Purification, characterization of O-acetylated sialoglycoconjugates-specific IgM, and development of an enzyme-linked immunosorbent assay for diagnosis and follow-up of indian visceral leishmaniasis patients.
The surface expression of 9-O-acetylated sialic acid (9-OAcSA) is elevated on hematopoietic cells and erythrocytes of visceral leishmaniasis (VL) patients. In this study, we show that VL patients contain elevated levels of IgM antibodies directed against 9-O-acetylated sialoglycoconjugates (9-OAcSG). These antibodies were affinity purified with bovine submaxillary protein as the affinity matrix containing the terminal epitope, 9-OAcSAalpha2-6GalNAc. They also bound to 9-OAcSGs on hematopoietic cells of patients with VL and to epitopes in the cytosol of Leishmania donovani promastigotes. A novel enzyme-linked immunosorbent assay was employed that showed 4-fold higher anti-OAcSG titers in VL patients (n=38), mean +/- S.E.M. being 0.83 +/- 0.09 vs. 0.21 +/- 0.04 detected in normal donors (n=20) and patients with cross-reactive diseases such as malaria (n=4) or tuberculosis (n=4). Assay specificity and sensitivity was 100% and 92%, respectively, whereas positive and negative predictive values were 100% and 90%, respectively. Significantly, anti-OAcSG titers declined 30 days after completion of anti-leishmanial treatment, indicating that monitoring of anti-9-OAcSGs may be a valuable alternative toward increasing the efficiency of diagnosis and follow-up of VL.
Bandyopadhyay
Sumi
S
Immunobiology Division, Indian Institute of Chemical Biology, Jadavpur, Kolkata, India.
Chatterjee
Mitali
M
Pal
Santanu
S
Waller
Ross F
RF
Sundar
Shyam
S
McConville
Malcolm J
MJ
Mandal
Chitra
C
D000107:Acetylation; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000032:analysis*; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006001:Glycoconjugates / Q000032:analysis*; D006801:Humans; D007075:Immunoglobulin M / Q000032:analysis*; D007194:India / Q000453:epidemiology; D007893:Leishmania donovani / Q000276:immunology; D007898:Leishmaniasis, Visceral / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology; D008297:Male; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012794:Sialic Acids / Q000032:analysis* / Q000276:immunology
D000888:Antibodies, Anti-Idiotypic; D006001:Glycoconjugates; D007075:Immunoglobulin M; D012794:Sialic Acids