Detection of antibodies in Atlantic salmon using a bead-based multiplexed immunoassay

• Main Author: Teige, Lena Hammerlund
• Other Authors: Boysen, Preben, Dahle, Maria K., Storset, Anne
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Norwegian University of Life Sciences, Ås 2020
• Subjects: Atlantic salmon; Piscine orthoreovirus; Salmonid alphavirus; IgM; Immunoassay; Antibody; Norway; Sav’
• Online Access: https://hdl.handle.net/11250/3053470

Viral diseases are among of the main challenges in aquaculture in Norway today. Heart- and skeletal muscle inflammation, caused by Piscine orthoreovirus (PRV), and pancreas disease (PD), caused by Salmonid alphavirus (SAV), both cause huge losses of farmed Atlantic salmon. Vaccination is a possible solution that is already contributing to the control of bacterial diseases. Unfortunately, making effective vaccines against viral diseases has been challenging and information about which immune mechanisms that are involved in protection is lacking. Antibodies can mediate complete protection against some diseases, and antibody levels after vaccination can correlate with protection, even if the protection is mediated by other mechanisms. In addition, antibody detection can be used in disease surveillance to determine if a fish population is or has been infected with a virus. Unfortunately, measuring antibody levels in salmon is not straightforward. Such measurements have not been widely used, and often show high levels of background binding. An important reason for this is that fish antibodies are of the IgM type. IgM is less specific than IgG, the dominating antibody in mammals. Therefore, other methods, like PCR and histology, are more used in diagnostics in Atlantic salmon. In this work, we have for the first time used an assay based on microscopic magnetic beads conjugated with antigen to measure antibody levels in Atlantic salmon. This method has a high sensitivity and can be used to measure antibodies against several proteins simultaneously in the same sample. By using this method, we have detected antibodies against PRV and SAV. In paper I and II, plasma from two PRV challenge trials was used to detect antibodies against the PRV proteins μ1c, μNS and σ1. We also detected antibodies against PRV1- σ1 in plasma from PRV-3-infected rainbow trout. There have been no previous publications detecting antibodies against PRV. The peak antibody level coincided with decreased pathology in the heart. In addition to showing ...