Antigens of the type-three secretion system of Aeromonas salmonicida subsp. salmonicida prevent protective immunity in rainbow trout

Bergh, Philippe Vanden; Burr, Sarah E; Benedicenti, Ottavia; von Siebenthal, Beat; Frey, Joachim; Wahli, Thomas (2013). Antigens of the type-three secretion system of Aeromonas salmonicida subsp. salmonicida prevent protective immunity in rainbow trout. Vaccine, 31(45), pp. 5256-5261. Elsevier 10.1016/j.vaccine.2013.08.057

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Aeromonas salmonicida subsp. salmonicida is the etiologic agent of furunculosis, a frequent and significant disease of fisheries worldwide. The disease is largely controlled by commercial oil adjuvanted vaccines containing bacterins. However, the mechanisms leading to a protective immune response remain poorly understood. The type-three secretion system (T3SS) plays a central role in virulence of A. salmonicida subsp. salmonicida and thus may have an influence on the immune response of the host. The aim of this study was to evaluate the role of the T3SS antigens in mounting a protective immune response against furunculosis. Rainbow trout were intraperitoneally vaccinated in two independent experiments with bacterins prepared from a wild-type A. salmonicida strain and an isogenic strain carrying a deletion in the T3SS (ΔascV). Fish were challenged with the wt strain eight weeks after vaccination. In both trials, the survival rate of trout vaccinated with the ΔascV strain was significantly higher (23-28%) in comparison to the group vaccinated with the wt strain. High-throughput proteomics analysis of whole bacteria showed the ascV deletion in the mutant strain resulted in lower expression of all the components of the T3SS, several of which have a potential immunosuppressive activity. In a third experiment, fish were vaccinated with recombinant AcrV (homologous to the protective antigen LcrV of Yersinia) or S-layer protein VapA (control). AcrV vaccinated fish were not protected against a challenge while fish vaccinated with VapA were partially protected. The presence of T3SS proteins in the vaccine preparations decreased the level of protection against A. salmonicida infection and that AcrV was not a protective antigen. These results challenge the hypothesis that mounting specific antibodies against T3SS proteins should bring better protection to fish and demonstrate that further investigations are needed to better understand the mechanisms underlying effective immune responses against A. salmonicida infection.

Item Type:

Journal Article (Original Article)

Division/Institute:

05 Veterinary Medicine > Research Foci > Host-Pathogen Interaction
05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP)
05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP) > Institute of Veterinary Bacteriology
05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP) > Center for Fish and Wildlife Health (FIWI)

UniBE Contributor:

Benedicenti, Ottavia; von Siebenthal, Beat; Frey, Joachim and Wahli, Thomas

Subjects:

600 Technology > 630 Agriculture

ISSN:

0264-410X

Publisher:

Elsevier

Language:

English

Submitter:

Susanne Portner

Date Deposited:

22 Aug 2014 13:25

Last Modified:

11 Feb 2015 14:24

Publisher DOI:

10.1016/j.vaccine.2013.08.057

PubMed ID:

24012573

Uncontrolled Keywords:

Aeromonas salmonicida, Furunculosis, Type-three secretion system, T3SS, Vaccine, AcrV, Inhibition of immune protection

BORIS DOI:

10.7892/boris.43840

URI:

https://boris.unibe.ch/id/eprint/43840

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