Biology subjects

Munoz-Leal, S.

Publications and source records attributed to Munoz-Leal, S..

2 recordsLinked to original sources

bioRxiv2025

Evolution and comparative genomics of tick-associated endosymbionts: insights into metabolic pathways and historical biogeographic patterns

AbstractTicks (Ixodida) are the second most important vectors of infectious diseases in vertebrates, after mosquitoes. They also maintain mutualistic relationships with bacteria, such as endosymbionts that provide essential B vitamins absent in their blood diet. The most studied endosymbionts belong to the genera Coxiella, Midichloria, and Francisella. Francisella includes endosymbionts (FE), pathogens (FP), putative intermediates (FI), and free-living (FL) strains, making them valuable for evolutionary and comparative genomics. In this study, total DNA from six adult female ticks of the genera Hyalomma and Amblyomma was sequenced to obtain new FE genomes. Additionally, two deep metagenomes from public data were assembled, resulting in a dataset of 22 Francisella strains. This dataset was used to reconstruct a phylogenomic framework and compare vitamin biosynthesis and virulence pathways. An MLST-based dense phylogeny was also built to explore biogeographic patterns. The resulting phylogenomic tree shows FE form a monophyletic group derived from FP, possibly due to historical biogeography or recent horizontal transfers. Comparative analyses reveal that FE retain key metabolic pathways while losing nonessential ones, reflecting a selective genome reduction. These results advance our understanding of symbiont evolution in a changing world, revealing molecular adaptations that underpin tick- symbiont relationships and offering genomic insights with potential applications for disease control.

evolutionary biology↗

bioRxiv2020

Ticks convert pathogenic Coxiella into endosymbionts

Both symbiotic and pathogenic bacteria in the family Coxiellaceae cause morbidity and mortality in humans and animals. For instance, Coxiella-like endosymbionts (CLEs) improve the reproductive success of ticks -- a major disease vector, while Coxiella burnetii is the etiological agent of human Q fever and uncharacterized coxiellae cause infections in both animals and humans. To better understand the evolution of pathogenesis and symbiosis in this group of intracellular bacteria, we sequenced the genome of a CLE present in the soft tick Ornithodoros amblus (CLEOA) and compared it to the genomes of other bacteria in the order Legionellales. Our analyses confirmed that CLEOA is more closely related to C. burnetii, the human pathogen, than to CLEs in hard ticks, and showed that most clades of CLEs contain both endosymbionts and pathogens, indicating that several CLE lineages have evolved independently from pathogenic Coxiella. We also determined that the last common ancestor of CLEOA and C. burnetii was equipped to infect macrophages, and that even though HGT contributed significantly to the evolution of C. burnetii, most acquisition events occurred primarily in ancestors predating the CLEOA-C. burnetii divergence. These discoveries clarify the evolution of C. burnetii, which previously was assumed to have emerged when an avirulent tick endosymbiont recently gained virulence factors via HGT. Finally, we identified several metabolic pathways, including heme biosynthesis, that are likely critical to the intracellular growth of the human pathogen but not the tick symbiont, and show that the use of heme analogs is a promising approach to controlling C. burnetii infections.

microbiology↗