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Changes in membrane fluid state and heat shock response cause attenuation of virulence

Amalia Porta1, Annamaria Eletto, Zsolt Török

  • 1University of Salerno, Department of Pharmaceutical Sciences, Faculty of Pharmacy, Division of BioMedicine, Salerno, Italy.

Journal of Bacteriology
|February 9, 2010
PubMed

Insights

Genetic modification of membrane physical state (MPS) attenuates pathogens like Histoplasma capsulatum. This novel method impairs heat shock response, reduces virulence, and offers potential for new vaccine development.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Immunology

Background:

  • Pathogen attenuation is crucial for controlling infectious diseases.
  • Traditional methods include chemical or heat treatment; recent advances involve genetic modification for live attenuated strains.
  • The heat shock response in various organisms is regulated by the membrane physical state (MPS).

Purpose of the Study:

  • To investigate if modifying the MPS through genetic engineering can attenuate the human fungal pathogen Histoplasma capsulatum.
  • To assess the impact of MPS modification on H. capsulatum's virulence and heat shock response within macrophages.
  • To evaluate the potential of this approach for developing novel vaccines.

Main Methods:

  • Overexpression of a Delta(9)-desaturase gene in the virulent G217B strain of H. capsulatum.
  • Assessment of H. capsulatum survival and persistence within murine macrophages (MPhi).
  • Evaluation of the heat shock response in the modified fungal strain.
  • Testing the attenuated strain's virulence in a mouse model and assessing protection against subsequent challenge with the virulent strain.

Main Results:

  • Overexpression of Delta(9)-desaturase in H. capsulatum led to impaired survival and persistence within murine MPhi.
  • The genetic modification also resulted in the impairment of the heat shock response in the fungal pathogen.
  • The attenuated H. capsulatum strain showed no disease in a mouse model and conferred protection against the virulent parental strain upon challenge.

Conclusions:

  • Genetic modification of the MPS is a viable strategy for attenuating the virulence of intracellular pathogens, demonstrated in both prokaryotes and eukaryotes.
  • This approach offers a new method for generating attenuated pathogens and may lead to a novel class of vaccines targeting membrane fluid state and stress response.
  • The study highlights the conserved role of MPS in regulating pathogen stress response and virulence across evolutionarily distant organisms.

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