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Matrix-assisted laser desorption ionization-time of flight mass spectrometry based identification of Edwardsiella ictaluri isolated from Vietnamese striped catfish ( Pangasius hypothalamus )

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ABSTRACT

Edwardsiella (E.) ictaluri is a major bacterial pathogen that affects commercially farmed striped catfish (Pangasius hypothalamus) in Vietnam. In a previous study, 19 strains of E. ictaluri collected from striped catfish were biochemically identified with an API-20E system. Here, the same 19 strains were used to assess the ability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS; applied using a MALDI Biotyper) to conduct rapid, easy and accurate identification of E. ictaluri. MALDI-TOF MS could directly detect the specific peptide patterns of cultured E. ictaluri colonies with high (> 2.0, indicating species-level identification) scores. MALDI Biotyper 3.0 software revealed that all of the strains examined in this study possessed highly similar peptide peak patterns. In addition, electrophoresis (SDS-PAGE) and subsequent immuno-blotting using a specific chicken antibody (IgY) against E. ictaluri revealed that the isolates had highly similar protein profiles and antigenic banding profiles. The results of this study suggest that E. ictaluri isolated from striped catfish in Vietnam have homologous protein compositions. This is important, because it indicates that MALDI-TOF MS analysis could potentially outperform the conventional methods of identifying E. ictaluri.

No MeSH data available.


Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) spectral profiles of three representative Edwardsiella (E.) ictaluri strains, as generated using the flex Analysis software and a MALDI Biotyper system. The relative intensities of the ions are shown on the Y-axis, and the ion masses (in Daltons) are shown on the X-axis. The m/z value gives the mass-to-charge ratio. Peptide peaks common to all strains are indicated with arrow heads above the panel, and the peaks with black lines in the panel represent different peaks between the four strains. a.u., arbitrary units.
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Figure 1: Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) spectral profiles of three representative Edwardsiella (E.) ictaluri strains, as generated using the flex Analysis software and a MALDI Biotyper system. The relative intensities of the ions are shown on the Y-axis, and the ion masses (in Daltons) are shown on the X-axis. The m/z value gives the mass-to-charge ratio. Peptide peaks common to all strains are indicated with arrow heads above the panel, and the peaks with black lines in the panel represent different peaks between the four strains. a.u., arbitrary units.

Mentions: Nineteen previously characterized E. ictaluri strains and reference strain ATCC33202 were analyzed by MALDI-TOF MS, and the obtained spectra were compared with those in the Bruker database. All of the examined strains were identified as E. ictaluri at the species level. Specifically, 65% (13/20) were identified with log scores > 2.3, while 35% (7/20) had log scores between 2.0 and 2.3. No strain showed a log score < 2.0 (Table 1). It took less than 60 min from initial sample preparation to obtain the identification results. Importantly, while the mass intensities were diverse, most of the peak patterns were quite similar among the striped catfish isolates and ATCC33202 (e.g., peaks at 2658, 5321, 6259, 9281, 9465 and 11,542 Da) (Fig. 1).


Matrix-assisted laser desorption ionization-time of flight mass spectrometry based identification of Edwardsiella ictaluri isolated from Vietnamese striped catfish ( Pangasius hypothalamus )
Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) spectral profiles of three representative Edwardsiella (E.) ictaluri strains, as generated using the flex Analysis software and a MALDI Biotyper system. The relative intensities of the ions are shown on the Y-axis, and the ion masses (in Daltons) are shown on the X-axis. The m/z value gives the mass-to-charge ratio. Peptide peaks common to all strains are indicated with arrow heads above the panel, and the peaks with black lines in the panel represent different peaks between the four strains. a.u., arbitrary units.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037306&req=5

Figure 1: Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) spectral profiles of three representative Edwardsiella (E.) ictaluri strains, as generated using the flex Analysis software and a MALDI Biotyper system. The relative intensities of the ions are shown on the Y-axis, and the ion masses (in Daltons) are shown on the X-axis. The m/z value gives the mass-to-charge ratio. Peptide peaks common to all strains are indicated with arrow heads above the panel, and the peaks with black lines in the panel represent different peaks between the four strains. a.u., arbitrary units.
Mentions: Nineteen previously characterized E. ictaluri strains and reference strain ATCC33202 were analyzed by MALDI-TOF MS, and the obtained spectra were compared with those in the Bruker database. All of the examined strains were identified as E. ictaluri at the species level. Specifically, 65% (13/20) were identified with log scores > 2.3, while 35% (7/20) had log scores between 2.0 and 2.3. No strain showed a log score < 2.0 (Table 1). It took less than 60 min from initial sample preparation to obtain the identification results. Importantly, while the mass intensities were diverse, most of the peak patterns were quite similar among the striped catfish isolates and ATCC33202 (e.g., peaks at 2658, 5321, 6259, 9281, 9465 and 11,542 Da) (Fig. 1).

View Article: PubMed Central - PubMed

ABSTRACT

Edwardsiella (E.) ictaluri is a major bacterial pathogen that affects commercially farmed striped catfish (Pangasius hypothalamus) in Vietnam. In a previous study, 19 strains of E. ictaluri collected from striped catfish were biochemically identified with an API-20E system. Here, the same 19 strains were used to assess the ability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS; applied using a MALDI Biotyper) to conduct rapid, easy and accurate identification of E. ictaluri. MALDI-TOF MS could directly detect the specific peptide patterns of cultured E. ictaluri colonies with high (&gt; 2.0, indicating species-level identification) scores. MALDI Biotyper 3.0 software revealed that all of the strains examined in this study possessed highly similar peptide peak patterns. In addition, electrophoresis (SDS-PAGE) and subsequent immuno-blotting using a specific chicken antibody (IgY) against E. ictaluri revealed that the isolates had highly similar protein profiles and antigenic banding profiles. The results of this study suggest that E. ictaluri isolated from striped catfish in Vietnam have homologous protein compositions. This is important, because it indicates that MALDI-TOF MS analysis could potentially outperform the conventional methods of identifying E. ictaluri.

No MeSH data available.