Dengue NS1 antigen detection: a useful tool in early diagnosis of dengue virus infection.
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.
Datta
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Department of Clinical Microbiology, Sir Ganga Ram Hospital, Rajinder Nagar, New Delhi - 110 060, India.
Wattal
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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
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