Comparison of six commercial ELISAs for the detection of antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) in field serum samples

Porcine reproductive and respiratory syndrome (PRRS) is one of the most common infectious diseases of swine globally. Since the course of PRRS virus (PRRSV) infection is subclinical, laboratory diagnosis is necessary to detect the virus or specific antibodies. The aim of this study was to assess the sensitivity and specificity of IDEXX PRRS X3 Ab Test (IDEXX, USA), Civtest Suis E/S (Hipra, Spain), INgezim PRRS 2.0 (Ingenasa, Spain), VetExpert PRRS Ab ELISA 4.0 (BioNote, Korea), Pigtype PRRSV Ab (Qiagen, Germany) and PrioCHECK PRRSV Antibody ELISA (ThermoFisher, USA), using serum samples obtained from 5 conventional PRRSV-positive and 5 PRRSV-negative Polish pig farms. Specificity of ELISAs ranged from 94.2% (ThermoFisher) to 100% (IDEXX and Hipra). ThermoFisher ELISA had the highest detection rate and detected 67.2% samples from PRRSV-positive farms as positive but considering its low specificity some of the positive results may be incorrect. IDEXX ELISA considered as a reference detected 64.8% positive sera in PRRSV-positive farms. On the other hand Hipra Elisa identified only 51.8% of samples as positive. The diagnostic sensitivity of five ELISAs relative to IDEXX ranged from 80.3% (Hipra) to 96.3% (ThermoFisher). Our study showed significant differences in specificity and diagnostic sensitivity between the compared kits. The differences in the performance appeared to be practically negligible on farms where early infection with PRRSV occurred. However, on PRRSV-negative farms, or farms with PRRSV stable sow herds, some ELISAs can give results not reflecting the infection status in specific age groups.