Comparison of different commercial ELISAs for detection of antibodies against porcine respiratory and reproductive syndrome virus in serum

Abstract

BackgroundIn recent years, several new ELISAs for the detection of antibodies against the porcine reproductive and respiratory disease virus (PRRSV) in pig serum have been developed. To interpret the results, specificity and sensitivity data as well as agreement to a reference ELISA must be available. In this study, three commercial ELISAs (INgezim PRRS 2.0 - ELISA II, Priocheck® PRRSV Ab porcine – ELISA III and CIVTEST suis PRRS E/S PLUS - ELISA IV, detecting PRRSV type 1 antibodies) were compared to a standard ELISA (IDEXX PRRS X3 Ab Test - ELISA I). The serum of three pigs vaccinated with an attenuated PRRSV live vaccine (genotype 2) was tested prior to and several times after the vaccination. Furthermore, serum samples of 245 pigs of PRRSV positive herds, 309 pigs of monitored PRRSV negative herds, 256 fatteners of assumed PRRSV negative herds with unknown herd history and 92 wild boars were tested with all four ELISAs.ResultsELISAs II and III were able to detect seroconversion of vaccinated pigs with a similar reliability. According to kappa coefficient, the results showed an almost perfect agreement between ELISA I as reference and ELISA II and III (kappa > 0.8), and substantial agreement between ELISA I and ELISA IV (kappa = 0.71). Sensitivity of ELISA II, III and IV was 96.0%, 100% and 91.5%, respectively. The specificity of the ELISAs determined in samples of monitored PRRSV negative herds was 99.0%, 95.1% and 96.4%, respectively. In assumed negative farms that were not continually monitored, more positive samples were found with ELISA II to IV. The reference ELISA I had a specificity of 100% in this study.ConclusionsAll tested ELISAs were able to detect a PRRSV positive herd. The specificity and sensitivity of the tested commercial ELISAs, however, differed. ELISA II had the highest specificity and ELISA III had the highest sensitivity in comparison to the reference ELISA. ELISA IV had a lower sensitivity and specificity than the other ELISAs.

Ability of ELISAs to detect antibodies against porcine respiratory and reproductive syndrome virus in serum of pigs after inactivated vaccination and subsequent challenge

“…The nucleocapsid-based IDEXX PRRS X3 Ab test is usually used as the gold standard for detection of PRRSV Ab by ELISA [1–4]. In our study, with this ELISA, however, no Ab could be detected in serum samples of piglets vaccinated with an inactivated vaccine.…”

“…One positive result was found with the INgezim ELISA in the non-vaccinated group at day 0. The specificity of this ELISA was calculated with 99% in another study, which is slightly lower than the specificity of the IDEXX ELISA [1]. This can be the explanation for the false positive result.…”

“…Data are published about the performance, sensitivity and specificity of the ELISAs tested in this study [1, 6, 15, 16]. They did, however, not concern serum of pigs vaccinated with an inactivated vaccine.…”

“…All serum samples were tested on each sampling point with a commercial reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) assay (TaqMan® NA and EU PRRSV Reagents and Controls, ThermoFisher Scientific, Vienna, Austria) for the presence of PRRSV RNA as described previously [1]. …”

“…In studies validating or comparing new enzyme-linked immunosorbent assays (ELISA) for the detection of antibodies (Ab) against the porcine reproductive and respiratory syndrome virus (PRRSV), the IDEXX PRRS X3 Ab test (IDEXX, Westbrook, USA) is usually used as the gold standard [1–4]. This ELISA system has a sensitivity of 98.8% and a specificity of 99.9%, according to manufacturer.…”