title: Use of a novel chagas urine nanoparticle test (chunap) for diagnosis of congenital chagas disease.
abstract: BACKGROUND
  Detection of congenital T. cruzi transmission is considered one of the pillars of control programs of Chagas disease. Congenital transmission accounts for 25% of new infections with an estimated 15,000 infected infants per year. Current programs to detect congenital Chagas disease in Latin America utilize microscopy early in life and serology after 6 months. These programs suffer from low sensitivity by microscopy and high loss to follow-up later in infancy. We developed a Chagas urine nanoparticle test (Chunap) to concentrate, preserve and detect T. cruzi antigens in urine for early, non-invasive diagnosis of congenital Chagas disease.
  
  
  RESULTS
  This is a proof-of-concept study of Chunap for the early diagnosis of congenital Chagas disease. Poly N-isopropylacrylamide nano-particles functionalized with trypan blue were synthesized by precipitation polymerization and characterized with photon correlation spectroscopy. We evaluated the ability of the nanoparticles to capture, concentrate and preserve T. cruzi antigens. Urine samples from congenitally infected and uninfected infants were then concentrated using these nanoparticles. The antigens were eluted and detected by Western Blot using a monoclonal antibody against T. cruzi lipophosphoglycan. The nanoparticles concentrate T. cruzi antigens by 100 fold (western blot detection limit decreased from 50 ng/ml to 0.5 ng/ml). The sensitivity of Chunap in a single specimen at one month of age was 91.3% (21/23, 95% CI: 71.92%-98.68%), comparable to PCR in two specimens at 0 and 1 month (91.3%) and significantly higher than microscopy in two specimens (34.8%, 95% CI: 16.42%-57.26%). Chunap specificity was 96.5% (71/74 endemic, 12/12 non-endemic specimens). Particle-sequestered T. cruzi antigens were protected from trypsin digestion.
  
  
  CONCLUSIONS
  Chunap has the potential to be developed into a simple and sensitive test for the early diagnosis of congenital Chagas disease.
authors.affiliation: Department of International Health, Johns Hopkins University, Bloomberg School of Hygiene and Public Health, Baltimore, Maryland, United States of America; Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Yagahira E
authors.initials: YE
authors.lastname: Castro-Sesquen
authors.affiliation: Department of International Health, Johns Hopkins University, Bloomberg School of Hygiene and Public Health, Baltimore, Maryland, United States of America.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Gilman
authors.affiliation: Department of International Health, Johns Hopkins University, Bloomberg School of Hygiene and Public Health, Baltimore, Maryland, United States of America.
authors.forename: Gerson
authors.initials: G
authors.lastname: Galdos-Cardenas
authors.affiliation: Hospital Universitario Japonés, Santa Cruz, Bolivia.
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Ferrufino
authors.affiliation: Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Sánchez
authors.affiliation: Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Edward
authors.initials: E
authors.lastname: Valencia Ayala
authors.affiliation: Center for Applied Proteomics and Molecular Medicine, George Mason University, Fairfax, Virginia, United States of America.
authors.forename: Lance
authors.initials: L
authors.lastname: Liotta
authors.affiliation: Global Health Sciences, Department of Epidemiology and Biostatistics School of Medicine, University of California, San Francisco, California, United States of America.
authors.forename: Caryn
authors.initials: C
authors.lastname: Bern
authors.affiliation: Center for Applied Proteomics and Molecular Medicine, George Mason University, Fairfax, Virginia, United States of America.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Luchini
mesh_terms: D000178:Acrylamides; D000953:Antigens, Protozoan / Q000652:urine*; D015153:Blotting, Western; D014355:Chagas Disease / Q000151:congenital / Q000175:diagnosis*; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007843:Latin America; D053758:Nanoparticles; D012680:Sensitivity and Specificity; D014349:Trypanosoma cruzi / Q000276:immunology* / Q000302:isolation & purification
chemical_list: D000178:Acrylamides; D000953:Antigens, Protozoan; C067295:N-isopropylacrylamide