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

PRRSv neutralizing antibodies provide in vivo cross-protection to PRRSv1 and PRRSv2 challenge

Virus Res. 2018 Feb 3. pii: S0168-1702(17)30933-4. doi: 10.1016/j.virusres.2018.01.015. [Epub ahead of print]

Porcine reproductive and respiratory syndrome virus neutralizing antibodies provide in vivo cross-protection to PRRSV1 and PRRSV2 viral challenge.

Robinson SR1, Rahe MC1, Gray DK1, Martins KV1, Murtaugh MP2.

Author information

1

Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN, USA.

2

Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN, USA. Electronic address: murta001@umn.edu.

Abstract

Vaccine control and prevention of porcine reproductive and respiratory syndrome (PRRS), the most important disease of swine, is difficult to achieve. However, the discovery of broadly neutralizing antibody activity against porcine reproductive and respiratory syndrome virus (PRRSV) under typical field conditions opens the door to new immunologic approaches for robust protection. We show here that passive administration of purified immunoglobulins with neutralizing antibodies reduced PRRSV2 infection by up to 96%, and PRRSV1 infection by up to 87%, whereas immune immunoglobulins lacking neutralizing activity had no effect on viral infection. Hence, immune competence of passive immunoglobulin transfer was associated specifically with antibody neutralizing activity. Current models of PRRSV infection implicate a minor envelope glycoprotein (GP) complex including GP2, GP3, and GP4, as critical to permissive cell infection. However, conserved peptides comprising the putative cell attachment structure did not attenuate neutralization or viral infection. The results show that immunological approaches aimed at induction of broadly neutralizing antibodies may substantially enhance immune protection against PRRSV. The findings further show that naturally occurring viral isolates are able to induce protective humoral immunity against unrelated PRRSV challenge, thus removing a major conceptual barrier to vaccine development.

KEYWORDS: 

Cross-protection; Neutralizing antibodies; Neutralizing epitope; PRRSV; Passive transfer; Swine

PMID:

 

29408442

 

DOI:

 

10.1016/j.virusres.2018.01.015