The immune response of tilapia Oreochromis mossambicus and its susceptibility to Streptococcus iniae under stress in low and high temperatures.
Mozambique tilapia Oreochromis mossambicus acclimated to 27 degrees C were then held at 19, 23, 27 (control), 31 and 35 degrees C, and were examined for non-specific cellular and humoral responses after 12-96 h. Total leucocyte count decreased significantly when fish were transferred to 19 and 23 degrees C after 48 and 96 h, and when transferred to 35 degrees C over 12-96 h, respectively. Respiratory burst decreased significantly when fish were transferred to 19, 31 and 35 degrees C over 24-96 h, whereas phagocytic activity and phagocytic index decreased significantly when fish were transferred to low temperatures (19 and 23 degrees C) and high temperatures (31 and 35 degrees C) over 12-96 h. Lysozyme activity decreased significantly when fish were transferred to 19 degrees C after 12-96 h, but increased significantly when transferred to 31 and 35 degrees C over 48-96 h. Alternative complement pathway (ACH(50)) also decreased significantly when transferred to 19 and 23 degrees C after 12h, but increased significantly when transferred to 31 and 35 degrees C after 24h. In another experiment, tilapia reared at 27 degrees C were injected intraperitoneally with Streptococcus iniae at a dose of 1 x 10(7)colony-forming units (cfu)fish(-1), and then reared onward at water temperatures of 19, 23, 27 (control), 31 and 35 degrees C. Over 48-168 h, the cumulative mortality of S. iniae-injected fish held in 19 and 35 degrees C was significantly higher than that of injected-fish held in 23, 27 and 31 degrees C. It is concluded that transfer of tilapia O. mossambicus from 27 degrees C to low temperatures (19 and 23 degrees C) after 12h, and transfer of fish from 27 degrees C to high temperatures (31 and 35 degrees C) reduced their immune capability. Moreover, tilapia under temperature stress at 19 and 35 degrees C from 27 degrees C decreased its resistance against S. iniae.
Ndong
Diegane
D
Department of Aquaculture, College of Life Sciences, National Taiwan Ocean University, Keelung, Taiwan 202, ROC.
Chen
Yu-Yuan
YY
Lin
Yu-Hung
YH
Vaseeharan
Baskaralingam
B
Chen
Jiann-Chu
JC
D000818:Animals; D004198:Disease Susceptibility / Q000662:veterinary*; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology; D007958:Leukocyte Count; D007962:Leukocytes / Q000276:immunology; D009113:Muramidase / Q000032:analysis / Q000378:metabolism; D010587:Phagocytosis / Q000276:immunology; D016897:Respiratory Burst / Q000276:immunology; D013290:Streptococcal Infections / Q000276:immunology / Q000662:veterinary*; D013291:Streptococcus / Q000276:immunology*; D013312:Stress, Physiological / Q000662:veterinary*; D013696:Temperature; D017210:Tilapia / Q000276:immunology*; D013997:Time Factors
D009113:Muramidase