Ubiquitin conjugation of open reading frame F DNA vaccine leads to enhanced cell-mediated immune response and induces protection against both antimony-susceptible and -resistant strains of Leishmania donovani.
Resistance of Leishmania donovani to sodium antimony gluconate has become a critical issue in the current, prolonged epidemic in India. Hence, there is an urgent need for a vaccine that is protective against both antimony-susceptible and -resistant strains of L. donovani. The multigene LD1 locus located on chromosome 35 of Leishmania is amplified in approximately 15% of the isolates examined. The open reading frame F (ORFF), a potential vaccine candidate against visceral leishmaniasis, is part of the multigene LD1 locus. ORFF was expressed as a chimeric conjugate of ubiquitin to elicit an Ag-specific cell-mediated immune response. Analysis of the cellular immune responses of ubiquitin-conjugated ORFF (UBQ-ORFF) DNA-immunized, uninfected BALB/c mice demonstrated that the vaccine induced enhanced IFN-gamma-producing CD4(+) and CD8(+) T cells compared with nonubiquitinated ORFF DNA vaccine. Higher levels of IL-12 and IFN-gamma and the low levels of IL-4 and IL-10 further indicated that the immune responses with UBQ-ORFF were mediated toward the Th1 rather than Th2 type. Infection of immunized mice with either the antimony-susceptible (AG83) or -resistant (GE1F8R) L. donovani strain showed that UBQ-ORFF DNA vaccine induced higher protection when compared with ORFF DNA. UBQ-ORFF DNA-immunized and -infected mice showed a significant increase in IL-12 and IFN-gamma and significant down-regulation of IL-10. High levels of production of nitrite and superoxide, two macrophage-derived oxidants that are critical in controlling Leishmania infection, were observed in protected mice. The feasibility of using ubiquitinated-conjugated ORFF DNA vaccine as a promising immune enhancer for vaccination against both antimony-susceptible and -resistant strains of L. donovani is reported.
Sharma
Ankur
A
School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
Madhubala
Rentala
R
D000818:Animals; D000965:Antimony / Q000276:immunology / Q000633:toxicity*; D002478:Cells, Cultured; D004351:Drug Resistance / Q000235:genetics / Q000276:immunology; D005260:Female; D020022:Genetic Predisposition to Disease; D007111:Immunity, Cellular / Q000235:genetics; D007893:Leishmania donovani / Q000235:genetics / Q000276:immunology*; D054332:Leishmaniasis Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D007898:Leishmaniasis, Visceral / Q000276:immunology* / Q000469:parasitology / Q000517:prevention & control*; D051379:Mice; D008807:Mice, Inbred BALB C; D016366:Open Reading Frames / Q000235:genetics / Q000276:immunology; D015800:Protozoan Proteins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology / Q000469:parasitology; D025801:Ubiquitin / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*
D054332:Leishmaniasis Vaccines; C402106:ORFF protein, Leishmania; D015800:Protozoan Proteins; D025801:Ubiquitin; D018074:Vaccines, Conjugate; D019444:Vaccines, DNA; D000965:Antimony