Subcellular components of probiotics Kocuria SM1 and Rhodococcus SM2 induce protective immunity in rainbow trout (Oncorhynchus mykiss, Walbaum) against Vibrio anguillarum

Citation

Sharifuzzaman SM, Abbass AA, Tinsley JW & Austin B (2011) Subcellular components of probiotics Kocuria SM1 and Rhodococcus SM2 induce protective immunity in rainbow trout (Oncorhynchus mykiss, Walbaum) against Vibrio anguillarum. Fish and Shellfish Immunology, 30 (1), pp. 347-353. http://www.sciencedirect.com/science/journal/10504648; https://doi.org/10.1016/j.fsi.2010.11.005

Abstract
The efficacy of cellular components of probiotics Kocuria SM1 and Rhodococcus SM2 to protect rainbow trout (Oncorhynchus mykiss, Walbaum) against vibriosis was assessed. Groups of fish (average weight = 10–15 g) were immunized intraperitoneally (i.p.) with 0.1 ml of subcellular materials, i.e. 0.2 ± 0.05 mg protein per fish, comprising extracellular proteins (ECPs), cell wall proteins (CWPs) and whole cell proteins (WCPs) of SM1 and SM2, respectively, or with 0.1 ml of phosphate-buffered saline (PBS) to serve as the control. Seven days after administration, fish from each group were challenged i.p. with 0.1 ml of a suspension in PBS of 3 × 105 cells ml−1 per fish of Vibrio anguillarum. Use of CWPs and WCPs demonstrated significantly (P < 0.05) better protection against V. anguillarum insofar as mortalities were reduced to 11–17% [relative percent survival (RPS) = 80–87%], although ECPs fared less well (mortalities = 33–38%; RPS = 56–62%; P > 0.05), compared to 86% mortalities of the controls. The mode of action reflected activation of innate immune factors by CWPs and WCPs, demonstrating significantly (P < 0.05) increased expression of respiratory burst (optical density; OD550nm) from 0.039 to 0.043–0.045, peroxidase (OD550nm) from 0.26 to 0.37–0.55, and bacterial killing activities (i.e. percentage of surviving bacteria reduced from 79% to 56–57% for SM2). Moreover, an elevation of leucocyte number (from 1.93% to 1.98–2.93%; P > 0.05) and immunoglubolin level (from 27 mg ml−1 to 28.5–33 mg ml−1; P > 0.05) were observed with the experimental groups. These results indicate that cell components of the probiotics stimulate an immune response.

Keywords
Probiotic; fish pathogens; Rainbow trout; Aquaculture

Journal
Fish and Shellfish Immunology: Volume 30, Issue 1