Intramuscular immunization with p36(LACK) DNA vaccine induces IFN-γ production but does not protect BALB/c mice against Leishmania chagasi intravenous challenge

Abstract

Acute visceral leishmaniasis is a progressive disease caused by Leishmania chagasi in South America. The acquisition of immunity following infection suggests that vaccination is a feasible approach to protect against this disease. Since Leishmania homologue of receptors for activated C kinase (LACK) antigen is of particular interest as a vaccine candidate because of the prominent role it plays in the pathogenesis of experimental Leishmania major infection, we evaluated the potential of a p36(LACK) DNA vaccine in protecting BALB/c mice challenged with L. chagasi. In this study, mice received intramuscular (i.m.) or subcutaneous (s.c.) doses of LACK DNA vaccine. We evaluated the production of vaccine-induced cytokines and whether this immunization was able to reduce parasite load in liver and spleen. We detected a significant production of interferon gamma by splenocytes from i.m. vaccinated mice in response to L. chagasi antigen and to rLACK protein. However, we did not observe a reduction in parasite load neither in liver nor in the spleen of vaccinated animals. The lack of protection observed may be explained by a significant production of IL-10 induced by the vaccine.

Immune response to Leishmania (Leishmania) chagasi infection is reduced in malnourished BALB/c mice

“…in BALB/c mice infected with L. chagasi and the parasite load is increasing in the spleen (Marques-da-Silva et al 2005). Total body weight was analyzed weekly and two weeks after the change in diet, a significant reduction in body weight was observed in mice fed the low protein diet.…”

“…A fragment from each organ was collected to be used for parasite quantification. Quantitative limiting dilution culture was performed as described by Titus et al (1985) and modified by Marques-da-Silva et al (2005). One weighed fragment from each organ (liver and spleen) was homogenized in a tissue grinder and suspended in 500 μL of Grace's Insect Medium (Gibco BRL, Grand Island, NY, USA) supplemented with 10% heat-inactivated foetal calf serum (FCS) (Cripton, Andradina, SP, Brazil), 2 mM L-glutamine (Gibco BRL) and 100 U/mL penicillin G potassium (USB Corporation, Cleveland, OH, USA), pH 6.5 in 96-well flatbottom microtitre plates (160 μL per well).…”

“…Determination of cytokine and NO production -Single-cell suspensions of spleen were obtained by tissue grinder homogenization and processed as described previously (Marques-da-Silva et al 2005). These cells were cultured in 48-well flat-bottom microtitre plates for 72 h in medium (Medium) or stimulated with 50 μg/mL of freeze-thawed L. chagasi antigen (L. chagasi Ag.).…”

Antigenic extracts of Leishmania braziliensis and Leishmania amazonensis associated with saponin partially protects BALB/c mice against Leishmania chagasi infection by suppressing IL-10 and IL-4 production

“…Five post challenge mice were sacrificed and the spleen and liver parasite loads were determined by quantitative limitingdilution culture. Quantitative limiting-dilution culture was performed as previously described with some modifications (Marques-da-Silva et al 2005). Briefly, spleen and liver were harvested and weighed.…”

Microesferas lipídicas encapsuladas com proteínas antigênicas da membrana de Leishmania amazonensis com potencial aplicação terapêutica

“…A região codificadora para a parte protéica da glicoproteína da superfície da Leishmania, a GP63, foi à primeira vacina de plasmídeo produzida contra a leishmaniose (Xu & Liew, 1994 infantum (Ramiro et al, 2003), camundongos BALB/c vacinados com DNA do LACK não foram protegidos contra a infecção pela L. chagasi (Marques-da-Silva et al, 2005).…”