Kende, J. | Search bioRxiv

bioRxiv2025

Fluke-borne viruses are a risk factor for diseases caused by carcinogenic trematodes

Three trematode parasites, Schistosoma haematobium, Opisthorchis viverrini, and Clonorchis sinensis are recognized group 1 carcinogens for their roles in squamous cell carcinoma of the urinary bladder and bile duct cancer (cholangiocarcinoma). We aimed to assess the presence of fluke viruses and their association with malignancy in fluke infections. We showed that all three carcinogenic trematodes harbored related viruses. Focusing on O. viverrini, we observed virus persistence at discrete life stages and viral tropism for the fluke tegument, and we provided molecular and serological evidence of parasitized hosts exposure to viral RNA and proteins. Serological analyses confirmed seroconversion of residents in endemic sites and revealed that antibody titers and avidity against fluke-borne viruses increase in individuals with hepatobiliary diseases. Random forest models discriminated efficiently between liver-fluke-infected participants without disease and those with periductal fibrosis or cholangiocarcinoma. Thus, we show that fluke-borne viruses are risk factors and diagnostic targets for fluke-associated cancer.

microbiology↗

bioRxiv2025

The phylodynamic threshold of measurably evolving populations

The molecular clock is a fundamental tool for understanding the time and pace of evolution, requiring calibration information alongside molecular data. Sampling times are often used for calibration since some organisms accumulate enough mutations over the course of their sampling period. This practice ties together two key concepts: measurably evolving populations and the phylodynamic threshold. Our current understanding suggests that populations meeting these criteria are suitable for molecular clock calibration via sampling times. However, the definitions and implications of these concepts remain unclear. Using Hepatitis B virus-like simulations and analyses of empirical data, this study shows that determining whether a population is measurably evolving or has reached the phylodynamic threshold does not only depend on the data, but also on model assumptions and sampling strategies. In Bayesian applications, a lack of temporal signal due to a narrow sampling window results in a prior that is overly informative relative to the data, such that a prior that is potentially misleading typically requires a wider sampling window than one that is reasonable. In our analyses we demonstrate that assessing prior sensitivity is more important than the outcome of tests of temporal signal. Our results offer guidelines to improve molecular clock inferences and highlight limitations in molecular sequence sampling procedures.

bioinformatics↗