Development and efficacy of Streptococcus iniae live-attenuated vaccines in Nile tilapia, Oreochromis niloticus.

Autor: Heckman TI; Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA., Shahin K; Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA; Aquatic Animals Diseases Laboratory, Aquaculture Division, National Institute of Oceanography and Fisheries, P.O. Box 43511, Suez, Egypt., Henderson EE; California Animal Health and Food Safety Lab, School of Veterinary Medicine, University of California, Davis, CA, 92408, USA., Griffin MJ; Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Stoneville, MS, 39762, USA., Soto E; Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA. Electronic address: sotomartinez@ucdavis.edu.
Jazyk: angličtina
Zdroj: Fish & shellfish immunology [Fish Shellfish Immunol] 2022 Feb; Vol. 121, pp. 152-162. Date of Electronic Publication: 2021 Dec 26.
DOI: 10.1016/j.fsi.2021.12.043
Abstrakt: Streptococcus iniae is a re-emerging bacterial pathogen in freshwater and marine aquaculture worldwide. There are no commercial vaccines available for S. iniae in the United States, and autogenous vaccines are restricted to inactivated whole-cell preparations with limited protection against heterogenous strains. Live-attenuated vaccines (LAV) represent an advantageous alternative to these bacterins, as they induce robust cellular and humoral immunity, and may provide longer lasting protection through less stressful routes of administration. We investigated whether accumulation of mutations in S. iniae by serial passage in the presence of rifampin can generate immunogenic LAV conferring protection against challenge with heterologous wild-type (WT) S. iniae strains in Nile tilapia (Oreochromis niloticus). Three lineages of rifampin-resistant S. iniae strains were generated from three genetically distinct parent strains (n = 9) by multiple passages in increments of Rifamycin SV sodium salt. Growth in liquid media, extent of capsulation, antimicrobial susceptibility, survival in Nile tilapia whole blood, and cytotoxicity in an O. mossambicus endothelial cell line were compared between the passaged and WT strains. Nile tilapia challenges were used to assess strain virulence, generation of anti-S. iniae IgM, and the protection conferred by LAV candidates against virulent S. iniae. Rifampin-resistant strains demonstrated changes in growth rate and cytotoxicity in endothelial cells, as well as significant reductions in whole blood survival (p < 0.05). Selected strains also showed attenuated virulence in the Nile tilapia challenge model, and anti-S. iniae IgM generated against these strains demonstrated cross-reactivity against heterologous bacteria. Immunization by intracoelomic injection induced protection against a virulent WT strain of S. iniae, with relative percent survival up to 95.05%.
(Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)
Databáze: MEDLINE
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