External quality control assessment in PCR diagnostics of dengue virus infections.
BACKGROUND
Increased travelling to countries endemic for dengue fever (DF) demands efficient laboratory diagnostics. Nucleic acid amplification techniques (NAT) are now frequently used for rapid diagnosis of imported viral diseases. Different PCR systems are available.


OBJECTIVE
In order to assess the quality of molecular diagnostics of dengue virus infections, an external quality assurance (EQA) in PCR diagnostics was conducted.


METHODS
A panel of 10 human plasma samples was prepared and spiked with dengue virus types DEN-1 to DEN-4. In addition, a 10-fold dilution series (1:10-1:10(4) ) of DEN-3 virus was included. The panel was pre-tested by nested RT-PCR, in-house real-time PCR, and a commercial real-time PCR kit. The samples were inactivated by gamma irradiation and shipped in freeze dried state. Thirteen laboratories, within the European network for the diagnostics of imported viral diseases (ENIVD) took part using either single-round, nested, or real-time RT-PCR methods. Two laboratories used two methods in parallel, summarising up to 15 comparable results.


RESULTS
33-100% correct results were achieved. All laboratories detected DEN-2 correctly, followed by DEN-1 (14 positive results of 15), DEN-3 (12/15) and DEN-4 (11/15). Testing of the serial dilution revealed low sensitivity in many labs, with results ranging from 33 to 80% of correctly tested samples.


CONCLUSIONS
The EQA gives a feedback of the quality of the RT-PCR system used by each respective laboratory. The different test systems and amplification conditions demonstrate the importance of external quality control measures.
Lemmer
Karin
K
Robert Koch-Institut, Nordufer 20, 13353 Berlin, Germany.
Donoso Mantke
Oliver
O
Bae
Hi-Gung
HG
Groen
Jan
J
Drosten
Christian
C
Niedrig
Matthias
M
D000818:Animals; D002522:Chlorocebus aethiops; D003715:Dengue / Q000175:diagnosis* / Q000821:virology; D003716:Dengue Virus / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D011786:Quality Control; D012367:RNA, Viral / Q000097:blood* / Q000302:isolation & purification; D011933:Reagent Kits, Diagnostic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014709:Vero Cells
D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic