title: Dengue NS1 antigen detection: a useful tool in early diagnosis of dengue virus infection.
abstract: OBJECTIVE
  This study was undertaken to evaluate the efficacy of NS1 antigen (Ag) assay as an early marker for dengue virus (DV) infection.
  
  
  METHODS
  Group I evaluated the performance of NS1 antigen (Ag) assay in comparison to MAC-ELISA and their detection rate when performed together in a single sample. Six hundred acute/early convalescent sera were screened by both the assays. Group II evaluated the efficacy of a single assay in 30 acute phase sera of paediatric OPD patients screened only by NS1 Ag assay. Group III evaluated the specificity of NS1 assay in comparison to MAC-ELISA on 40 samples included as controls.
  
  
  RESULTS
  In Group I, 140 (23.3%) and 235 (39.1%) samples were positive by NS1 assay and MAC-ELISA respectively. The detection rate increased to 320 (53.3%) when both the assays were used together on a single sample. NS1 Ag positivity varied from 71.42% to 28.4% in acute and early convalescent sera, conversely IgM detection rate was 93.61% and 6.38% in early convalescent and acute phase sera respectively (P < 0.0001). In Group II, 66.66% (20) samples were positive by NS1 assay. All the samples in Group III were negative showing 100% specificity of both the assays.
  
  
  CONCLUSIONS
  NS1 Ag assay holds promise in early diagnosis of dengue infection. When used in combination with MAC-ELISA on a single sample it significantly improves the diagnostic algorithm without the requirement of paired sera.
authors.affiliation: Department of Clinical Microbiology, Sir Ganga Ram Hospital, Rajinder Nagar, New Delhi - 110 060, India.
authors.forename: S
authors.initials: S
authors.lastname: Datta
authors.forename: C
authors.initials: C
authors.lastname: Wattal
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D003715:Dengue / Q000175:diagnosis*; D003716:Dengue Virus / Q000302:isolation & purification*; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D007223:Infant; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D017361:Viral Nonstructural Proteins / Q000097:blood*; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D007075:Immunoglobulin M; C079340:NS1 protein, Dengue virus type 2; C082515:NS1 protein, dengue-1 virus; D017361:Viral Nonstructural Proteins