What is it about?
We compared the genomes of Campylobacter taken from blood and stool, using a machine learning method for identifying functionally important mutations. This method identified several genes involved in cell shape which showed key differences in the burden of important mutations between blood and stool isolates. Examination using cryo-electron microscopy revealed that a number of the blood isolates had changed from being helical, like Campylobacter usually are, to having a rod shape, or an elongated helical shape.
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Why is it important?
This suggests a shift in selective pressures following a move from the gut to the blood. Not all of the strains that carried impactful mutations showed shape changes, and these proteins are known to have other roles, such as the localisation of proteins critical for causing infection, so it's possible that this selective pressure isn't acting on shape, but on another trait. It's unclear whether this change in shape allows these strains to infect new hosts, as helical shape is known to help Campylobacter burrow through gut mucus.
Perspectives
This is a promising indication that this machine learning method correctly identifies mutations of interest and is a good tool for screening genomes for signs of adaptation to a new lifestyle. It also indicates there may be some important genetic differences between invasive and gastrointestinal Campylobacter that warrant further investigation.
Dr Nicole E Wheeler
Wellcome Sanger Institute
Read the Original
This page is a summary of: Genomic correlates of extraintestinal infection are linked with changes in cell morphology in Campylobacter jejuni, Microbial Genomics, February 2019, Society for General Microbiology,
DOI: 10.1099/mgen.0.000251.
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