In PLOS Genetics, a team from Australia, the US, and UK takes a look at the ways insertion sequences are scattered across Shigella genomes, along with the consequences of these insertions within and between the S. dysenteriae, S. sonnei, and S. flexneri species compared to the Escherichia coli species from which they evolved. "Originally classified as a genus due to shared disease features," they say, "Shigella species actually represent distinct lineage of Escherichia coli that have become human-restricted dysentery pathogens via convergent evolution." Using Shigella and E. coli reference genome sequences, along with available sequences for related species and strains, the team put together S. dysenteriae, S. sonnei, and S. flexneri genomes lacking insertion sequences, highlighting five parallel insertion sequence expansions in Shigella.
Researchers from New Zealand, Korea, and other international sites consider host antigen production in the context of Plasmodium vivax malaria parasite genetic diversity for a paper appearing in PLOS Neglected Tropical Diseases. In an effort to track down parasite polymorphisms affecting antibody production in infected hosts, the team used targeted amplicon sequencing to profile genetic diversity for the extracellular, or "ecto," domain of the erythrocyte binding protein (PvEBP) in more than 300 P. vivax clinical isolates collected in eight countries, uncovering apparent ties to antibodies targeting PvEBP in blood samples from individuals infected with P. vivax. "The genetic phenotypes of PvEBP-ecto were classified into four clusters, based on the insertion/deletion variation," the authors report, noting that these indels appear to impact host antibody recognition.
For a paper in PLOS One, a Ghana-led team shares findings from a molecular epidemiological study of cholera-causing Vibrio cholerae strains collected during outbreaks in Ghana between 2012 and 2015. With multi-locus variable-number tandem-repeat analysis, virulence factor analyses, serotyping, antibiotic susceptibility screening, and other approaches, the researchers found that more than 39 percent of the 277 clinical isolates considered from outbreaks in 2012, 2014, and 2015 represented other bacterial species, while 168 isolates represented confirmed V. cholerae infections. Within the latter group, they characterized the most common V. cholerae serotype, tracked down virulence genes in the V. cholerae genotypes detected in the area, and saw pronounced drug resistance in the cholera-causing isolates collected during outbreaks in Ghana in 2014 and 2015.