The role of probiotics in host-pathogen interaction at the first stages of Salmonella enterica infection

Organisation: Wrocław University of Environmental and Life Sciences, Wrocław
Position: PhD Candidate

Requirements:

Concerning the scholarship for a Ph.D. student, we will apply the general criteria formulated by the National Science Center in Poland and the following additional criteria:

• Candidate must hold a Master’s degree in veterinary medicine, microbiology, biotechnology,
  or in a related field or be a student in the last year of the Master's degree program in one of the aforementioned fields.
• Experience in laboratory work:

1. Molecular biology skills: PCR methods, DNA electrophoresis, DNA/RNA extraction, plasmid isolation, generation of deletion mutants, cloning
2. Cell biology skills: in vitro culture of cell lines, adhesion and invasion assay, fluorescence microscopy
3. Microbiology skills: cultivation of bacteria, adhesion and invasion assays;
4. Protein skills: protein purification, SDS PAGE, Western blot, ELISA;
5. Ability to work with animals in a research setting.

• Additional requirements:

1. Molecular biology skills: PCR methods, DNA electrophoresis, DNA/RNA extraction, plasmid isolation, generation of deletion mutants, cloning;
2. Sound understanding of molecular mechanisms of bacterial pathogenesis (with particular emphasis on the Salmonella genus);
3. Basic proficiency in the use of biological databases and online resources/tools;
4. Good written and spoken English communication skills.

Responsibilities:

It is expected that Ph.D. student will actively research the area related to the research grant, towards writing a Ph.D. thesis related to the project’s topic. This will be done alongside and under the supervision of the Principal Investigator.

The tasks will include:

• Screening for probiotic adhesive properties
• Participating in the generation of probiotic mutants with increased adhesion properties
• Characterization of generated mutants
• Cell line adhesion and invasion assays with the use of Salmonella and modified probiotics;
• Participation in in vivo studies utilizing a mouse model of Salmonella infection;
• Analyzing of the innate immune response during Salmonella infection in the presence of wild type and modified probiotics under the PI supervision
• Data interpretation and statistical analysis
• Attendance at national and international conferences (oral and poster presentation);
• Preparation of the research manuscripts based on results of investigations;
• regular work at the Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences.

Required documents:

Candidates should submit the following documents:

• motivation letter describing research competencies and motivation to engage in the project,
• scan of a document confirming receipt of the Master's degree or fifth-year student status,
• confirmation of B2 English level,
• scientific CV in English containing:
  -    description of research experience,
  -     list of publications - also those in preparation,
  -     list of conference presentations,
  -     list of awards and achievements regarding scientific work. 

We offer:

• doctoral scholarships for 48 months,
• doctoral scholarships shall amount toPLN 5,000 per month (gross)
• financial support for conducting studies that are research tasks in the project and attending conferences to present results of the project,
• work in a professional and friendly environment among outstanding scientists and influential experts.

Eligibility criteria:

Formal criteria:

• competencies to perform specific tasks in a research project (70% of the final score)
• publication and scientific achievement track record, including publications in renowned scientific papers/ magazines (30% of the final score).

Selection process:

Please submit your documents: krzysztof.grzymajlo@upwr.edu.pl
Application deadline: 30.06.2022
Competition results announced: 30.07.2022
Date of project commencement: 01.10.2022

Competition committee:

• Krzysztof Grzymajło, Ph.D. - Chair of the Committee
• Aleksandra Pawlak, Ph.D. – Member of the Committee
• Liliana Kiczak, Ph.D. – Member of the Committee

After reviewing applications, the highest-ranked candidates may be invited for an interview.

Additional information:

This offer is accompanied by a scholarship competition under the aegis of the National Science CenterSONATA BIS project number 2020/38/E/NZ6/00182, "Host-pathogen-microbiota interactions at the first stages of Salmonella enterica infection”, under the supervision of dr hab. Krzysztof Grzymajło, PI.

Description of the research project:

Salmonella infections are one of the most important epidemiological issues worldwide, affecting directly about 200 million people globally, as well as a serious economic problem with an estimated cost as high as 3 billion euros per year only in European Union. Salmonella, a food, and water-born Gram-negative bacterial pathogen, includes more than 2600 serovars infecting many animal species, from reptiles to birds and mammals. Salmonella infection depends on its initial stages – adhesion followed by the invasion of host cells. Among the number of adhesive structures, type 1 fimbriae (T1F) are one of the most extensively studied. T1F are relatively long, rod-shaped structures composed primarily of FimA monomers with a lectin-like FimH protein present at the tip, directly responsible for binding to host cells. Based on the ability to binding high mannose structures frequently present at the host cells surface proteins, there are four major T1F phenotypes investigated to date: 1) high-binding; 2) low-binding; 3) non-binding and 4) no T1F production. What is more, our preliminary studies show that single nucleotide polymorphism (SNP) of the fimH gene in the S. Typhimurium SL1344 genome is directly connected with those phenotypes. The majority of work regarding the first stages of Salmonella infection is focused on direct interaction with host cells, like enterocytes, M-cells, or macrophages, in many cases with the use of immortalized cell lines models. However, colonization of the gastrointestinal tract by enteric pathogens always occurs in a broader context, strongly determined by host-specific gut microflora, which can impact host-pathogen interactions. The gastrointestinal tract is occupied by billions of microbes which can act as a physical barrier against invading bacteria by blocking pathogen access to the epithelial layer. Therefore, a complete infection model should include interactions between the host, its microbiota, and infecting pathogen, which define a specific triangle of interactions. The proposed research aims to investigate the role of Salmonella T1F in the light of the interaction between Salmonella, the intestinal microbiota, and the host during the first stages of infection. The Salmonella infection process can be affected by additional, non-pathogenic microbes called probiotics, which can have a beneficial effect on the host health. Therefore, the second major goal is to enhance microflora ability to stop or limit Salmonella infection at its initial stages by enhancing its adhesion properties. To achieve those goals, we are going to approach several different infection strategies on both in vitro and in vivo models, including 2D cultures of intestinal epithelial cell lines, 3D cultures of apical-out intestinal enteroids, up to two mice models with different Salmonella susceptibility. First, S. Enteritidis and S. Choleraesuis mutants with different T1F phenotypes will be generated. Later, we will investigate the adhesion and invasion abilities of Salmonella mutants as well as the host innate immune response using the abovementioned infection models, in the presence and absence of human and mice intestinal microbiota profiled by 16S rRNA sequencing. This will be followed by mice infection experiments, in which we will profile the microbiome of mice infected by Salmonella with different T1F phenotypes, measure bacterial loads in feces and infected organs, and compare streptomycin pretreatment and natural infection models. Finally, we are planning to generate E. coli Nissle 1917 and Lactobacillus casei probiotic strains with increased adhesion abilities and investigate its impact on the course of Salmonella infection using in vitro and in vivo models. The last includes supplementation of natural microflora with modified probiotics as well as feces transplantation models. Based on our preliminary studies, we hypothesize that T1F phenotypes can affect Salmonella infection outcomes and affect microbiota composition. Using Salmonella mutants with different host-specificity we are planning to explain the role of various T1F phenotypes in Salmonella infection in the context of the host-pathogen-microbiota triangle. Proposed models allow to investigate the pathogenesis of localized and systemic infection by Salmonella thereby fostering the development of new strategies to prevent or treat infection at an early stage of the disease.