Different strains of same bacteria trigger widely varying immune responses

January 11, 2018, Public Library of Science
Scanning electron micrograph of S. aureus bacteria escaping destruction by human white blood cells. Credit: NIAID via Flickr

Genetic differences between different strains of the same pathogenic bacterial species appear to result in widely varying immune system responses, according to new research published in PLOS Pathogens.

Previous research has found that different people vary in their susceptibility to infection with the same of pathogenic bacteria. Individual in people's immune systems may explain this variability, but differences between could play a role, too.

To better understand this role, Uri Sela of The Rockefeller University, New York, and colleagues 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 responded after exposure to different strains of each species.

The researchers found that, in blood from a single person, different strains of each species produced widely varied responses by T and B cells of the adaptive immune system—the portion of the immune system responsible for creating "memory" of specific pathogens to protect against future infection. The same distinct responses to different strains were seen in blood samples from 10 additional donors.

Next, the research team 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 triggered a dampened T cell response, suggesting that differences in "accessory" genes were responsible for the varied responses seen for unmutated .

These findings suggest that differences in bacterial "accessory" genes—not just differences between people—may help explain the clinical variation generally found among patients infected with the same bacterial species.

Previous research has often described "signature" immune responses to different bacteria using only a single strain for each species. However, based on findings of the current study, the researchers propose that immune response signatures should instead be defined according to the specific strain or the species' common "core genome." Such a shift could aid development of strategies for predicting disease outcomes in patients.

"The current practice with infected patient is to only identify the bacterial species," the authors elaborate. "Our findings raise the possibility that in the future we might need to define the specific infecting strain as part of the patient evaluation and treatment."

Explore further: Immune response to bacteria—distinguishing helpers from harmers

More information: Sela U, Euler CW, Correa da Rosa J, Fischetti VA (2018) Strains of bacterial species induce a greatly varied acute adaptive immune response: The contribution of the accessory genome. PLoS Pathog 14(1): e1006726. doi.org/10.1371/journal.ppat.1006726

Related Stories

Immune response to bacteria—distinguishing helpers from harmers

January 10, 2018
Some staphylococcus bacteria live peacefully on human skin and membranes in a mutually beneficial relationship with their host, while others are able to exist far from a human host in soil or in water. When we come into contact ...

Strain-level profiling yields new insights into mother-infant microbiomes

October 18, 2016
Direct microbial sequencing of environmental samples, such as from ocean water, hospital surfaces, and the human gut, have illuminated the vast number of microbes present in our world. However, a microbial species can be ...

Newly discovered viral marker could help predict flu severity in infected patients

October 20, 2017
Flu viruses contain defective genetic material that may activate the immune system in infected patients, and new research published in PLOS Pathogens suggests that lower levels of these molecules could increase flu severity.

Mapping the gut microbiome to better understand its role in obesity

February 14, 2015
Several recent science studies have claimed that the gut microbiome—the diverse array of bacteria that live in the stomach and intestines—may be to blame for obesity. But Katherine Pollard, PhD, a senior investigator ...

Recommended for you

Malaria study reveals gene variants linked to risk of disease

April 25, 2018
Many people of African heritage are protected against malaria by inheriting a particular version of a gene, a large-scale study has shown.

Kids with rare rapid-aging disease get hope from study drug

April 24, 2018
Children with a rare, incurable disease that causes rapid aging and early death may live longer if treated with an experimental drug first developed for cancer patients, a study suggests.

Commonly prescribed heartburn drug linked to pneumonia in older adults

April 24, 2018
Researchers at the University of Exeter have found a statistical link between pneumonia in older people and a group of medicines commonly used to neutralise stomach acid in people with heartburn or stomach ulcers. Although ...

Early treatment for leg ulcers gets patients back on their feet

April 24, 2018
Treating leg ulcers within two weeks by closing faulty veins improves healing by 12 per cent compared to standard treatment, according to new findings.

Research finds new mechanism that can cause the spread of deadly infection

April 20, 2018
Scientists at the University of Birmingham have discovered a unique mechanism that drives the spread of a deadly infection.

Selection of a pyrethroid metabolic enzyme CYP9K1 by malaria control activities

April 20, 2018
Researchers from LSTM, with partners from a number of international institutions, have shown the rapid selection of a novel P450 enzyme leading to insecticide resistance in a major malaria vector.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.