title: Assessing positivity and circulating levels of NS1 in samples from a 2012 dengue outbreak in Rio de Janeiro, Brazil.
abstract: Dengue virus (DENV) represents a major threat to public health worldwide. Early DENV diagnosis should not only detect the infection but also identify patients with a higher likelihood to develop severe cases. Previous studies have suggested the potential for NS1 to serve as a viral marker for dengue severity. However, further studies using different sera panels are required to confirm this hypothesis. In this context, we developed a lab-based ELISA to detect and quantitate NS1 protein from the four DENV serotypes and from primary and secondary cases. This approach was used to calculate the circulating NS1 concentration in positive samples. We also tested the NS1 positivity of DENV-positive samples according to the Platelia Dengue NS1 Ag assay. A total of 128 samples were positive for DENV infection and were classified according to the WHO guidelines. The overall NS1 positivity was 68% according to the Platelia assay, whereas all samples were NS1-positive when analyzed with our lab-based ELISA. Fifty-four samples were positive by PCR, revealing a co-circulation of DENV1 and DENV4, and the NS1 positivity for DENV4 samples was lower than that for DENV1. The circulating NS1 concentration ranged from 7 to 284 ng/mL. Our results support previous data indicating the low efficiency of the Platelia assay to detect DENV4 infection. Moreover, this work is the first to analyze NS1 antigenemia using retrospective samples from a Brazilian outbreak.
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Diego
authors.initials: D
authors.lastname: Allonso
authors.affiliation: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Marcelo D F
authors.initials: MD
authors.lastname: Meneses
authors.affiliation: Laboratorio Central Noel Nütels (LACEN), Rio de Janeiro, RJ, Brazil.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Fernandes
authors.affiliation: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Davis F
authors.initials: DF
authors.lastname: Ferreira
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Mohana-Borges
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000956:Antigens, Viral / Q000097:blood*; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003715:Dengue / Q000097:blood* / Q000453:epidemiology* / Q000473:pathology / Q000821:virology; D003716:Dengue Virus / Q000302:isolation & purification / Q000378:metabolism; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000097:blood; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D012189:Retrospective Studies; D012703:Serotyping; D012720:Severity of Illness Index; D017361:Viral Nonstructural Proteins / Q000097:blood* / Q000235:genetics / Q000276:immunology; D055815:Young Adult
chemical_list: D000956:Antigens, Viral; C079340:NS1 protein, Dengue virus type 2; C546113:NS1 protein, Dengue virus type 3; C082515:NS1 protein, dengue-1 virus; D012367:RNA, Viral; D011994:Recombinant Proteins; D017361:Viral Nonstructural Proteins