Bluetongue virus: European Community inter-laboratory comparison tests to evaluate ELISA and RT-PCR detection methods

Area of Science:

• Veterinary Virology
• Molecular Diagnostics
• Immunoserology

Background:

• Bluetongue virus (BTV) poses a significant threat to livestock in Europe.
• Accurate diagnostic assays are essential for BTV surveillance and control.
• National reference laboratories require validated methods for reliable BTV detection.

Purpose of the Study:

• To evaluate the sensitivity and specificity of 'in-house' ELISA and RT-PCR assays used by European national reference laboratories for BTV detection.
• To assess the performance of these assays in detecting antibodies and RNA from various BTV serotypes, including the emerging BTV-8 strain.
• To provide crucial diagnostic sensitivity and specificity data for available BTV detection methods.

Main Methods:

• Two inter-laboratory comparison tests (ring trials) were conducted in 2006.
• Laboratories used 'in-house' competitive ELISA (C-ELISA) and RT-PCR (real-time and conventional) assays.
• Samples included antisera and EDTA blood from experimentally infected animals and panels covering 24 BTV serotypes.

Main Results:

• All C-ELISAs detected circulating European BTV serotypes (1, 2, 4, 8, 9, 16), with some variability for BTV-19.
• C-ELISAs detected BTV-8 antibodies in cattle and sheep by 21 days post-infection (dpi), with most detecting by 9 dpi (cattle) and 8 dpi (sheep).
• Real-time RT-PCR assays demonstrated higher sensitivity than conventional RT-PCR for BTV-8 RNA detection, identifying viral RNA as early as 2 dpi (cattle) and 3 dpi (sheep).

Conclusions:

• National reference laboratories in the European Community possess capable assays for detecting BTV antibodies and RNA.
• The study provides valuable sensitivity and specificity data for ELISA and RT-PCR methods used in BTV diagnostics.
• These findings support the ongoing efforts for effective bluetongue virus surveillance and disease management within Europe.