Detection of type III secretion system genes in Aeromonas hydrophila and their relationship with virulence in Nile tilapia

Carvalho-Castro, G.A.; Lopes, CV; Leal, Carlos Augusto Gomes; Cardoso, Patrícia Gomes; Leite, Romário Cerqueira; Figueiredo, Henrique César Pereira

doi:10.1016/j.vetmic.2010.01.021

Cited by 25 publications

(18 citation statements)

References 22 publications

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“…Likewise, among the aerA + alt + ahp − , aerA + alt − ahp + and aerA − alt + ahp + strains, only SB94‐5, GY‐21 and HB04 were included in the virulent category. The similar phenomenon has been found in the previous report (Carvalho‐Castro et al. 2010) that mortality rates varied between 12·5 and 87·5% in the groups challenged with A. hydrophila ascV + / aopB + isolates.…”

Section: Discussionsupporting

confidence: 91%

“…Likewise, among the aerA + alt + ahp ) , aerA + alt ) ahp + and aerA ) alt + ahp + strains, only SB94-5, GY-21 and HB04 were included in the virulent category. The similar phenomenon has been found in the previous report (Carvalho-Castro et al 2010) that mortality rates varied between 12AE5 and 87AE5% in the groups challenged with A. hydrophila ascV + ⁄ aopB + isolates. One intriguing possibility is that some A. hydrophila strains possess a wide range of virulence factors, other than those tested by us, that enable them to evade the host defense system and spread, eventually killing the host.…”

Section: Discussionsupporting

confidence: 91%

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Detection of three virulence genes alt, ahp and aerA in Aeromonas hydrophila and their relationship with actual virulence to zebrafish

Liu

et al. 2011

Journal of Applied Microbiology

114

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Aims: To evaluate the frequency of the aerolysin (aerA), cytotoxic enterotoxin (alt) and serine protease (ahp) genes in Aeromonas hydrophila isolates from different sources, and to determine the relationship between the presence of these genes and virulence of A. hydrophila in zebrafish. Methods and Results: Aeromonas hydrophila isolates from clinical cases (n = 40), from healthy fish (n = 22) and from water environment (n = 21) were analysed with respect to the prevalence of aerA, alt and ahp genes by PCR assay. These virulence factors occur among clinical isolates as well as among isolates from healthy fish and water environment. The majority (97·6%) of the strains examined carried one or more virulence genes. The isolates were divided into seven genetic profiles on the basis of PCR result: aerA+alt+ahp+ (62·7%), aerA+alt+ahp− (13·3%), aerA+alt−ahp+ (10·8%), aerA−alt+ahp+ (4·8%), aerA−alt−ahp+ (3·6%), aerA+alt−ahp− (2·4%) and aerA−alt−ahp− (2·4%). A higher frequency of genetic group aerA+alt+ahp+ was determined in the isolates from diseased animals compared to those from healthy fish or water environments. Virulence properties of 26 representative strains belonging to the seven genetic profiles were further characterized. Results demonstrated that as the present of virulence genes increased, the proteolytic, haemolytic and cytotoxic activities of extracellular products also increased. And the 50% lethal doses (LD50s) of aerA+alt+ahp+ isolates (<105) in zebrafish were lower when compared with the strains expressing one or combinations of two virulence genes (>106). Conclusions: Virulence properties of A. hydrophila correlated well with the presence of virulence genes tested. aerA+alt+ahp+ was more frequent virulence genotype in A. hydrophila isolates from clinical diseases than from healthy fish and water environment, and the aerA+alt+ahp+ isolates were more virulent to zebrafish compared to the other six genetic profiles. Significant and Impact of the Study: The detection for aerA, alt and ahp can be used for virulence typing of A. hydrophila isolates.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 91%

Detection of three virulence genes alt, ahp and aerA in Aeromonas hydrophila and their relationship with actual virulence to zebrafish

Liu

et al. 2011

Journal of Applied Microbiology

114

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“…Contextually, the aexU and acrH genes are present in a minority of A. hydrophila and no experimental studies have been performed to establish their respective roles in virulence. While no experimental manipulations were performed, a subsequent study compared clinical and environmental isolates of A. hydrophila , showing that T3SS structural genes aopB and ascV are most abundant in A. hydrophila disease isolates (Carvalho-Castro et al, 2010), a link with virulence that is supported by the attenuation of virulence in A. piscicola AH-3 ascV mutants (Vilches et al, 2004). Collectively, these results appear to indicate that the T3SS is a strong contributing factor for virulence of Aeromonas spp.…”

Section: Secretion Systemsmentioning

confidence: 99%

Virulence Factors of Aeromonas hydrophila: In the Wake of Reclassification

et al. 2016

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The ubiquitous “jack-of-all-trades,” Aeromonas hydrophila, is a freshwater, Gram-negative bacterial pathogen under revision in regard to its phylogenetic and functional affiliation with other aeromonads. While virulence factors are expectedly diverse across A. hydrophila strains and closely related species, our mechanistic knowledge of the vast majority of these factors is based on the molecular characterization of the strains A. hydrophila AH-3 and SSU, which were reclassified as A. piscicola AH-3 in 2009 and A. dhakensis SSU in 2013. Individually, these reclassifications raise important questions involving the applicability of previous research on A. hydrophila virulence mechanisms; however, this issue is exacerbated by a lack of genomic data on other research strains. Collectively, these changes represent a fundamental gap in the literature on A. hydrophila and confirm the necessity of biochemical, molecular, and morphological techniques in the classification of research strains that are used as a foundation for future research. This review revisits what is known about virulence in A. hydrophila and the feasibility of using comparative genomics in light of this phylogenetic revision. Conflicting data between virulence factors, secretion systems, quorum sensing, and their effect on A. hydrophila pathogenicity appears to be an artifact of inappropriate taxonomic comparisons and/or be due to the fact that these properties are strain-specific. This review audits emerging data on dominant virulence factors that are present in both A. dhakensis and A. hydrophila in order to synthesize existing data with the aim of locating where future research is needed.

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“…Our laboratory group and others have characterized several virulence factors from Aeromonas species, which are secreted via the type 2 and type 3 secretion systems (Carvalho-Castro et al , 2010; Chopra et al , 2000; Sha et al , 2005, 2007; Sierra et al , 2007; Tan et al , 2008; Vilches et al , 2009). Our most recent studies are focused on the type 6 secretion system (T6SS) and its effectors from diarrhoeal isolate SSU of A. hydrophila (Suarez et al , 2008, 2010).…”

Section: Introductionmentioning

confidence: 99%

Role of Hcp, a type 6 secretion system effector, of Aeromonas hydrophila in modulating activation of host immune cells

et al. 2010

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Recently, we reported that the type 6 secretion system (T6SS) of Aeromonas hydrophila SSU plays an important role in bacterial virulence in a mouse model, and immunization of animals with the T6SS effector haemolysin co-regulated protein (Hcp) protected them against lethal infections with wild-type bacteria. Additionally, we showed that the mutant bacteria deleted for the vasH gene within the T6SS gene cluster did not express the hcp gene, while the vasK mutant could express and translocate Hcp, but was unable to secrete it into the extracellular milieu. Both of these A. hydrophila SSU mutants were readily phagocytosed by murine macrophages, pointing to the possible role of the secreted form of Hcp in the evasion of the host innate immunity. By using the ΔvasH mutant of A. hydrophila, our in vitro data showed that the addition of exogenous recombinant Hcp (rHcp) reduced bacterial uptake by macrophages. These results were substantiated by increased bacterial virulence when rHcp was added along with the ΔvasH mutant in a septicaemic mouse model of infection. Analysis of the cytokine profiling in the intraperitoneal lavage as well as activation of host cells after 4 h of infection with the ΔvasH mutant supplemented with rHcp indicated that this T6SS effector inhibited production of pro-inflammatory cytokines and induced immunosuppressive cytokines, such as interleukin-10 and transforming growth factor-β, which could circumvent macrophage activation and maturation. This mechanism of innate immune evasion by Hcp possibly inhibited the recruitment of cellular immune components, which allowed bacterial multiplication and dissemination in animals, thereby leading to their mortality.

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Detection of type III secretion system genes in Aeromonas hydrophila and their relationship with virulence in Nile tilapia

Cited by 25 publications

References 22 publications

Detection of three virulence genes alt, ahp and aerA in Aeromonas hydrophila and their relationship with actual virulence to zebrafish

Detection of three virulence genes alt, ahp and aerA in Aeromonas hydrophila and their relationship with actual virulence to zebrafish

Virulence Factors of Aeromonas hydrophila: In the Wake of Reclassification

Role of Hcp, a type 6 secretion system effector, of Aeromonas hydrophila in modulating activation of host immune cells

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