Proteomic analysis of rainbow trout (Oncorhynchus mykiss, Walbaum) serum after administration of probiotics in diets Jason Brunt, Rasmus Hansen, Derek J. Jamieson, Brian Austin * School of Life Sciences, John Muir Building, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, Scotland, UK Received 4 May 2007; received in revised form 17 July 2007; accepted 26 September 2007 Abstract The response of rainbow trout (Oncorhynchus mykiss, Walbaum) towards probiotics present in the feed was investigated by examining the proteome of serum as a measure of the acute phase response (APR). Proteomic analysis by two-dimensional electrophoresis (2D) concurrently with mass spectrometry was used to detect APR related proteins in rainbow trout serum following feeding with probiotics Aeromonas sobria GC2 and Bacillus sp. JB-1. Three candidate proteins increased following use of GC2, and were putatively identified as NADH dehydrogenase, dystrophin and mKIAA0350. Conversely, one of the proteins, which were induced following use of JB-1 was identified as transferrin. # 2007 Elsevier B.V. All rights reserved. Keywords: Probiotic; Fish disease; Acute phase response; Innate immunity; Proteomics 1. Introduction There is concern over the use of antimicrobial compounds in aquaculture, and the increased emer- gence of antibiotic-resistance bacteria (Balca ´zar et al., 2006). Alternative strategies include the use of probiotic bacteria (Vine et al., 2006). To date, there has been a diverse range of organisms considered for use as probiotics (Irianto and Austin, 2002). Possible modes of action include inhibition of pathogenic bacteria by preventing their colonisation in the host (=competitive exclusion), the production of antimicrobial compounds, competition for nutrients chemicals and available energy, and stimulation or enhancement of the immune response (Gomez-Gil et al., 2000; Balca ´zar et al., 2006; Ringø and Gatesoupe, 1998; Vine et al., 2006; Sakata, 1990; Verschuere et al., 2000; Hong et al., 2005; Irianto and Austin, 2002, 2003). The acute phase response (APR) has been defined as a rapid, orchestrated, physiologically induced response to tissue injury, infection, neoplasia, trauma and stress (Baumann and Gauldie, 1994; Jensen et al., 1997). This involves a large number of acute phase proteins (APP) and functions in a variety of defense-related activities, such as limiting the dispersal of infectious agents, repairing of tissue damage, the killing of micro- organisms and restoration of a healthy state (Larsen et al., 2001; Gerwick et al., 2000, 2002). Several of the mammalian positive APP has been identified, but it is anticipated that more are still unknown because the host response is complex, and has received only marginal attention. The proteins that have been identified include fibrinogen, C-reactive protein (CRP), a-2 macroglobu- lin, serum amyloid A (SAA), serum amyloid P (SAP) and mannose-binding protein A (also known as mannose binding lectin) (Sastry et al., 1991). In response to appropriate inflammatory stimuli, many www.elsevier.com/locate/vetimm Available online at www.sciencedirect.com Veterinary Immunology and Immunopathology 121 (2008) 199–205 * Corresponding author. Tel.: +44 131 451 3452; fax: +44 131 451 3009. E-mail address: b.austin@hw.ac.uk (B. Austin). 0165-2427/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.vetimm.2007.09.010