title: Subcellular components of probiotics Kocuria SM1 and Rhodococcus SM2 induce protective immunity in rainbow trout (Oncorhynchus mykiss, Walbaum) against Vibrio anguillarum.
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 × 10(5) 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; OD(550 nm)) from 0.039 to 0.043-0.045, peroxidase (OD(550 nm)) 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.
authors.affiliation: School of Life Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK, Scotland, UK.
authors.forename: S M
authors.initials: SM
authors.lastname: Sharifuzzaman
authors.forename: A
authors.initials: A
authors.lastname: Abbass
authors.forename: J W
authors.initials: JW
authors.lastname: Tinsley
authors.forename: B
authors.initials: B
authors.lastname: Austin
mesh_terms: D000818:Animals; D005393:Fish Diseases / Q000382:microbiology / Q000517:prevention & control*; D017686:Oncorhynchus mykiss; D019936:Probiotics / Q000494:pharmacology*; D016897:Respiratory Burst; D012240:Rhodococcus / Q000166:cytology*; D013347:Subcellular Fractions; D014733:Vibrio / Q000145:classification*; D014735:Vibrio Infections / Q000517:prevention & control / Q000662:veterinary*