Neisseria meningitidis filamentous phage MDA promotes colonisation by selecting hyperadhesive pili variants

Area of Science:

• Microbiology
• Virology
• Bacterial Pathogenesis

Background:

• Filamentous phages are non-lytic viruses that can benefit their bacterial hosts.
• In Neisseria meningitidis, the MDA phage is linked to invasive diseases via biofilm formation during epithelial colonization.
• Existing models show filamentous phages binding to bacterial pili tips for entry.

Purpose of the Study:

• To investigate the interaction between filamentous phage MDA and type IV pili in Neisseria meningitidis.
• To understand how phage infection influences bacterial adhesion and colonization.

Main Methods:

• Utilized Neisseria meningitidis and bacteriophage MDA as model organisms.
• Analyzed phage binding patterns to type IV pili variants.
• Assessed the correlation between pilin charge, bacterial adhesion, and phage infection.
• Studied the amplification of phage-positive populations upon adhesion to human cells.

Main Results:

• MDA phage binds along the entire length of type IV pili, with a preference for positively charged pilin variants.
• Bacteria expressing more positively charged pilin exhibit higher adhesion to human cells.
• MDA phage preferentially targets and amplifies the most adhesive bacterial variants.
• Adhesion to human cells is sufficient to increase the population of phage-infected meningococci.

Conclusions:

• Filamentous phage MDA employs antigenic variation in type IV pili for host targeting.
• The phage selects for hyperadhesive bacterial strains, linking phage infection to enhanced colonization.
• This mechanism highlights a strategy where phages promote the success of their bacterial hosts in colonizing human cells.