Submitted to: European Association of Fish Pathologists
Publication Type: Other
Publication Acceptance Date: June 11, 1999
Publication Date: September 19, 1999
Citation: Klesius, P.H., Shoemaker, C.A., Evans, J.J. Streptococcus iniae vaccine for prevention of Streptococcus disease in Tilapia. Eurpoean association of fish pathologists. Ninth International Conference "Disease of Fish and Shellfish". Poster. 1999. Technical Abstract: We evaluated the effectiveness of Streptococcus iniae vaccines prepared from formalin-killed cells and concentrated extracellular products (greater than 2 kDa) using each of 3 isolates of S. iniae (ARS-10, ARS-47 and ARS-60) in 3 sizes of tilapia, Oreochromis niloticus, for prevention of streptococcus disease. Two routes of injection, intraperitoneal (IP) and intramuscular (IM) injection were evaluated for vaccine efficacy. Tilapia were vaccinated by IP or IM injection of the vaccine or tryptic soy broth (control) and challenged by IP injection with 1 X 108 colony-forming units of S. iniae after 26-35 days post immunization. In the first trial, we evaluated the effectiveness of the ARS-10 vaccine by IP administration and challenged with ARS-10 in tilapia with mean weights of 25 and 100 g. The resulting relative percent survivals (RPS) were 95.3 and 89.5 %, respectively. In the second trial, the RPS was 100 % in 30 g tilapia by immunization with ARS-47 vaccine and challenged with the same isolate (ARS-47 S. iniae). In the third trial, we found that the RPS was 93.4 % in 18 g tilapia IP immunized with the ARS-10 vaccine and challenged with another isolate, ARS-60 S. iniae. In all studies, the IP vaccinated groups did not exhibit any signs of streptococcus disease characterized by erratic swimming, hemorrhagic exopthalmia and ocular opacity. We also evaluated the effectiveness of IM immunization using the ARS-10 vaccine and challenged with ARS-60 S. iniae in 18 g tilapia. The resulting RPS was 57.8 %. Signs of streptococcus disease were evident in some of the IM vaccinates. Administration of the vaccine by IM injection was marginally protective in preventing streptococcus disease. However, IP vaccination was effective in preventing streptococcus disease in all sizes of tilapia used when challenged with homologous and heterologous S. iniae isolates.