title: Evaluation of Streptococcus iniae killed bacterin and live attenuated vaccines in hybrid striped bass through injection and bath immersion.
abstract: Streptococcus iniae poses a serious threat to finfish aquaculture operations worldwide. Stringent regulatory standards limit the use of antibiotics to treat S. iniae infections; improved vaccination strategies are thus of great interest. We investigated the potential for efficient, non-injectable batch vaccination via the use of live attenuated vaccines. Three attenuated S. iniae strains with genetic mutations eliminating the production of virulence factors--capsular polysaccharide (delta cpsD), M-like protein (delta simA), and phosphoglucomutase (delta pgmA)--were evaluated in parallel with an adjuvanted, formalin-killed, whole-cell S. iniae bacterin. Juvenile hybrid striped bass (HSB; Morone chrysops x M. saxatilis) were vaccinated through intraperitoneal (i.p.) injection or bath immersion and held for 800 degree-days prior to challenge with a lethal dose of the virulent wild-type (WT) S. iniae parent strain. The delta cpsD, delta pgmA, and bacterin vaccines provided the highest level of vaccination safety (0% mortality), whereas the delta simA mutant, although it caused 12 to 16% vaccination-related mortality, was the only vaccine candidate to provide 100% protection in both i.p. and immersion delivery models. Our studies demonstrate the efficacy of live attenuated vaccines for prevention of S. iniae infection, and identify immersion delivery of live vaccines as an attractive option for use in commercial aquaculture settings.
authors.affiliation: Department of Pediatrics, Division of Pharmacology and Drug Discovery, University of California, San Diego, 9500 Gilman Drive, MC 0687, La Jolla, California 92093-0687, USA.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Locke
authors.forename: Mike R
authors.initials: MR
authors.lastname: Vicknair
authors.forename: Vaughn E
authors.initials: VE
authors.lastname: Ostland
authors.forename: Victor
authors.initials: V
authors.lastname: Nizet
authors.forename: John T
authors.initials: JT
authors.lastname: Buchanan
mesh_terms: D000287:Administration, Topical; D000818:Animals; D001492:Bass; D007274:Injections, Intraperitoneal; D013290:Streptococcal Infections / Q000517:prevention & control / Q000662:veterinary*; D022541:Streptococcal Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D013291:Streptococcus / Q000276:immunology*; D013997:Time Factors; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology
chemical_list: D022541:Streptococcal Vaccines; D014613:Vaccines, Attenuated