Biology subjects

Planet, P.

Publications and source records attributed to Planet, P..

6 recordsLinked to original sources

bioRxiv2022

Pre-epidemic evolution of the USA300 clade and a molecular key for classification

USA300 has remained the dominant community and healthcare associated methicillin-resistant Staphylococcus aureus (MRSA) clone in the United States and in northern South America for at least the past 20 years. In this time, it has experienced epidemic spread in both of these locations. However, its pre-epidemic evolutionary history and origins are incompletely understood. Large sequencing databases, such as NCBI, PATRIC, and Staphopia, contain clues to the early evolution of USA300 in the form of sequenced genomes of USA300 isolates that are representative of lineages that diverged prior to the establishment of the South American (SAE) and North American (NAE) epidemics. In addition, historical isolates collected prior to the emergence of epidemics can help reconstruct early events in the history of this lineage. Here, we take advantage of the accrued, publicly available data, as well as two newly sequenced pre-epidemic historical isolates from 1996, and a very early diverging ACME-negative NAE genome to understand the pre-epidemic evolution of USA300. We use database mining techniques to emphasize genomes similar to pre-epidemic isolates, with the goal of reconstructing the early molecular evolution of the USA300 lineage. Phylogenetic analysis with these genomes confirms that the North American Epidemic and South American Epidemic USA300 lineages diverged from a most recent common ancestor around 1970 with high confidence, and it also pinpoints the independent acquisition events of the of the ACME and COMER loci with greater precision than in previous studies. We solidify evidence for a North American origin of the USA300 lineage and identify multiple introductions of USA300 into South America from North America. Notably, we describe a third major USA300 clade (the pre-epidemic branching clade; PEB1) consisting of both MSSA and MRSA isolates circulating around the world that diverged from the USA300 lineage prior to the establishment of the South American and North American epidemics. We present a detailed analysis of specific sequence characteristics of each of the major clades, and present diagnostic positions that can be used to classify new genomes.

genomics↗

bioRxiv2022

Efficient Pangenome Construction through Alignment-Free Residue Pangenome Analysis (ARPA)

Protein sequences can be transformed into vectors composed of counts for each amino acid (vector of Residue Counts; vRC) that are mathematically tractable and retain information about homology. We use vRCs to perform alignment-free, residue-based, pangenome analysis (ARPA; https://github.com/Arnavlal/ARPA). ARPA is 70-90 times faster at identifying homologous gene clusters compared to standard techniques, and offers rapid calculation, visualization, and novel phylogenetic approaches for pangenomes.

bioinformatics↗

bioRxiv2020

Emerging SARS-CoV-2 diversity revealed by rapid whole genome sequence typing.

BackgroundDiscrete classification of SARS-CoV-2 viral genotypes can identify emerging strains and detect geographic spread, viral diversity, and transmission events. MethodsWe developed a tool (GNUVID) that integrates whole genome multilocus sequence typing and a supervised machine learning random forest-based classifier. We used GNUVID to assign sequence type (ST) profiles to each of 69,686 SARS-CoV-2 complete, high-quality genomes available from GISAID as of October 20th 2020. STs were then clustered into clonal complexes (CCs), and then used to train a machine learning classifier. We used this tool to detect potential introduction and exportation events, and to estimate effective viral diversity across locations and over time in 16 US states. ResultsGNUVID is a scalable tool for viral genotype classification (available at https://github.com/ahmedmagds/GNUVID) that can be used to quickly process tens of thousands of genomes. Our genotyping ST/CC analysis uncovered dynamic local changes in ST/CC prevalence and diversity with multiple replacement events in different states. We detected an average of 20.6 putative introductions and 7.5 exportations for each state. Effective viral diversity dropped in all states as shelter-in-place travel-restrictions went into effect and increased as restrictions were lifted. Interestingly, our analysis showed correlation between effective diversity and the date that state-wide mask mandates were imposed. ConclusionsOur classification tool uncovered multiple introduction and exportation events, as well as waves of expansion and replacement of SARS-CoV-2 genotypes in different states. Combined with future genomic sampling the GNUVID system could be used to track circulating viral diversity and identify emerging clones and hotspots.

genomics↗

bioRxiv2020

Rapid whole genome sequence typing reveals multiple waves of SARS-CoV-2 spread

As the pandemic SARS-CoV-2 virus has spread globally its genome has diversified to an extent that distinct clones can now be recognized, tracked, and traced. Identifying clonal groups allows for assessment of geographic spread, transmission events, and identification of new or emerging strains that may be more virulent or more transmissible. Here we present a rapid, whole genome, allele-based method (GNUVID) for assigning sequence types to sequenced isolates of SARS-CoV-2 sequences. This sequence typing scheme can be updated with new genomic information extremely rapidly, making our technique continually adaptable as databases grow. We show that our method is consistent with phylogeny and recovers waves of expansion and replacement of sequence types/clonal complexes in different geographical locations. GNUVID is available as a command line application (https://github.com/ahmedmagds/GNUVID).

genomics↗

bioRxiv2019

Genomic epidemiology of vancomycin 1 resistant Enterococcus faecium (VREfm) in Latin America: Revisiting the global VRE population structure

The prevalence of vancomycin-resistant Enterococcus faecium varies across geographical regions yet little is known about its population structure in Latin America. Here, we provide a complete genomic characterization of 55 representative Latin American VREfm recovered from 1998-2015 in 5 countries. We found that VREfm population in the region is structured into two main clinical clades without geographical clustering. To place our regional findings in context, we reconstructed the global population structure of VREfm by including 285 genomes from 36 countries from 1946-2017. Our results differ from previous studies showing an early branching of animal related isolates and a further split of clinical isolates into two sub-clades, all within clade A. The overall phylogenomic structure was highly dependent on recombination (54% of the genome) and the split between clades A and B is estimated to have occurred more than 3585 years BP. Furthermore, while the branching of animal isolates and clinical clades was predicted to have occur [~]894 years BP, our molecular clock calculations suggest that the split within the clinical clade occurred around [~]371 years BP. By including isolates from Latin America, we present novel insights into the population structure of VREfm and revisit the evolution of this pathogen.

microbiology↗

bioRxiv2018

Mobile genetic element-encoded hypertolerance to copper protects Staphylococcus aureus from killing by host phagocytes

Pathogens are exposed to toxic levels of copper during infection and copper tolerance may be a general virulence mechanism used by bacteria to resist host defences. In support of this, inactivation of copper-exporter genes has been found to reduce the virulence of bacterial pathogens in vivo. Here we investigate the role of copper-hypertolerance in methicillin resistant Staphylococcus aureus. We show that a copper-hypertolerance locus (copB-mco), carried on a mobile genetic element, is prevalent in a collection of invasive S. aureus strains and more widely among clonal complex 22, 30 and 398 strains. The copB and mco genes encode a copper efflux pump and a multicopper oxidase, respectively. Isogenic mutants lacking copB or mco had impaired growth in subinhibitory concentrations of copper. Transfer of a copB-mco encoding plasmid to a naive clinical isolate resulted in a gain of copper hypertolerance and enhanced bacterial survival inside primed macrophages. The copB and mco genes were upregulated within infected macrophages and their expression was dependent on the copper sensitive operon repressor CsoR. Isogenic copB and mco mutants were impaired in their ability to persist intracellularly in macrophages and were less resistant to phagocytic killing in human blood than the parent strain. The importance of copper-regulated genes in resistance to phagocytic killing was further elaborated using mutants expressing a copper-insensitive variant of CsoR. Our findings suggest that the gain of mobile genetic elements carrying copper-hypertolerance genes contributes to the evolution of virulent strains of S. aureus, better equipped to resist killing by host immune cells.

microbiology↗