The
QS21 shows the typical
aldehyde group in C-23 (65% equatorial) and a normonoterpene moiety acylated in C-28. The deacylsaponins show the
aldehyde group but do not have the normonoterpene moiety. Balb/c mice were vaccinated with 150 microg of
FML antigen of Leishmania donovani and 100 microg of each obtained fraction and further challenged by
infection with 10(8) amastigotes of Leishmania chagasi. The safety analysis and the effect on humoral and cellular immune responses and in clinical signs showed that the
QS21 saponin and the deacylsaponins are the most active adjuvant compounds of the Riedel the Haen
saponin mixture. Both induced the highest and non-significantly different increases in DTH, CD4+ T lymphocytes in spleen, IFN-gamma in vitro,
body weight gain and the most pronounced reduction of parasite burden in liver (95% for
QS21 and 86% for deacylsaponins; p>0.05). While the
QS21 showed mild toxicity, significant adjuvant effect on the anti-
FML humoral response before and after
infection, and decrease in liver relative weight, the deacylsaponins showed no toxicity, less
haemolysis and antibody and DTH responses increased mainly after
infection, still inducing a stronger Leishmania-specific in vitro splenocyte proliferation. Our results confirm in the Riedel de Haen
saponin extract the presence of deacylsaponins normonoterpene-deprivated which are non-toxic and capable of inducing a specific and strong immunoprotective response in vaccination against murine
visceral leishmaniasis.