Journal of Virological Methods 197 (2014) 63–66 Contents lists available at ScienceDirect Journal of Virological Methods jou rn al hom ep age: www.elsevier.com/locate/jviromet Comparison of commercial enzyme-linked immunosorbent assays and fluorescent microbead immunoassays for detection of antibodies against porcine reproductive and respiratory syndrome virus in boars Priscilla F. Gerber a,b , Luis G. Giménez-Lirola a , Patrick G. Halbur a , Lei Zhou c , Xiang-Jin Meng c , Tanja Opriessnig a,d,∗ a Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA, USA b Laboratório de Pesquisa em Virologia Animal, Departamento de Medicina Veterinária Preventiva, Universidade Federal de Minas Gerais, Minas Gerais, Brazil c Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA d The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian EH25 9RG, United Kingdom Article history: Received 21 July 2013 Received in revised form 30 October 2013 Accepted 9 December 2013 Available online 19 December 2013 Keywords: PRRSV Serology Diagnosis Oral fluid Pigs a b s t r a c t The objective of this study was to compare the ability of two commercial enzyme-linked immunosorbent assays (ELISAs) and an in-house fluorescent microbead immunoassay (FMIA) to detect IgG antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) types 1 and 2 in serum and oral fluids from boars infected experimentally. Samples from uninfected control pigs and PRRSV-negative field samples were also used. Serum samples were tested by ELISAs (IDEXX Se, HIPRA Se) and an in-house FMIA-Se for detection of PRRSV types 1 and 2. Oral fluids were tested by ELISAs (IDEXX-SO, IDEXX-OF, HIPRA-OF) for detection of PRRSV types 1 and 2. Among the sera, IDEXX-Se and HIPRA-Se had similar sensitivity and specificity (p > 0.05); however, IDEXX-Se detected positive animals earlier than HIPRA- Se (p < 0.05). FMIA-Se had the highest false-positive rates in known negative field samples (1/205 for IDEXX-Se, 5/205 for HIPRA-Se, and 37/205 for FMIA-Se; p < 0.01). Serum and oral fluid samples had similar detection rates and antibody kinetics using the IDEXX tests. There was a higher detection rate in serum than oral fluid using the HIPRA assays. In this study, the nucleocapsid protein utilized as antigen in the FMIAs yielded a low specificity. IDEXX-Se had the earliest detection and similar sensitivity and specificity to the HIPRA-Se. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Porcine reproductive and respiratory syndrome virus (PRRSV) affects pigs worldwide. This enveloped, single-stranded, positive- sense RNA virus of the family Arteriviridae can be divided into two genotypes: type 1 (European type [EU]) and type 2 (North Ameri- can type [NA]) (Meng et al., 1995). As a part of control programs, most boar studs in the United States are PRRSV-negative and are monitored closely for evidence of virus infection to minimize the spread of the virus and its associated economic losses (Corzo et al., 2010). Successful disease control programs are based on accurate, cost-effective, and timely detection of infected animals and herds. ∗ Corresponding author at: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1600 S. 16th Street, Ames, IA 50011, USA. Tel.: +1 5152941137; fax: +1 5152943564. E-mail address: tanjaopr@iastate.edu (T. Opriessnig). Recently, increased rates of false-negative results were reported in several PRRSV reverse transcription polymerase chain reac- tion assays used commonly in veterinary diagnostic laboratories, and combined use of different assays has been recommended to improve the diagnosis for PRRSV in early stages of infection (Harmon et al., 2012; Toplak et al., 2012; Wernike et al., 2012; Gerber et al., 2013). ELISA is the method that is used most commonly for detection of antibodies against PRRSV (Okinaga et al., 2009) due to its speci- ficity, cost-effectiveness, and simplicity. More recently, the use of fluorescent microbead-based immunoassays (FMIA) based on the PRRSV nucleocapsid (N) protein as the antigen have been success- ful for detection of anti-PRRSV antibodies in serum and oral fluid samples (Lin et al., 2011; Langenhorst et al., 2012). An advantage of this technology is that FMIA allows screening of antibodies to mul- tiple pathogens or antigens simultaneously in one reaction well. Therefore it reduces the time and labor required for assay perfor- mance and also requires a smaller amount of sample and coating antigen thereby further reducing cost. Although serum samples are 0166-0934/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jviromet.2013.12.001