Follow-up on diagnostic proficiency of laboratories equipped to perform orthopoxvirus detection and quantification by PCR: the second international external quality assurance study.
Two years after the first external quality assurance study on bioterrorism-relevant viruses, we have conducted a follow-up study on orthopoxvirus detection by PCR. Thirty-three laboratories (27 European, 4 Austral-Asian, and 2 American) participated. Samples contained 0 to 40,000,000 DNA copies of lyophilized monkeypox, cowpox, and vaccinia virus per ml. Laboratories achieved a >80% detection chance above 56,234 copies per ml. Global sensitivity was not significantly improved over that of the first study. Twenty-seven and 9 participants, respectively, were able to genotype and quantify virus. Four of 27 genotyping results were incorrect. Quantification accuracy was significantly better for vaccinia virus than for the other viruses. False-positive results occurred in 22 (11.8%) of all 186 tests on negative samples, but 18 of these were contributed by only five laboratories. Fifty-five percent of laboratories could appropriately detect PCR inhibition. The use of either real-time PCR or commercial diagnostic kits had significant positive influence on laboratory performance.
Niedrig
Matthias
M
Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht Str. 74, 20359 Hamburg, Germany. drosten@bni-hamburg.de
Meyer
Hermann
H
Panning
Marcus
M
Drosten
Christian
C
D019411:Clinical Laboratory Techniques; D004279:DNA, Viral / Q000097:blood; D005500:Follow-Up Studies; D006801:Humans; D007391:International Cooperation; D007753:Laboratories / Q000592:standards*; D018155:Orthopoxvirus / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D011213:Poxviridae Infections / Q000821:virology; D011786:Quality Control; D011933:Reagent Kits, Diagnostic / Q000592:standards*
D004279:DNA, Viral; D011933:Reagent Kits, Diagnostic