Gabriane Nascimento Porcino
Statement of the Problem: Humoral immune response is detrimental in the pathogenesis of L. infantum in dogs, and antibody titer correlates with more severe clinical signs of the disease. Studies correlate IgG subclass and symptomatology to disease, but IgG N-glycosylation is poorly explored. Changes in the glycosylation profile may promote proinflammatory or antiinflammatory responses, depending on which glycan is altered (fucose, mannose, galactose, and sialic acid). It has been shown by the group that the IgG glycosylation profile changes in humans infected with L. infantum. However, the glycosylation profile in humans and dogs is different, and dogs have a higher amount of fucose. Our objective was to evaluate whether there is a difference in the fucosylation profile in the IgG Fc portion of specific anti-Leishmania antibodies to understand the pathogenesis. Methodology & Theoretical Orientation: We used Enzyme-Linked Lectin Assay (ELLA) with L. infantum antigens treated with different enzymes (a1-2, 4, 6 fucosidase O (New England BioLabs®), IgGZERO LE (Genovis®) and PNGase F (New England BioLabs®)) to deglycosylation glycan residues and compare antibody titers to those found in the ELISA (Enzyme-Linked Immunosorbent Assay) from 45 dogs serum samples (15 symptomatic, 15 asymptomatic and 15 uninfected) provided by prof. Roque Pacheco de Almeida, Universidade Federal de Sergipe. Western blotting was performed to confirm the deglycosylation of antigen. Findings: L. infantum promastigote in the metacyclic phase shows fucose residues, and PNGase F may be an option for antigen deglicosylation. The symptomatic and asymptomatic groups had statistically higher antibody titers compared to the control group. The serology of symptomatic, asymptomatic and controls dogs did not differ regarding the amount of fucose in different antigens under the conditions employed. Conclusion & Significance: PNGase F should be used in antigen deglicosylation in different concentrations and more tests are necessary to see the difference in fucosylation profile in the Fc portion of IgG for specific anti-Leishmania antibodies.
