Gene deleted live attenuated Leishmania vaccine candidates against visceral leishmaniasis elicit pro-inflammatory cytokines response in human PBMCs

Sci Rep. 2016 Sep 14:6:33059. doi: 10.1038/srep33059.

Abstract

Currently no effective vaccine is available for human visceral leishmaniasis(VL) caused by Leishmania donovani. Previously, we showed that centrin1 and p27gene deleted live attenuated Leishmania parasites (LdCen1(-/-) and Ldp27(-/-)) are safe, immunogenic and protective in animal models. Here, to assess the correlates of protection, we evaluated immune responses induced by LdCen1(-/-) and Ldp27(-/-) in human blood samples obtained from healthy, healed VL (HVL), post kala-azar dermal leishmaniasis(PKDL) and VL subjects. Both parasites infected human macrophages, as effectively as the wild type parasites. Further, LdCen1(-/-) and Ldp27(-/-) strongly stimulated production of pro-inflammatory cytokines including, IL-12, IFN-γ, TNF-α, IL-2, IL-6 and IL-17 in the PBMCs obtained from individuals with a prior exposure to Leishmania (HVL and PKDL). There was no significant stimulation of anti-inflammatory cytokines (IL-4 and IL-10). Induction of Th1 biased immune responses was supported by a remarkable increase in IFN-γ secreting CD4(+) and CD8(+) T cells and IL-17 secreting CD4(+) cells in PBMCs from HVL cases with no increase in IL-10 secreting T cells. Hence, LdCen1(-/-) and Ldp27(-/-) are promising as live vaccine candidates against VL since they elicit strong protective immune response in human PBMCs from HVL, similar to the wild type parasite infection, mimicking a naturally acquired protection following cure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / immunology
  • Female
  • Gene Knockdown Techniques
  • Genes, Protozoan*
  • Humans
  • Leishmania donovani* / genetics
  • Leishmania donovani* / immunology
  • Leishmaniasis Vaccines* / genetics
  • Leishmaniasis Vaccines* / immunology
  • Leishmaniasis, Visceral* / genetics
  • Leishmaniasis, Visceral* / immunology
  • Leishmaniasis, Visceral* / prevention & control
  • Leukocytes, Mononuclear* / immunology
  • Leukocytes, Mononuclear* / parasitology
  • Male
  • Monokines / immunology
  • Vaccines, Attenuated / genetics
  • Vaccines, Attenuated / immunology

Substances

  • Cell Cycle Proteins
  • Leishmaniasis Vaccines
  • Monokines
  • Vaccines, Attenuated