Subcutaneous Immunization of Leishmania HSP70-II Null Mutant Line Reduces the Severity of the Experimental Visceral Leishmaniasis in BALB/c Mice

Abstract

Leishmania infantum parasites cause a severe form of visceral leishmaniasis in human and viscerocutaneous leishmaniasis in dogs. Recently, we reported that immunization with an attenuated L. infantum cell line, lacking the hsp70-II gene, protects against the development of murine cutaneous leishmaniasis. In this work, we analyzed the vaccine potential of this cell line towards the long-term protection against murine visceral leishmaniasis. This model shows an organ-dependent evolution of the disease. The infection can resolve in the liver but chronically affect spleen and bone marrow. Twelve weeks after subcutaneous administration of attenuated L. infantum, Bagg Albino (BALB/c) mice were challenged with infective L. infantum parasites expressing the luciferase-encoding gene. Combining in vivo bioimaging techniques with limiting dilution experiments, we report that, in the initial phase of the disease, vaccinated animals presented lower parasite loads than unvaccinated animals. A reduction of the severity of liver damage was also detected. Protection was associated with the induction of rapid parasite-specific IFN-γ production by CD4+ and CD8+ T cells. However, the vaccine was unable to control the chronic phase of the disease, since we did not find differences in the parasite burdens nor in the immune response at that time point.

Inoculation of the Leishmania infantum HSP70-II Null Mutant Induces Long-Term Protection against L. amazonensis Infection in BALB/c Mice

“…For comparison, we determined the humoral response against the parasite in all mice at the time of challenge (week 12 after vaccination). As expected, at that time only vaccinated mice showed antileishmanial antibodies of both, IgG1 and IgG2a subclasses, in similar levels to these previously described [25,26] (Figure 2). After infectious challenge at the time of the sacrifice, mice from both control groups showed an IgG1 predominant antibody response against the parasite antigens, being the titer of the anti-SLA IgG1 subclass significantly higher than the IgG2a subclass (p = 0.01, low dose; p = 0.0009, high dose) ( Figure 2).…”

“…Vaccination was performed subcutaneously (s.c.) as described in [26]. Briefly, 1 × 10 7 LiΔHSP70-II promastigotes (in 30 µl of phosphate saline buffer (PBS)) were single-administered in the right footpad.…”

“…In this work, we present the effect of vaccination with the attenuated strain of L. infantum LiΔHSP70-II in the subsequent evolution of cutaneous leishmaniasis caused by an infection with L. amazonensis. Vaccination with this attenuated cell line was able to induce an immune response capable of controlling CL [24,25] and VL [26] development caused by L. major or L. infantum infectious challenge in BALB/c mice, respectively. We present here data regarding the evolution of the CL disease as well as the immune response elicited in vaccinated and unvaccinated mice after L amazonensis challenge.…”

Immunogenicity Evaluation of a Novel Lentiviral Vaccine Expressing Multi- Epitope Against of Leishmania Major in BALB/c Mice

“…Three groups of mice were considered and each group was randomly received 8 mice (n= 8), group 1 (rLV-multi-epitope), group 2 (rLV-empty) and group 3 (PBS). The injections were carried out subcutaneously twice during the 1 weeks (with a 3-day interval) with 1×10 6 TU of rLV-multi-epitope (3×10 6 TU/mL) to group 1, and 1×10 6 TU of rLV-empty (1×10 7 TU/ mL) and 0.1 mL PBS to control groups. Finally, three weeks post-immunization of mice, cytokine assay was done.…”

“…Among the types of vaccines studied, the use of DNA vaccines containing the clusters of differentiation (CDs) of whole immunogenic protein has shown promising results. But the use of these antigens in the form of proteins is accompanied with some problems, such as high production cost, short half-life, low immunogenicity, low stimulation of cellular immunity, and cross-allergic reactions (6). Therefore, in the synthesis of vaccines, the use of immunoinformatics tools can be very useful in order to increase the immunogenicity and decrease the adverse reactions (7).…”