PRRSv-specific IgM-IgA in oral fluids reveals infection in the presence of maternal antibody

Vet Microbiol. 2018 Feb;214:13-20. doi: 10.1016/j.vetmic.2017.11.011. Epub 2017 Nov 17.

Detection of porcine reproductive and respiratory syndrome virus (PRRSV)-specific IgM-IgA in oral fluid samples reveals PRRSV infection in the presence of maternal antibody.

Rotolo ML1, Giménez-Lirola L2, Ji J3, Magtoto R2, Henao-Díaz YA2, Wang C4, Baum DH2, Harmon KM2, Main RG2, Zimmerman JJ2.

Author information

1

Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, USA. Electronic address: mrotolo@iastate.edu.

2

Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.

3

Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, IA, USA.

4

Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, USA; Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, IA, USA.

Abstract

The ontogeny of PRRSV antibody in oral fluids has been described using isotype-specific ELISAs. Mirroring the serum response, IgM appears in oral fluid by 7days post inoculation (DPI), IgA after 7 DPI, and IgG by 9 to 10 DPI. Commercial PRRSV ELISAs target the detection of IgG because the higher concentration of IgG relative to other isotypes provides the best diagnostic discrimination. Oral fluids are increasingly used for PRRSV surveillance in commercial herds, but in younger pigs, a positive ELISA result may be due either to maternal antibody or to antibody produced by the pigs in response to infection. To address this issue, a combined IgM-IgA PRRSV oral fluid ELISA was developed and evaluated for its capacity to detect pig-derived PRRSV antibody in the presence of maternal antibody. Two longitudinal studies were conducted. In Study 1 (modified-live PRRS vaccinated pigs), testing of individual pig oral fluid samples by isotype-specific ELISAs demonstrated that the combined IgM-IgA PRRSV ELISA provided better discrimination than individual IgM or IgA ELISAs. In Study 2 (field data), testing of pen-based oral fluid samples confirmed the findings in Study 1 and established that the IgM-IgA ELISA was able to detect antibody produced by pigs in response to wild-type PRRSV infection, despite the presence of maternal IgG. Overall, the combined PRRSV IgM-IgA oral fluid ELISA described in this study is a potential tool for PRRSV surveillance, particularly in populations of growing pigs originating from PRRSV-positive or vaccinated breeding herds.

KEYWORDS: 

ELISA; IgM-IgA; Oral fluid; PRRSV; Surveillance

PMID:

 

29408024

 

DOI:

 

10.1016/j.vetmic.2017.11.011