Surface-disorganized, attenuated mutants of Aeromonas salmonicida as furunculosis live vaccines

Thornton, Julian C.; Garduño, Rafael A.; Newman, Stephen G.; Kay, William W.

doi:10.1016/0882-4010(91)90002-r

Cited by 45 publications

(36 citation statements)

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“…However, our avirulent strains, which expressed the Alayer protein both in vitro and in vivo (data not shown), did not cause disease and were cleared from the host, indicating that the A-layer is not a sole determinant of virulence for ASS strains to persist in the host and to cause disease in turbot. This is not a surprising result since avirulent ASS strains that express the A-layer as well as virulent ASS strains that do not express the Alayer have been characterized in other studies (Sakai 1985, Ward et al 1985, Ellis et al 1988, Olivier 1990, Thornton et al 1991, Fernández et al 1995. Moreover, genetic tagging of the ASS strains with GFP is a useful method for investigating interactions between ASS and animal hosts like turbot.…”

Section: Discussionmentioning

confidence: 76%

Colonization of turbot tissues by virulent and avirulent Aeromonas salmonicida subsp. salmonicida strains during infection

Farto¹,

Milton²,

Bermúdez³

et al. 2011

Dis. Aquat. Org.

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Preventing disease outbreaks in cultured turbot Psetta maxima L. caused by Aeromonas salmonicida subsp. salmonicida (ASS) requires a better understanding of how this pathogen colonizes its host. Distribution of 1 virulent and 2 avirulent ASS strains in turbot tissues was investigated during early and late stages of infection following an immersion challenge. To track bacteria within the turbot, the ASS strains were tagged with green fluorescent protein (GFP). Both virulent and avirulent strains colonized the epidermal mucus, gills, and intestine within the first 12 h post challenge, suggesting that these sites may serve as points of entry into turbot. Although the avirulent strains colonized these initial sites in the turbot tissues, they were rarely found in the internal organs and were cleared from the host 4 d post challenge. In contrast, the virulent ASS strain was found in the liver and kidney as early as 12 h post challenge and was found in the muscle tissue at very late stages of infection. The virulent strain persisted in all tested host tissues until death occurred 7 d post challenge, suggesting that ASS must colonize and survive within the turbot tissues for an infection to result in death of the fish. Comparisons of the distribution profiles of both virulent and avirulent strains during early and late stages of an infection in turbot has provided important information on the route and persistence of an ASS infection in this host.KEY WORDS: Aeromonas salmonicida · Persistence · Turbot · Green fluorescent protein · GFP · Immersion challenge Resale or republication not permitted without written consent of the publisherDis Aquat Org 95: [167][168][169][170][171][172][173] 2011 for ASS in other internal organs and did not analyze the transmission of the bacteria through the internal tissues. Interestingly, Hodgkinson et al. (1987) compared infectivity of virulent and avirulent strains in salmonids but only during the first 24 h post challenge, showing inconclusive results since the virulent strain showed an avirulent behavior. Thus, additional studies are needed to investigate the fate of both virulent and avirulent ASS strains during the progression of early and late stages of disease. In particular, studies using non-salmonid fish such as turbot will give a broader understanding on how ASS colonizes its host and will provide information for the design of new therapeutic strategies to protect against this pathogen in aquaculture.The green fluorescent protein (GFP) from Aequorea victoria has been used successfully as a genetic marker for the detection of bacterial pathogens during the infection of fish (Ling et al. 2000, 2001, O'Toole et al. 2004, Welch & Wiens 2005, Chu & Lu 2008. In most cases, expression of GFP in the bacterial cell does not interfere with growth or virulence (Chalfie et al. 1994, Valdivia et al. 1996, Ling et al. 2000, Chu & Lu 2008. In addition, GFP fluorescence, which is induced by UV light, facilitates visualization of bacteria in fish tissues and the quantification o...

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Section: Discussionmentioning

confidence: 76%

Colonization of turbot tissues by virulent and avirulent Aeromonas salmonicida subsp. salmonicida strains during infection

Farto¹,

Milton²,

Bermúdez³

et al. 2011

Dis. Aquat. Org.

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“…Furthermore, in our examination of the aborted infectious process of the ⌬PGM mutant, we observed the mutant to disseminate to multiple organs within 4 h but to be rapidly cleared from blood and brain while persisting at diminished levels in splenic tissue for up to 5 days after infection. The use of live attenuated vaccines in aquaculture could offer benefits, including elicitation of mucosal immunity, longer presentation time of unaltered antigens, and stimulation of both cell-mediated and humoral immunity (28,29,41). A number of recent studies of fish have found live attenuated vaccines against other bacterial pathogens to be effective (9,22,28), and the development of a successful live attenuated vaccine to treat the globally important fish pathogen S. iniae would be greatly welcomed.…”

Section: Discussionmentioning

confidence: 99%

Streptococcus iniae Phosphoglucomutase Is a Virulence Factor and a Target for Vaccine Development

Buchanan¹,

et al. 2005

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Streptococcus iniae represents a major health and economic problem in fish species worldwide. Random Tn917 mutagenesis and high-throughput screening in a hybrid striped bass (HSB) model of meningoencephalitis identified attenuated S. iniae mutants. The Tn917 insertion in one mutant disrupted an S. iniae homologue of a phosphoglucomutase (pgm) gene. Electron microscopy revealed a decrease in capsule thickness and cell wall rigidity, with ⌬PGM mutant cells reaching sizes ϳ3-fold larger than those of the wild type (WT). The ⌬PGM mutant was cleared more rapidly in HSB blood and was more sensitive to killing by cationic antimicrobial peptides including moronecidin from HSB. In vivo, the ⌬PGM mutant was severely attenuated in HSB, as intraperitoneal challenge with 1,000 times the WT lethal dose produced only 2.5% mortality. Reintroduction of an intact copy of the S. iniae pgm gene on a plasmid vector restored antimicrobial peptide resistance and virulence to the ⌬PGM mutant. In analysis of the aborted infectious process, we found that ⌬PGM mutant organisms initially disseminated to the blood, brain, and spleen but were eliminated by 24 h without end organ damage. Ninety to 100% of fish injected with the ⌬PGM mutant and later challenged with a lethal dose of WT S. iniae survived. We conclude that the pgm gene is required for virulence in S. iniae, playing a role in normal cell wall morphology, surface capsule expression, and resistance to innate immune clearance mechanisms. An S. iniae ⌬PGM mutant is able to stimulate a protective immune response and may have value as a live attenuated vaccine for aquaculture.With increased development of intensive operations, disease has become a significant hurdle to the profitable culture of fish and shellfish. Streptococcal infections in fish, in particular those produced by the pathogen Streptococcus iniae, have increased markedly with intensification of aquaculture practices (37). S. iniae causes a fatal meningoencephalitis and is associated with large-scale mortality in a wide variety of marine and freshwater cultured fish species, as well as in wild species (5,39,46). More than 30 species of fish have documented susceptibility to S. iniae disease, including trout (10), yellowtail (19), tilapia (39), barramundi (6), and hybrid striped bass (HSB) (11). S. iniae is distributed globally and is estimated to cause yearly economic losses of hundreds of millions of dollars. Occasionally, S. iniae can cause serious zoonotic infections in humans who injure themselves while handling infected fish (20,42).Relatively little is known of the genetics of S. iniae or of the pathogenic mechanisms underlying its virulence. Here, we describe a severely attenuated mutant of S. iniae, identified through random transposon mutagenesis and direct screening for virulence in HSB. Analysis of the transposon insertion site revealed a disruption of an open reading frame (ORF) with similarity to bacterial phosphoglucomutase (pgm) genes. The enzyme phosphoglucomutase (PGM) interconverts glucose-6-phosphate an...

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“…In recent years a number of furunculosis vaccine strains have become available, including a recently developed, live attenuated strain which provides considerable protection against furunculosis in trials ( Thornton et al, 1991Thornton et al, , 1994. However, the majority of strains developed for vaccine use are not well characterised at a genetic level and mutations in vaccine strains are ill-defined.…”

Section: Molecular Approaches To Vaccine Developmentmentioning

confidence: 99%

A molecular approach to understanding the pathogenesis of : relevance to vaccine development

Trust

Noonan

Chu

et al. 1996

Fish & Shellfish Immunology

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Surface-disorganized, attenuated mutants of Aeromonas salmonicida as furunculosis live vaccines

Cited by 45 publications

References 36 publications

Colonization of turbot tissues by virulent and avirulent Aeromonas salmonicida subsp. salmonicida strains during infection

Colonization of turbot tissues by virulent and avirulent Aeromonas salmonicida subsp. salmonicida strains during infection

Streptococcus iniae Phosphoglucomutase Is a Virulence Factor and a Target for Vaccine Development

A molecular approach to understanding the pathogenesis of : relevance to vaccine development

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Surface-disorganized, attenuated mutants of Aeromonas salmonicida as furunculosis live vaccines

Cited by 45 publications

References 36 publications

Colonization of turbot tissues by virulent and ­avirulent Aeromonas salmonicida subsp. ­salmonicida strains during infection

Colonization of turbot tissues by virulent and ­avirulent Aeromonas salmonicida subsp. ­salmonicida strains during infection

Streptococcus iniae Phosphoglucomutase Is a Virulence Factor and a Target for Vaccine Development

A molecular approach to understanding the pathogenesis of : relevance to vaccine development

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Colonization of turbot tissues by virulent and avirulent Aeromonas salmonicida subsp. salmonicida strains during infection

Colonization of turbot tissues by virulent and avirulent Aeromonas salmonicida subsp. salmonicida strains during infection