Biology subjects

Urbanova, V.

Publications and source records attributed to Urbanova, V..

3 recordsLinked to original sources

bioRxiv2026

Host-derived lipids license proliferation of sterol-auxotrophic tick cells and promote flavivirus output

Sterol molecules play indispensable roles in the biology of cells and organisms. Yet, arthropods, including ticks, lack the capacity for de novo sterol biosynthesis and must rely on exogenous sources. How these organisms sense and utilise exogenous lipids at the cellular level remains poorly understood. Here, we show that host cholesterol and linoleic acid act as essential external signals that license proliferation of Ixodes ricinus tick cells. In lipid-depleted conditions, cells fail to proliferate despite retaining intracellular cholesterol, indicating that exogenous lipids function as regulatory cues rather than merely structural components. We further demonstrate that tick cells exhibit a non-canonical intracellular distribution of cholesterol, with predominant accumulation in lysosome-associated compartments, and that lipid availability induces a coordinated transcriptional program involving lipid uptake and trafficking machinery. Importantly, we find that limiting host lipid availability significantly reduces extracellular RNA output of tick-borne encephalitis virus (TBEV) from infected tick cells, indicating that viral production is affected by the metabolic state of the host cell. Together, our findings establish host-derived lipids as key regulators of cellular state in a sterol-auxotrophic organism and identify lipid availability as a determinant of flavivirus output. This work provides a conceptual framework linking nutrient sensing, cell proliferation, and vector-pathogen interactions.

microbiology↗

bioRxiv2026

The Bacterial Kinase AnmK Integrates into Tick Genome and Biology

Horizontal Gene Transfer (HGT) contributes to eukaryotic evolution, potentially bringing phenotypic novelties to the recipient organisms. Ticks pose a severe threat to human health as vectors of various pathogens, including viruses, bacteria and protozoa, while stably hosting endosymbiotic bacteria. As such, these obligate blood-feeding parasites have been and continue to be exposed to HGT from a broad range of donors. To determine whether bacterial-to-tick HGT has contributed to important tick traits, we surveyed Ixodes tick genomes for HGT events. We revealed duplications of the known bacteria-derived gene dae2 and discovered two novel cases of bacterial HGT, the most remarkable of which involves a bacterial peptidoglycan metabolic gene (anmK) acquired by the common ancestor of ticks. The acquisition of an intron demonstrates "eukaryotization" of anmK within tick genomes. Transcript profiling revealed that anmK expression is upregulated during blood feeding, peaking in female ovaries, a niche occupied by horizontally acquired endosymbionts. Biochemical analysis confirmed that, to some extent, recombinant AnmK retains kinase activity on its cognate substrate - the bacterial cell wall component 1,6-anhydro-N-acetylmuramic acid. Immunolocalization showed that the enzyme is predominantly localized towards outer layers of the vitellogenic oocytes. Silencing of anmK in different tick species compromised blood-feeding and reproduction, demonstrating that this domesticated bacterial enzyme underpins reproductive fitness across tick species. Our findings exemplify the ability of horizontally acquired genes to integrate into the host biology and thereby shape host life history.

evolutionary biology↗

bioRxiv2018

Tracking Borrelia afzelii from infected Ixodes ricinus nymphs to mice suggests a direct ‘gut-to-mouth’ route of Lyme disease transmission

Quantitative tracking of Borrelia afzelii has shown that its transmission cycle differs from the salivary route of B. burgdorferi transmission by Ixodes scapularis. Borrelia afzelii are abundant in the guts of unfed Ixodes ricinus nymphs and their numbers continuously decrease during feeding. In contrast, spirochetes are not present in the salivary glands. Borrelia afzelii transmission starts during the early stages of feeding, spirochetes could be detected in murine skin within 1 day of tick attachment. Tick saliva is not essential for B. afzelii infectivity, the main requirement for successful host colonization being a change in outer surface protein expression that occurs in the tick gut during feeding. Spirochetes in vertebrate mode are able to survive within the host even if the tick is not present. On the basis of our data we propose that a direct gut-to-mouth route of infection appears to be the main route of B. afzelii transmission.\n\nImportanceLyme borreliosis is the most common vector-borne disease in the USA and Europe. The disease is caused by the Borrelia spirochetes and is transmitted through Ixodes ticks. A better understanding of how Borrelia spirochetes are transmitted is crucial for development of efficient vaccines for preventing Lyme borreliosis. Here we present that the transmission of European B. afzelii spirochetes by I. ricinus ticks significantly differs from the model transmission cycle described for American B. burgdorferi/I. scapularis. We suggest that B. afzelii is not transmitted via salivary glands but most likely through the midgut to mouthpart route. We further demonstrate that tick saliva is not important for B. afzelii transmission and infectivity. Therefore, we support early studies by Willy Burgdorfer, who proposed that Borrelia transmission occurs by regurgitation of infected gut contents. Our findings collectively point to the Borrelia-tick midgut interface as the correct target in our endeavours to combat Lyme borreliosis.

microbiology↗