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United States Department of Agriculture

Agricultural Research Service

Title: Streptococcus Agalactiae Vaccination and Infection Stress in Nile Tilapia, Oreochromis Niloticus

Authors
item Evans, Joyce
item Klesius, Phillip
item Shoemaker, Craig
item Fitzpatrick, Brendan

Submitted to: Journal of Applied Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 5, 2003
Publication Date: November 1, 2004
Citation: EVANS, J.J., KLESIUS, P.H., SHOEMAKER, C.A., FITZPATRICK, B.T. STREPTOCOCCUS AGALACTIAE VACCINATION AND INFECTION STRESS IN NILE TILAPIA, OREOCHROMIS NILOTICUS. JOURNAL OF APPLIED AQUACULTURE. 2004. vol 16 numbers 3/4:105-115.

Interpretive Summary: Associations between vaccination and the stress response in fish have not been adequately investigated despite knowledge of the largely negative effects of stress on the immune system. Stress has become a major concern in aquaculture and fisheries management due to its potential deleterious effects on fish metabolism, growth and disease resistance. Intraperitoneal (IP) vaccination of fish with killed vaccines are often perceived as labor intensive and stressful to the fish. However, the physiological measurement of the degree of stress experienced (stress response) from the IP vaccination process (stressor) and subsequent susceptibility to infection (infection stress) has received little attention. Recently, we developed a modified bacterin vaccine against group B Streptococcus agalactiae isolated from a fish epizootic. The objective of this study was to develop preliminary information on the association between S. agalactiae vaccination, stress and subsequent S. agalactiae infection using this newly developed non adjuvant vaccine in tilapia. Increased blood glucose levels were used to evaluate stress in fish at different time intervals following vaccination and challenge with S. agalactiae. Significant increases in blood glucose levels were observed only in association with the injection of the vaccine and at 2h after injection. After S. agalactiae challenge, both controls and vaccinates had significantly higher blood glucose values at 2, 24, 48, and 72 h than at 0 h. However, blood glucose levels in vaccinates were significantly lower than the controls at 24, 48 and 312 h. Blood glucose levels and mortality of the infected controls were significantly correlated (r2=0.9236, P = 0.0134). The cumulative mortality of the vaccines and controls was 10 and 60% after 13 d post challenge, respectively. The relative percent survival (RPS) of 83.4 indicated that the vaccine was efficacious and it had induced short-term stress in tilapia. These preliminary results also suggested, for the first time, that vaccination may significantly reduce the infection stress associated with S. agalactiae infection in tilapia.

Technical Abstract: The stress response following intraperitoneal (IP) injection of a non-adjuvant Streptococcus agalactiae vaccine in cultured warmwater Nile tilapia (Oreochromis niloticus) has not been investigated. Further, little or no information is available on stress following S. agalactiae infection and what effect, if any, vaccination has on susceptibility to infection. The objective of this study was to develop preliminary information on the associations between vaccination, stress, and infection. Blood glucose levels were used to evaluate stress in the fish at different time intervals following vaccination and challenge with S. agalactiae. Blood glucose levels were measured in vaccinates and controls at 0, 2, 6, 24 h, and 28 d post-immunization (0 h pre-challenge), and at 2, 6, 24, 48, 72, and 312 h following challenge with 1.5 ' 104 colony forming units (CFU) of S. agalactiae /fish. Significant increases in blood glucose levels were observed only in association with the injection of the vaccine and at 2 h after injection. After S. agalactiae challenge, both controls and vaccinates had significantly higher blood glucose values at 2, 24, 48, and 72 h than at 0 h. However, blood glucose levels in vaccinates were significantly lower than the controls at 24, 48, and 312 h. Blood glucose levels and mortality of the infected controls were significantly correlated (r2=0.9236, P = 0.0134). The cumulative mortality of the vaccines and controls was 10 % and 60% after 13 d post challenge, respectively. The relative percent survival (RPS) was 83.4. Our results indicate that the vaccine was efficacious against S. agalactiae and induced short-term stress in tilapia. These preliminary results also suggested, for the first time, that vaccination may significantly reduce the infection stress associated with S. agalactiae infection in tilapia.

Last Modified: 10/20/2014
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