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Bacteria and immune responses

Genetic differences between different strains of the same pathogenic bacterial species appear to result in widely varying immune system responses, it is reported.

Previous research found that people vary in their sensitivity to infection with the same species of pathogenic bacteria. Differences in immune systems may explain the variability, but differences between bacterial strains could also play a role.

The researchers studied different strains of two major species of pathogenic bacteria: Staphylococcus aureus and Streptococcus pyogenes

They tested how immune system T and B cells in donated human blood samples responded after exposure to different strains of each species.

In blood from a single person, they found that different strains of each species produced widely varied responses by T and B cells of the adaptive immune system.

They also created mutant bacteria in which they deactivated “accessory” genes that are responsible for between-strain differences, leaving the “core” genome of the species intact. 

They found that the mutant strains triggered a dampened T cell response, suggesting that differences in “accessory” genes were responsible for the varied responses seen for unmutated strains.

The research was published in PLOS Pathogens.

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