Food Forensics: Using Mass Spectrometry To Detect Foodborne Protein Contaminants, as Exemplified by Shiga Toxin Variants and Prion Strains

2018 ◽  
Vol 66 (32) ◽  
pp. 8435-8450 ◽  
Author(s):  
Christopher J. Silva
Keyword(s):  
Mass Spectrometry ◽  
Shiga Toxin ◽  
Prion Strains

scholarly journals Top-Down Proteomic Identification of Shiga Toxin 1 and 2 from Pathogenic Escherichia coli Using MALDI-TOF-TOF Tandem Mass Spectrometry

2019 ◽  
Vol 7 (11) ◽  
pp. 488 ◽  
Author(s):  
Clifton K. Fagerquist ◽  
William J. Zaragoza ◽  
Michelle Q. Carter
Keyword(s):  
Mass Spectrometry ◽  
Escherichia Coli ◽  
Tandem Mass Spectrometry ◽  
Disulfide Bond ◽  
Shiga Toxin ◽  
Tandem Mass ◽  
Top Down ◽  
E Coli ◽  
B Subunit ◽  
Proteomic Identification

Shiga-toxin-producing Escherichia coli (STEC) are a burden on agriculture and a threat to public health. Rapid methods are needed to identify STEC strains and characterize the Shiga toxin (Stx) they produce. We analyzed three STEC strains for Stx expression, using antibiotic induction, matrix-assisted laser desorption/ionization time-of-flight-time-of-flight (MALDI-TOF-TOF) mass spectrometry, and top-down proteomic analysis. E. coli O157:H- strain 493/89 is a clinical isolate linked to an outbreak of hemolytic uremic syndrome (HUS) in Germany in the late 1980s. E. coli O145:H28 strains RM12367-C1 and RM14496-C1 were isolated from an agricultural region in California. The stx operon of the two environmental strains were determined by whole genome sequencing (WGS). STEC strain 493/89 expressed Shiga toxin 2a (Stx2a) as identified by tandem mass spectrometry (MS/MS) of its B-subunit that allowed identification of the type and subtype of the toxin. RM12367-C1 also expressed Stx2a as identified by its B-subunit. RM14496-C1 expressed Shiga toxin 1a (Stx1a) as identified from its B-subunit. The B-subunits of Stx1 and Stx2 both have an intramolecular disulfide bond. MS/MS was obtained on both the disulfide-bond-intact and disulfide-bond-reduced B-subunit, with the latter being used for top-down proteomic identification. Top-down proteomic analysis was consistent with WGS.

scholarly journals Top-down and middle-down proteomic analysis of Shiga toxin using MALDI-TOF-TOF mass spectrometry

MethodsX ◽  
2019 ◽  
Vol 6 ◽  
pp. 815-826 ◽  
Author(s):  
Clifton K. Fagerquist ◽  
William J. Zaragoza
Keyword(s):  
Mass Spectrometry ◽  
Shiga Toxin ◽  
Proteomic Analysis ◽  
Top Down ◽  
Maldi Tof

scholarly journals Determination of Serotypes of Shiga Toxin-ProducingEscherichia coliIsolates by Intact Cell Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry

2010 ◽  
Vol 77 (3) ◽  
pp. 896-905 ◽  
Author(s):  
Axel Karger ◽  
Mario Ziller ◽  
Barbara Bettin ◽  
Birgit Mintel ◽  
Susann Schares ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Shiga Toxin ◽  
Mass Spectra ◽  
Intact Cell ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
E Coli ◽  
Desorption Ionization ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

ABSTRACTShiga toxin-producingEscherichia coli(STEC) isolates representing the serotypes O165:H25, O26:H11/H32, and O156:H25 were analyzed by matrix-assisted laser desorption/ionization (MALDI) mass spectra of whole cells, a procedure also known as intact cell mass spectrometry (ICMS or IC-MALDI MS) or MALDI-typing. We demonstrate that within the given species the three serotypes can be well discriminated by ICMS. Conditions for the construction of serotype-specific prototypic mass spectra were systematically optimized by filtering out masses that do not contribute to the discrimination of the serotypes. Binary distances between prototypic spectra and sample spectra were used to determine serotypes of unknown samples. With parameters optimized, only 0.7% of the assignments were incorrect compared to 31% when distances were calculated from alignments of unfiltered mass spectra. Within the different serotypes, clusters of genetically relatedE. colimost probably originating from single clones could be distinguished by restriction fragment length polymorphism analysis. Since ICMS did not reproduce these clusters, we conclude that the power of ICMS is just sufficient to discriminateE. coliserotypes under certain conditions but fails for the differentiation ofE. colibelow this level.

Mass spectrometry-based Shiga toxin identification: An optimized approach

2018 ◽  
Vol 180 ◽  
pp. 36-40 ◽  
Author(s):  
Keding Cheng ◽  
Angela Sloan ◽  
Xingle Li ◽  
Glen D. Armstrong ◽  
Gehua Wang
Keyword(s):  
Mass Spectrometry ◽  
Shiga Toxin

scholarly journals Phenotypic H-Antigen Typing by Mass Spectrometry Combined with Genetic Typing of H Antigens, O Antigens, and Toxins by Whole-Genome Sequencing Enhances Identification of Escherichia coli Isolates

2016 ◽  
Vol 54 (8) ◽  
pp. 2162-2168 ◽  
Author(s):  
Keding Cheng ◽  
Huixia Chui ◽  
Larissa Domish ◽  
Angela Sloan ◽  
Drexler Hernandez ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Escherichia Coli ◽  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Shiga Toxin ◽  
Gene Pair ◽  
Whole Genome ◽  
Genetic Typing ◽  
Content Type ◽  
O Antigens

Mass spectrometry-based phenotypic H-antigen typing (MS-H) combined with whole-genome-sequencing-based genetic identification of H antigens, O antigens, and toxins (WGS-HOT) was used to type 60 clinicalEscherichia coliisolates, 43 of which were previously identified as nonmotile, H type undetermined, or O rough by serotyping or having shown discordant MS-H and serotyping results. Whole-genome sequencing confirmed that MS-H was able to provide more accurate data regarding H antigen expression than serotyping. Further, enhanced and more confident O antigen identification resulted from gene cluster based typing in combination with conventional typing based on the gene pair comprisingwzxandwzyand that comprisingwzmandwzt. The O antigen was identified in 94.6% of the isolates when the two genetic O typing approaches (gene pair and gene cluster) were used in conjunction, in comparison to 78.6% when the gene pair database was used alone. In addition, 98.2% of the isolates showed the existence of genes for various toxins and/or virulence factors, among which verotoxins (Shiga toxin 1 and/or Shiga toxin 2) were 100% concordant with conventional PCR based testing results. With more applications of mass spectrometry and whole-genome sequencing in clinical microbiology laboratories, this combined phenotypic and genetic typing platform (MS-H plus WGS-HOT) should be ideal for pathogenicE. colityping.

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