title: Comparative proteomics and glycoproteomics of plasma proteins in Indian visceral leishmaniasis.
abstract: BACKGROUND
  Visceral leishmaniasis (VL) is a deadly parasitic diseases caused by Leishmania donovani; it is a major health problem in many countries. A lack of proper understanding of the disease biology, poor diagnostic methods and increasing drug resistance are the main reasons for the growing burden of VL infection. Comparative plasma proteomics are a relatively useful technique that can be used to investigate disease-associated alterations that can help in understanding host responses against pathogens, and might be useful in disease management and diagnosis.
  
  
  RESULTS
  In this study, a comparative proteomics and glycoproteomics approach using 2DE and 2D-DIGE was employed between early diagnosed VL patients of all age groups and healthy endemic and non-endemic controls in order to aid the recognition of disease-associated alterations in host plasma. Comparative proteomics was performed by the depletion of seven highly abundant plasma proteins. Comparative glycoproteomics was performed by the depletion of albumin and IgG, followed by purification of plasma glycoproteins using a multi lectin affinity column. From these two approaches, 39 differentially expressed protein spots were identified and sequenced using MALDI-TOF/TOF mass spectrometry. This revealed ten distinct proteins that appeared in multiple spots, suggesting micro-heterogeneity. Among these proteins, alpha-1-antitrypsin, alpha-1-B glycoprotein and amyloid-A1 precursor were up-regulated, whereas vitamin-D binding protein, apolipoprotein-A-I and transthyretin were down-regulated in VL. Alterations in the levels of these proteins in VL-infected plasma were further confirmed by western blot and ELISA.
  
  
  CONCLUSIONS
  These proteins may be involved in the survival of parasites, resisting neutrophil elastase, and in their multiplication in macrophages, potentially maintaining endogenous anti-inflammatory and immunosuppressive conditions. Consequently, the results of this study may help in understanding the host response against L.donovani, which could help in the discovery of new drugs and disease management. Finally, these alterations on protein levels might be beneficial in improving early diagnosis considering those as biomarkers in Indian VL.
authors.affiliation: Cancer Biology and Inflammatory Disorder Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032 India.
authors.forename: Arup Kumar
authors.initials: AK
authors.lastname: Bag
authors.affiliation: Crystallography & Molecular Biology, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, 700 064 India.
authors.forename: Sutapa
authors.initials: S
authors.lastname: Saha
authors.affiliation: Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221005 India.
authors.forename: Shyam
authors.initials: S
authors.lastname: Sundar
authors.affiliation: Department of Tropical Medicine, School of Tropical Medicine, Chittaranjan Avenue, Kolkata, 700073 India.
authors.forename: Bibhuti
authors.initials: B
authors.lastname: Saha
authors.affiliation: Crystallography & Molecular Biology, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, 700 064 India.
authors.forename: Abhijit
authors.initials: A
authors.lastname: Chakrabarti
authors.affiliation: Cancer Biology and Inflammatory Disorder Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032 India.
authors.forename: Chitra
authors.initials: C
authors.lastname: Mandal
keywords: 2D-DIGE; M-LAC column; MALDI-TOF/TOF mass spectrometry; MARS column; Plasma glycoproteomics; Visceral leishmaniasis