Research Report 2010 2011 - Helmholtz-Zentrum für ...

SCIENTIFIC REPORTS | Infection and Immunity | Host Pathogen Interactions
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02 Host Pathogen Interactions
TOPIC SPEAKER | Prof. Dr. Klaus Schughart | Department of Infection Genetics | kls@helmholtz-hzi.de
The severity of an infectious disease is determined by the intricate interactions between pathogen and host. Many studies have
been performed to identify specifi c virulence factors in individual pathogenic microbe species but our knowledge about important
factors in the host is still very limited. For example, genetic and environmental factors are crucially involved in the host response
and determine favorable or unfavorable disease outcomes. Also very little is known about bacterial communities in the host and
how they may infl uence the activities of pathogenic microbes or the host response. Furthermore, pathogens that are able to cross
the species barrier represent a constant threat to the human population. Here, not much is known about the molecular mechanisms
of host adaptation.
Therefore, the objective of this topic is to obtain a better understanding about the complexity of the interactions between the host
and and infectious pathogens. The different research projects aim to identify host factors which infl uence its susceptibility and
resistance to infections, to unravel mechanisms of cross-species transmission, and to characterize microbial communities and
how they may modulate the host response to pathogens. To achieve these goals, the topic will perform research projects in the
following areas.
Microbial communities in the host and their relevance for infectious diseases
In the oral cavity approximately 500 bacterial species have been identifi ed so far. Many of these bacteria are able to form biofi l m s ,
so called dental plaque. In order to form biofi lms, bacterial species must communicate with each other. We are, therefore, studying
the molecular basis of bacterial communication pathways and investigate possible ways to disrupt them.
In cystic fi brosis (CF) patients, Pseudomonas aeruginosa is the most dominant bacterial pathogen causing chronic lung disease.
However, P. aeruginosa isolates from patients revealed that they do not represent a single variant but rather different phenotypes.
And the presence of different phenotypes has been correlated with poor prognosis in CF patients. To better understand the underlying
biological and molecular mechanisms of phenotype changes, we will study the diversity of bacterial communities and isolates
in CF patients.
Biofi lms play an important role in the establishment of pathogenic bacterial colonistaion in the host. Very little is known so far
about pathogenic communities in biofi lms and the relationship between the biodiversity and pathogenicity in presumed sterile
environments of the host. We are thus determining the biodiversity in biofi lms from patient material like pacemakers, bone and
dental implants. With the knowledge which bacterial communities live at the different niches in the human body new approaches to
control or prevent biofilms and to optimize their biodiversity with regards to the control of pathogenic bacteria are being developed.
The nasal cavity and the gastro-intestinal tract harbor a huge number of bacterial organisms which may be advantageous or, in
some cases, pathogenic to the host. We are, therefore, aiming to defi ne the conditions which favor or exclude the colonization with
pathogenic bacteria. A special focus is the colonization of the nose with multi-resistant Staphylococcus aureus and its interaction
with other community members.