The cured immune phenotype achieved by treatment of visceral leishmaniasisin the BALB/c mouse with a nonionic surfactant vesicular formulation of sodium stibogluconate does not protect against reinfection

Single-dose treatment with sodium stibogluconate solution (SSG) and treatme nt with a nonionic surfactant vesicular formulation of sodium stibogluconat e (SSG-NIV) were compared for the ability to protect BALB/c mice against in fection with Leishmania donovani, Prophylactic treatment with SSG-NIV prote cted against infection, although its effects were time and organ dependent; protection was not obtained with SSG, Protection against reinfection with L. donovani was observed only in mice cured by treatment with SSG-NIV, Howe ver, this protective effect was probably due to the presence of residual dr ug rather than an immune effect, since prophylactic SSG-NIV treatment gave similar results, Transfer of-enriched spleen. T-cell populations from L, do novani-infected mice or from infected SSG-NIV-treated mice gave no protecti on against L. donovani infection in the recipients. T cells from infected m ice, but not from infected SSG-NIV-treated mice, were infectious to recipie nts. SSG-NIV treatment was equally effective against visceral leishmaniasis in immunocompetent and SCID mice, whereas SSG treatment was less effective in the latter. The results of this study suggest that the high antileishma nial activity of SSG-NIV is due to favorable modification of SSG delivery a nd does not require a fully functional immune response. Cure of visceral le ishmaniasis by SSG-NIV treatment in the BALB/c mouse did not protect agains t reinfection.