Pellet feed adsorbed with the recombinant Lactococcus lactis BFE920 expressing SiMA antigen induced strong recall vaccine effects against Streptococcus iniae infection in olive flounder (Paralichthys olivaceus).
The aim of this study was to develop a fish feed vaccine that provides effective disease prevention and convenient application. A lactic acid bacterium (LAB), Lactococcus lactis BFE920, was modified to express the SiMA antigen, a membrane protein of Streptococcus iniae. The antigen was engineered to be expressed under the nisin promoter, which is induced by nisin produced naturally by the host LAB. Various sizes (40 ± 3.5 g, 80 ± 2.1 g, and 221 ± 2.4 g) of olive flounder (Paralichthys olivaceus) were vaccinated by feeding the extruded pellet feed, onto which the SiMA-expressing L. lactis BFE920 (1.0 × 10(7) CFU/g) was adsorbed. Vaccine-treated feed was administered twice a day for 1 week, and priming and boosting were performed with a 1-week interval in between. The vaccinated fish had significantly elevated levels of antigen-specific serum antibodies and T cell marker mRNAs: CD4-1, CD4-2, and CD8a. In addition, the feed vaccine significantly induced T cell effector functions, such as the production of IFN-γ and activation of the transcription factor that induces its expression, T-bet. When the flounder were challenged by intraperitoneal infection and bath immersion with S. iniae, the vaccinated fish showed 84% and 82% relative percent survival (RPS), respectively. Furthermore, similar protective effects were confirmed even 3 months after vaccination in a field study (n = 4800), indicating that this feed vaccine elicited prolonged duration of immunopotency. In addition, the vaccinated flounder gained 21% more weight and required 16% less feed to gain a unit of body weight compared to the control group. The data clearly demonstrate that the L. lactis BFE920-SiMA feed vaccine has strong protective effects, induces prolonged vaccine efficacy, and has probiotic effects. In addition, this LAB-based fish feed vaccine can be easily used to target many different pathogens of diverse fish species.
School of Life Science, Handong University, Pohang 791-708, Republic of Korea.
Daniel
D
Kim
School of Life Science, Handong University, Pohang 791-708, Republic of Korea.
Bo Ram
BR
Beck
Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Republic of Korea.
Sun Min
SM
Lee
New Business Development Dept., Medytox Inc, Republic of Korea.
Jongsu
J
Jeon
Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea.
Dong Wook
DW
Lee
GyeongSangbuk-Do Fisheries Technology Center, Pohang 791-941, Republic of Korea.
Jae Il
JI
Lee
School of Life Science, Handong University, Pohang 791-708, Republic of Korea. Electronic address: sksong@handong.edu.
Seong Kyu
SK
Song
D000821:Animal Feed / Q000032:analysis; D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics / Q000276:immunology; D004032:Diet / Q000662:veterinary; D005393:Fish Diseases / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D005412:Flatfishes; D013294:Lactococcus lactis / Q000235:genetics / Q000276:immunology; D009077:Mucins / Q000235:genetics / Q000276:immunology; D009561:Nisin / Q000235:genetics; D030781:Organisms, Genetically Modified; D019936:Probiotics; D011401:Promoter Regions, Genetic; D013290:Streptococcal Infections / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D022541:Streptococcal Vaccines / Q000235:genetics / Q000276:immunology*; D000070058:Streptococcus iniae / Q000276:immunology
D000951:Antigens, Neoplasm; D009077:Mucins; D022541:Streptococcal Vaccines; C042384:gastro-intestinal mucus-associated antigens; D009561:Nisin; C102526:nisin A
Feed vaccine; Lactococcus lactis BFE920; Olive flounder; Oral immunization; Streptococcosis; Streptococcus iniae; Vaccine vehicle