Page 84 - Resúmen - XXV Congreso Latinoamericano de Parasitología - FLAP

tGPI-mucins contain immunodominant -Gal glycotopes, such as Gal(1,3)Gal(1,4)GlcNAc (Gal3LN)
and several branched ones, which induce high levels of protective, lytic anti--Gal antibodies that control
parasitemia in both acute and chronic phases of CD. Recently, we have demonstrated that a synthetic
neoglycoprotein (NGP) containing Ga3LN induces 100% survival following parasite challenge in 1,3-
galactosyltransferase-knockout (1,3-GalT-KO) mouse model, which mimics the human response against
-Gal glycotopes that are absent in humans and Old-World nonhuman primates. These α-Gal glycotopes
are also highly conserved throughout T. cruzi genotypes and field strains, since patients with chronic CD
from very distinct endemic and nonendemic regions universally produce high levels of T. cruzi-specific anti-
-Gal antibodies. Here, using the reversed immunoglycomic approach, we have identified, synthesized,
and evaluated the efficacy of several -Gal-based neoglycoproteins (-Gal-NGPs) as potential biomarkers
for early assessment of chemotherapy outcomes in chronic CD in various preclinical and clinical studies.
We also assessed these synthetic -Gal-NGPs as vaccine candidates in both 1,3-GalT-KO mouse and
nonhuman primate models of CD. Taken together, our data strongly indicate that -Gal-NGPs are very
promising BMKs not only for early evaluation of chemotherapeutic outcomes but also as potential
prophylactic vaccine candidates.

Cutaneous leishmaniasis (CL) caused by L. braziliensis is characterized by a range of clinical presentations,
including a localized cutaneous ulcer to mucocutaneous or disseminated disease. Treatment is still based
on the use of antimonials and cure is clinically defined as the complete healing of the dermal ulcer. No
molecular biomarkers (BMKs) of active disease or cure are available. In L. major, highly abundant type-II
GIPL-1, -2, and -3 are capped with terminal, nonreducing -galactofuranosyl (-Galf) or -galactopyranosyl
(-Galp) residue (Galƒ-R, Galpα(1,3)Galƒ-R, and Galp(1,6)Galp(1,3)Galƒ-R, respectively; where R
is the remaining glycosylphosphatidylinositol anchor). These GIPLs are conserved throughout the
parasite’s life cycle, are highly abundant in the amastigotes and, notably, are highly immunogenic to
humans. Based on this premise, we evaluated synthetic Type-II GIPL-derived structures against a panel of
sera obtained from patients with localized cutaneous (LCL), mucosal (MCL), or disseminated (DCL)
v
leishmaniasis from an area in Brazil endemic for L. braziliensis. Patients were treated with Sb (Glucantime;
i.v., 20 mg/kg/d, 20 d). Sera were obtained at the time of diagnosis and following clinical confirmation of
cure, and were tested by chemiluminescent ELISA, using as antigens synthetic neoglycoproteins (NGPs)
derived from type-II GIPL-1, -2, or -3. We observed that the a GIPL-derived NGP (NGP28b) strongly reacted
with sera from LCL patients during the active phase of disease, whereas titers significantly decreased upon
lesion healing. In contrast, antibody titers to NGP28b were reduced in MCL patients, regardless of active
or cured disease. Reactivity to NGP28b was absent in sera from healthy controls or Chagas disease
patients. Our data indicate that a Type-II GIPL-derived -Gal-containing NGP from L. major is recognized
by sera from patients L. braziliensis CL and positive serology to terminal α-Gal residues may act as a BMK
of active disease and cure. Funding: National Institutes of Health, CAPES, FIOCRUZ, UFBA, and Robert
J. Kleberg, Jr. and Helen C. Kleberg Foundation.

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RESÚMENES DE charlas magistrales