Bacteriophages as pathogens and immune modulators?

Area of Science:

• Microbiology
• Molecular Biology
• Pathophysiology

Background:

• Shiga toxins (Stx) are critical virulence factors in enterohemorrhagic Escherichia coli (EHEC) infections.
• The dissemination of Stx from the gastrointestinal tract to target organs like the kidneys and brain is not fully understood.
• Current theories propose Stx is transported by peripheral blood cells to endothelial cells expressing globotriaosylceramide (Gb3) receptors, causing microvascular damage.

Purpose of the Study:

• To investigate alternative mechanisms of Stx dissemination beyond traditional cell-to-cell transfer.
• To explore the potential for prokaryotic genetic material, specifically Stx sequences, to be expressed in eukaryotic cells.
• To consider the broader implications for understanding bacterial pathogenesis and developing novel therapeutic strategies.

Main Methods:

• A study involving high-pressure injection of a plasmid encoding the prokaryotic Stx2 sequence into mice.
• Observation of mortality, pathological indicators of Stx activity, and antibody responses in the injected mice.

Main Results:

• Mice injected with the Stx2 plasmid exhibited mortality and pathology consistent with active Stx toxicity.
• The results suggest that prokaryotic DNA sequences can be taken up by eukaryotic cells, transcribed, and translated into functional proteins.
• Shiga toxin genes are carried on bacteriophage genomes integrated into EHEC.

Conclusions:

• Bacteriophage sequences, including those encoding Stx, may be expressed in eukaryotic cells following EHEC infection.
• This challenges current understandings of bacterial disease mechanisms and toxin dissemination.
• Novel interventions targeting bacteriophages could be a promising therapeutic avenue.