Quality control assessment for the PCR diagnosis of tick-borne encephalitis virus infections

Abstract 

Background

Reverse transcriptase-polymerase chain reaction (RT-PCR) is an efficient method for the early detection of tick-borne encephalitis virus (TBEV) RNA in blood and serum samples taken prior to the appearance of antibodies. Improved diagnostics are critical for optimally detecting and managing TBE infections and quality control measures are therefore essential.

Objective

To assess the diagnostic quality of laboratories by performing an external quality assurance (EQA) programme for the molecular detection of TBE infections.

Study design

A panel of 12 prepared human plasma samples were distributed and tested for the presence of TBEV-specific RNA. The panel comprised eight samples spiked with different TBEV strains of European, Siberian and Far Eastern subtypes, and included a 10-fold dilution series. Two specificity controls consisted of a sample with Louping ill virus (LIV) and a sample with a pool of four other flaviviruses, and two negative control samples were further included.

Results

Twenty-three laboratories from 16 European and 2 non-European countries participated in this EQA programme. Only two participants correctly identified all samples. Nine laboratories correctly identified 75.0–91.7% of the samples; seven laboratories correctly identified 54.5–66.7% and five laboratories correctly identified ≤50%.

Conclusions

The EQA programme provides information on the quality of the RT-PCR methods used by the participating laboratories and indicates that most of these need to improve sensitivity and specificity of their molecular assays for TBEV.

Abbreviations: CNS, central nervous system, CSF, cerebrospinal fluid, DENV, dengue virus, EIA, enzyme immunoassay, ENIVD, European Network for Diagnostics of ‘Imported’ Viral Diseases, EQA, external quality assurance, JEV, Japanese encephalitis virus, LIV, Louping ill virus, NAT, nucleic acid amplification techniques, RT-PCR, reverse transcriptase-polymerase chain reaction, SLEV, St. Louis encephalitis virus, TBE, tick-borne encephalitis, TBEV, tick-borne encephalitis virus, YFV, yellow fever virus

Keywords: Tick-borne encephalitis virus, RT-PCR, EQA, Diagnostic, ENIVD