title: A novel reverse transcriptase-polymerase chain reaction based-liquid hybridisation (RT-PCR-LH) assay for early diagnosis of dengue infection.
abstract: BACKGROUND
  Early definitive laboratory diagnosis of dengue is difficult with the tests in routine use at present.
  
  
  OBJECTIVE
  To develop a reverse transcriptase-polymerase chain reaction based liquid hybridisation (RT-PCR-LH) technique for the rapid and early diagnosis of dengue.
  
  
  METHODS
  RT-PCR products of the NS3 gene of dengue virus prototypes and of a few positive sera for dengue virus by culture, were allowed to hybridise in liquid phase with a mixture of dengue specific radiolabelled oligonucleotides. The products were separated by PAGE and visualised by autoradiography. 78 suspected dengue sera were also tested by RT-PCR-LH method, and by IgM-ELISA and HAI tests, for comparison.
  
  
  RESULTS
  Two DNA bands (approximately equal to 470 bp and approximately equal to 455 bp) specific to dengue virus, were observed. RT-PCR-LH assay takes only 24 h. Of the 78 suspected dengue acute sera tested, 45/78 were positive by RT-PCR-LH, 31/78 were positive by IgM-ELISA, and 14/78 had a HAI titre > or = 2560. Duration of fever was known in 72 cases, and infection was detected by RT-PCR-LH in 11/22 of cases with < 5 d fever and by IgM-ELISA in 1/22. In cases with 5 to 15 d fever RT-PCR-LH and IgM-ELISA/HAI titre > or = 2560 detected infection in 30/50 and 27/50 respectively. The 10 sera which were negative by RT-PCR-LH, but were positive by either IgM-ELISA or HAI titre > or = 2560 were all > 5 d fever cases. RT-PCR-LH together with IgM-ELISA were capable of detecting dengue infection in 56/78 of the suspected cases.
  
  
  CONCLUSIONS
  RT-PCR-LH assay developed in this study appears to have an advantage over other diagnostic techniques for the early detection of dengue.
authors.affiliation: Department of Chemistry, Faculty of Science, University of Colombo, Colombo 3. biotech@slt.lk
authors.forename: Maya B
authors.initials: MB
authors.lastname: Gunesekera
authors.forename: Menaka D
authors.initials: MD
authors.lastname: Hapugoda
authors.forename: S
authors.initials: S
authors.lastname: Gunasena
authors.forename: S A S C
authors.initials: SA
authors.lastname: Subasinghe
authors.forename: K B A T
authors.initials: KB
authors.lastname: Bandara
authors.forename: Baldip K
authors.initials: BK
authors.lastname: Khan
authors.forename: W
authors.initials: W
authors.lastname: Abeyewickreme
mesh_terms: D015331:Cohort Studies; D004279:DNA, Viral / Q000032:analysis; D003716:Dengue Virus / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D019595:Severe Dengue / Q000175:diagnosis*
chemical_list: D004279:DNA, Viral