An international external quality assessment of nucleic acid amplification of herpes simplex virus.
BACKGROUND
There is an increasing awareness of the need for external quality control of diagnostic virology.


OBJECTIVE
To assess the quality of nucleic acid amplification tests (NAT) of herpes simplex within Europe.


METHODS
Herpes simplex virus (HSV) proficiency panels were produced at the Swedish Institute for Infectious Disease Control on behalf of the European Union Concerted Action for Quality Control of Nucleic Acid Amplification in 1999 and 2000. Nine reference laboratories evaluated the production process. Each panel consisted of 12 coded samples with various concentrations of inactivated, freeze-dried HSV type 1 (HSV-1), and HSV type 2 (HSV-2), or negative controls. Positive samples included HSV-1 and HSV-2 in a range of concentrations (2 x 10(2) to 2 x 10(7) genome copies per ml) similar to those found in cerebrospinal fluids from patients with HSV encephalitis.


RESULTS
Sixty-six participants reported a total of 76 data sets for panel 1, and 71 reported 78 data sets for panel 2. The majority of the participants employed qualitative 'in-house' polymerase chain reaction (PCR) methods, either in a single, nested or semi-nested format. For panel 2, 9 laboratories reported use of 'real-time' PCR in contrast to 3 for panel 1. Three laboratories submitted quantitative results on both panels. Thirty percent of the data sets had correct results for the entire panel 1. In 6 data sets (8%) a total of 11 false positive results were reported. For panel 2, 28% of the data sets had correct result. Nineteen false positive results were reported in 14 data sets (18%), but most of the incorrect results reflected a lack of test sensitivity.


CONCLUSIONS
The relatively high frequency of false positive results and the large number of false-negative results, albeit at low copy number, stress the need for improvement in the quality of HSV NAT and for external quality control programmes.
Schloss
Lottie
L
Quality Control Concerted Action, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, United Kingdom. lottie.schloss@smi.ki.se
van Loon
Anton M
AM
Cinque
Paola
P
Cleator
Graham
G
Echevarria
José-Manuel
JM
Falk
Kerstin I
KI
Klapper
Paul
P
Schirm
Jurjen
J
Vestergaard
Bent Faber
BF
Niesters
Hubert
H
Popow-Kraupp
Therese
T
Quint
Wim
W
Linde
Annika
A
D005188:False Negative Reactions; D005189:False Positive Reactions; D006561:Herpes Simplex / Q000175:diagnosis* / Q000235:genetics; D006801:Humans; D007391:International Cooperation; D007753:Laboratories; D016133:Polymerase Chain Reaction / Q000379:methods* / Q000592:standards*; D011785:Quality Assurance, Health Care; D011786:Quality Control; D012367:RNA, Viral / Q000097:blood; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018139:Simplexvirus / Q000302:isolation & purification*
D012367:RNA, Viral