Comparative genomics of Riemerella anatipestifer reveals genetic diversity

Wang, Xiaojia; Liu, Wenbin; Zhu, Dekang; Yang, L.; Liu, Mafeng; Yin, Sanjun; Wang, Mingshu; Jia, Renyong; Chen, Shun; Sun, Kunfeng; Cheng, Anchun; Chen, Xiaoyue

doi:10.1186/1471-2164-15-479

Cited by 49 publications

(41 citation statements)

References 46 publications

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“…Virulence evaluation of different R. anatipestifer isolates in ducklings and G. mellonella larvae. The degrees of virulence of two different R. anatipestifer isolates, R. anatipestifer ATCC 11845 and R. anatipestifer CH-1 (28), were first assessed in the duckling infection model. As Fig.…”

Section: Resultsmentioning

confidence: 99%

New Perspectives on Galleria mellonella Larvae as a Host Model Using Riemerella anatipestifer as a Proof of Concept

Liu

Huang

et al. 2019

Infect Immun

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Galleria mellonella larvae have been used as a host model to study interactions between pathogens and hosts for several years. However, whether the model is useful to interrogate Riemerella anatipestifer infection biology remained unknown. This study aimed to exploit the potential of G. mellonella larvae and reveal their limitations as a host model for R. anatipestifer infection. G. mellonella larvae were shown to be effective for virulence evaluations of different R. anatipestifer strains. Furthermore, the virulent strain R. anatipestifer CH-1 had a stronger ability to proliferate than the attenuated strain R. anatipestifer ATCC 11845 in both G. mellonella larvae and ducklings. Unconventionally it was shown that G. mellonella larvae cannot be used to evaluate the efficacy of antimicrobials and their combinations. Additionally, it was shown that certain virulence factors, such as OmpA (B739_0861), B739_1208, B739_1343, and Wza (B739_1124), were specific only for ducklings, suggesting that G. mellonella larvae must be cautiously used to identify virulence factors of R. anatipestifer. Evaluation of heme uptake-related virulence genes, such as tonB1 and tonB2, required preincubating the strains with hemoglobin before infection of G. mellonella larvae since R. anatipestifer cannot obtain a heme source from G. mellonella larvae. In conclusion, this study revealed the applicability and limitations of G. mellonella as a model with which to study the pathogen-host interaction, particularly in the context of R. anatipestifer infection.A fter Robert Koch's work, Stanley Falkow established the molecular version of Koch's postulates, which have guided the study of the microbial virulence determinants in infectious diseases since the late 1980s (1). One of the key purposes of the molecular version of Koch's postulates is to test whether a microorganism is attenuated when a candidate virulence gene is inactivated. Thus, the use of animal models to identify the virulence factors of pathogens is indispensable. However, animal models are accompanied by ethical problems and cannot be used in large numbers for statistical analysis. Recently, nonmammalian models, including Caenorhabditis elegans, Drosophila melanogaster, Danio rerio, and larvae of the greater wax moth, Galleria mellonella, have been used for biological research (2-4). These organisms share many advantages over mammalian models, including being easy to obtain, cost-effective, and more ethically acceptable. However, the optimal temperature for C. elegans, D. melanogaster, and Danio rerio is below 28°C (5, 6). These models are defective since the optimum temperature for most mammal pathogens is 37°C. In contrast, the G. mellonella larva model is able to survive at 37°C. Moreover, the immune system of G. mellonella larvae

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Section: Resultsmentioning

confidence: 99%

New Perspectives on Galleria mellonella Larvae as a Host Model Using Riemerella anatipestifer as a Proof of Concept

Liu

Huang

et al. 2019

Infect Immun

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“…These previous results suggested that TonB-dependent pathways may play important roles in R. anatipestifer iron acquisition. According to the full genome sequences of four R. anatipestifer strains in GenBank, this bacterium is predicted to contain two TonB-ExbB-ExbD systems (Mavromatis et al, 2011;Wang et al, 2014;Yuan et al, 2011). In this study, by deleting the tonB1 or tonB2 gene from R. anatipestifer strain CH3, the roles of the two TonB proteins in haemin iron acquisition and pathogenesis were investigated.…”

Section: Introductionmentioning

confidence: 98%

Roles of the TonB1 and TonB2 proteins in haemin iron acquisition and virulence in Riemerella anatipestifer

Miao

Xing

et al. 2015

Microbiology

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Two TonB systems in Riemerella anatipestifer were found and characterized as ExbB1-ExbD1-TonB1 and ExbB2-ExbD2-ExbD29-TonB2, but the significance of two sets of TonB complexes in R. anatipestifer is not clear. In this study, by deleting the tonB1 or tonB2 gene of R. anatipestifer strain CH3, we investigated the roles of the TonB1 and TonB2 proteins in iron acquisition and virulence. The results showed that strain CH3 could utilize haemin as the sole iron source in the presence of L-cysteine, but haemin iron acquisition was defective in the CH3DtonB1 mutant, and the deletion of either tonB1 or tonB2 significantly reduced adhesion to and invasion of Vero cells. Animal experiments indicated that the LD 50 of the CH3DtonB1 and CH3DtonB2 mutants in ducklings was ,224-and ,87-fold, respectively, higher than that of the WT CH3 strain. Additional analysis indicated that blood bacterial loading of ducklings infected with CH3DtonB1 or CH3DtonB2 decreased significantly compared with that found for WT CH3-infected ducklings. Thus, our results indicated that the TonB1, but not TonB2 protein, is involved in haemin iron acquisition and that both TonB proteins are necessary for optimal bacterial virulence.

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“…Among them, serotypes 1, 2, 3, 5, and 15 are the major pathogens affecting the duck industry. No cross protection has been found among these serotypes56. RA infection produces mortality and morbidity rates ranging between 10 and 30%, but mortality rates as high as 75% have been reported in infected duck farms7.…”

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Investigation of TbfA in Riemerella anatipestifer using plasmid-based methods for gene over-expression and knockdown

Liu

Wang

Zhu

et al. 2016

Sci Rep

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Riemerella anatipestifer is a duck pathogen that has caused serious economic losses to the duck industry worldwide. Despite this, there are few reported studies of the physiological and pathogenic mechanisms of Riemerella anatipestifer infection. In previous study, we have shown that TonB1 and TonB2 were involved in hemin uptake. TonB family protein (TbfA) was not investigated, since knockout of this gene was not successful at that time. Here, we used a plasmid based gene over-expression and knockdown to investigate its function. First, we constructed three Escherichia-Riemerella anatipestifer shuttle vectors containing three different native Riemerella anatipestifer promoters. The shuttle plasmids were introduced into Riemerella anatipestifer ATCC11845 by conjugation at an efficiency of 5 × 10−5 antibiotic-resistant transconjugants per recipient cell. Based on the high-expression shuttle vector pLMF03, a method for gene knockdown was established. Knockdown of TbfA in Riemerella anatipestifer ATCC11845 decreased the organism’s growth ability in TSB medium but did not affect its hemin utilization. In contrast, over-expression of TbfA in Riemerella anatipestifer ATCC11845ΔtonB1ΔtonB2. Significantly promoted the organism’s growth in TSB medium but significantly inhibited its hemin utilization. Collectively, these findings suggest that TbfA is not involved in hemin utilization by Riemerella anatipestifer.

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Comparative genomics of Riemerella anatipestifer reveals genetic diversity

Cited by 49 publications

References 46 publications

New Perspectives on Galleria mellonella Larvae as a Host Model Using Riemerella anatipestifer as a Proof of Concept

New Perspectives on Galleria mellonella Larvae as a Host Model Using Riemerella anatipestifer as a Proof of Concept

Roles of the TonB1 and TonB2 proteins in haemin iron acquisition and virulence in Riemerella anatipestifer

Investigation of TbfA in Riemerella anatipestifer using plasmid-based methods for gene over-expression and knockdown

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