Dataset Information

Identification of antigenic proteins of the nosocomial pathogen Klebsiella pneumoniae.

ABSTRACT: The continuous expansion of nosocomial infections around the globe has become a precarious situation. Key challenges include mounting dissemination of multiple resistances to antibiotics, the easy transmission and the growing mortality rates of hospital-acquired bacterial diseases. Thus, new ways to rapidly detect these infections are vital. Consequently, researchers around the globe pursue innovative approaches for point-of-care devices. In many cases the specific interaction of an antigen and a corresponding antibody is pivotal. However, the knowledge about suitable antigens is lacking. The aim of this study was to identify novel antigens as specific diagnostic markers. Additionally, these proteins might be aptly used for the generation of vaccines to improve current treatment options. Hence, a cDNA-based expression library was constructed and screened via microarrays to detect novel antigens of Klebsiella pneumoniae, a prominent agent of nosocomial infections well-known for its extensive antibiotics resistance, especially by extended-spectrum beta-lactamases (ESBL). After screening 1536 clones, 14 previously unknown immunogenic proteins were identified. Subsequently, each protein was expressed in full-length and its immunodominant character examined by ELISA and microarray analyses. Consequently, six proteins were selected for epitope mapping and three thereof possessed linear epitopes. After specificity analysis, homology survey and 3d structural modelling, one epitope sequence GAVVALSTTFA of KPN_00363, an ion channel protein, was identified harboring specificity for K. pneumoniae. The remaining epitopes showed ambiguous results regarding the specificity for K. pneumoniae. The approach adopted herein has been successfully utilized to discover novel antigens of Campylobacter jejuni and Salmonella enterica antigens before. Now, we have transferred this knowledge to the key nosocomial agent, K. pneumoniae. By identifying several novel antigens and their linear epitope sites, we have paved the way for crucial future research and applications including the design of point-of-care devices, vaccine development and serological screenings for a highly relevant nosocomial pathogen.

SUBMITTER: Hoppe S

PROVIDER: S-EPMC4205017 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Identification of antigenic proteins of the nosocomial pathogen Klebsiella pneumoniae.

Hoppe Sebastian S Bier Frank F FF von Nickisch-Rosenegk Markus M

PloS one 20141021 10

The continuous expansion of nosocomial infections around the globe has become a precarious situation. Key challenges include mounting dissemination of multiple resistances to antibiotics, the easy transmission and the growing mortality rates of hospital-acquired bacterial diseases. Thus, new ways to rapidly detect these infections are vital. Consequently, researchers around the globe pursue innovative approaches for point-of-care devices. In many cases the specific interaction of an antigen and ...[more]

PMID: 25333280

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Project description:Klebsiella pneumoniae is emerging as an important nosocomial pathogen due to its rapidly increasing multidrug resistance, which has led to a renewed interest in polymyxin antibiotics, such as colistin, as antibiotics of last resort. However, heteroresistance (i.e., the presence of a subpopulation of resistant bacteria in an otherwise susceptible culture) may hamper the effectiveness of colistin treatment in patients. In a previous study, we showed that colistin resistance among extended-spectrum-beta-lactamase (ESBL)-producing K. pneumoniae isolates emerged after the introduction of selective digestive tract decontamination (SDD) in an intensive care unit (ICU). In this study, we investigated heteroresistance to colistin among ESBL-producing K. pneumoniae isolates by using population analysis profiles (PAPs). We used whole-genome sequencing (WGS) to identify the mutations that were associated with the emergence of colistin resistance in these K. pneumoniae isolates. We found five heteroresistant subpopulations, with colistin MICs ranging from 8 to 64 mg/liter, which were derived from five clonally related, colistin-susceptible clinical isolates. WGS revealed the presence of mutations in the lpxM, mgrB, phoQ, and yciM genes in colistin-resistant K. pneumoniae isolates. In two strains, mgrB was inactivated by an IS3-like or ISKpn14 insertion sequence element. Complementation in trans with the wild-type mgrB gene resulted in these strains reverting to colistin susceptibility. The MICs for colistin-susceptible strains increased 2- to 4-fold in the presence of the mutated phoQ, lpxM, and yciM alleles. In conclusion, the present study indicates that heteroresistant K. pneumoniae subpopulations may be selected for upon exposure to colistin. Mutations in mgrB and phoQ have previously been associated with colistin resistance, but we provide experimental evidence for roles of mutations in the yciM and lpxM genes in the emergence of colistin resistance in K. pneumoniae.

Project description:The screening of a cDNA derived expression library of Klebsiella pneumoniae MGH 78578 expressed in E.coli using a fusion construct and specific HaloTag interaction to a modified surface is shown. Thus, 1536 different clones were screened including positive (ompA, mdh) and negative (pyrC, gapA) reference proteins. The goal of the screening was to identify potential novel immunogenic proteins from K. pneumoniae by selecting clones showing a high signal intensity in comparison to the known antigens used as positve markers. Afterwards, the most promising clones were sequenced to identify the gene and corresponding protein and these proteins were then investigated further. Consequently, 14 novel immunogenic proteins could be identified. In total 1536 (4 x 384) different lysates were spotted on different microarray slides. Each slides contained 3600 distinct spots, seperated into two compartments of 1800 spots each. Each compartment comprised quadruplicate replicates of each sample lysate with controls being analysed with more replicates. As controls we used: ompA1, ompA2 and mdh (3 x 40 replicates) as positive reference proteins, as they have been described as immunogenic before. gapA and pyrC (2 x 40 replicates) as negative reference proteins, additionally two sets of E.coli cell lysates without fusionprotein expressed, namely Acella electrocompetent cells (40 replicates) and KRX (32 replicates). Last but not least a buffer control (24 replicates) was included. Therefore, each set of replicate slides contained 376 different samples and 8 controls. Each screening was performed with three replicate slides. Consequently, a total number of 12 slides were screened (4 sets of samples x 3 replicates). For identification rabbit polyclonal antibody to K. pneumoniae (Acris AP00792PU-N) as primary and Goat polyclonal to Rabbit IgG conjugated with ChromeoTM-546 (Abcam ab60317) as secondary antibody were used. The top compartment was incubated first with primary antibody, while the bottom compartment was incubated with PBS at the same time. Afterwards both compartments were incubated with secondary antibody.

Dataset Information

Identification of antigenic proteins of the nosocomial pathogen Klebsiella pneumoniae.

Publications

Identification of antigenic proteins of the nosocomial pathogen Klebsiella pneumoniae.

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