Immunoprophylactic effect of r-Leishmania braziliensis HSP70 in experimental cutaneous leishmaniasis.

ALVAREZ MOYA, A; BRACAMONTE, E; HOYOS, C; UNCOS, AD; ACUÑA , L; BASOMBRÍO, MA; BARROSO, PA; MARCO, JD

Paraná

Congreso; LIV reunión anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular.; 2018

Tegumentary leishmaniasis (TL) is a disease caused by parasites of the genus Leishmania. There are no effective human vaccines and the use of recombinant proteins seems to be a safe strategy. Seroproteomic approaches were applied for the selection of Leishmania (Viannia) braziliensis antigen as immunoprophylactic candidates. A recombinant HSP70 antigen (rAg) was evaluated on a model of TL using Al(OH)3 as adjuvant (Adj). BALB/c mice were distributed in four groups: 1) rAg (49.5μg) + Adj (1mg), 2) rAg alone, 3) Adj alone and 4) control with PBS (Buf). They were challenged in the footpad with L. (L.) amazonensis promastigotes and then DTH was measured at 24, 48 and 72h. The footpad swelling (FPS) was measured weekly until euthanasia in the 16thweek post-infection (PI). The footpad lesions were taken to measure parasite load. IgG1 and IgG2a were quantified before challenge and at 16th week PI. DTH in group rAg+Adj at 24h (0.2±0.04 mm) was higher (p>0.043) than Adj (0.14±0.05mm). At week 8 PI, the FPS in group rAg+Adj was 0.78±0.29mm, lower (p>0.006) than Adj (1.67±0.26mm) and rAg (2.07±0.9mm). However, these differences did not last until week 16 PI and parasite load did not show any differences. Before challenge, the levels of IgG1 (DO492=0.9±0.04) and IgG2a (DO492=0.17±0.11) of the two immunized groups were higher (p>0.0009) as compared to Buf. These differences persisted until euthanasia. The immunization with the rAg was not protective, inducing high levels of IgG1, associated with a non- healing Th2 response, as it was observed in humans. But, combined with Adj, the exacerbated FPS was controlled over time; despite it did not affect antibody levels.