Biology subjects

Hudson, P.

Publications and source records attributed to Hudson, P..

3 recordsLinked to original sources

bioRxiv2023

Periodic shifts in viral load increase risk of spillover from bats

Prediction and management of zoonotic pathogen spillover requires an understanding of infection dynamics within reservoir host populations. Transmission risk is often assessed using prevalence of infected hosts, with infection status based on the presence of genomic material. However, detection of viral genomic material alone does not necessarily indicate the presence of infectious virus, which could decouple prevalence from transmission risk. We undertook a multi-faceted investigation of Hendra virus shedding in Pteropus bats, combining insights from virus isolation, viral load proxies, viral prevalence, and longitudinal patterns of shedding, from 6,151 samples. In addition to seasonal and interannual fluctuation in prevalence, we found evidence for periodic shifts in the distribution of viral loads. The proportion of bats shedding high viral loads was higher during peak prevalence periods during which spillover events were observed, and lower during non-peak periods when there were no spillovers. We suggest that prolonged periods of low viral load and low prevalence reflect prolonged shedding of non-infectious RNA, or viral loads that are insufficient or unlikely to overcome dose barriers to spillover infection. These findings show that incorporating viral load (or proxies of viral load) into longitudinal studies of virus excretion will better inform predictions of spillover risk than prevalence alone. Significance statementWe present a comprehensive analysis of a high-profile bat-virus system (Hendra virus in Australian flying-foxes) to demonstrate that both prevalence and viral loads can shift systematically over time, resulting in concentrated periods of increased spillover risk when prevalence and viral loads are high. We further suggest that prolonged periods of low-prevalence, low-load shedding may not reflect excretion of infectious virus, resolving the outstanding puzzle of why spillovers have not been observed during periods of low off-season prevalence in subtropical Australia, or more frequently in tropical Australia despite consistent low-prevalence shedding. The consideration of viral loads (or proxies of viral load) along with prevalence may improve risk inference from longitudinal surveys of zoonotic viruses across wildlife reservoir hosts.

ecology↗

bioRxiv2020

Pesticide-induced Alterations to Phytoplankton Abundance and Community Structure Alter Ecosystem Respiration: Implications for the Carbon Cycle?

AO_SCPLOWBSTRACTC_SCPLOWCurrent predictions of the effects of synthetic chemicals on freshwater ecosystems are hampered by the sheer number of chemical contaminants entering aquatic systems, the diversity of organisms inhabiting these systems, and uncertainties about how contaminants alter ecosystem metabolism. We conducted a mesocosm experiment that elucidated the responses of ponds composed of phytoplankton and zooplankton to standardized concentrations of 12 pesticides, nested within four pesticide classes and two pesticide types. We show that the effects of the pesticides on algae were consistent within herbicides and insecticides and responses of over 70 phytoplankton species and genera were consistent within broad taxonomic groups. Insecticides generated top-down effects on phytoplankton community composition and abundance, which were associated with persistent increases in ecosystem respiration. Herbicides reduced phytoplankton abundance, which was associated with decreases in primary productivity and ecosystem respiration. These results suggest that widespread pesticide use could have underexplored implications for the global carbon cycle. While these effects on ecosystem respiration were mediated through complex effects on communities, taxonomic groups of organisms responded similarly to pesticide types, suggesting opportunities to simplify ecological risk assessment.

ecology↗

bioRxiv2020

Consistent Effects of Pesticides on Community Structure and Ecosystem Function in Freshwater Systems

AO_SCPLOWBSTRACTC_SCPLOWPredicting ecological effects of contaminants remains challenging because of the sheer number of chemicals and their ambiguous role in biodiversity-ecosystem function relationships. We evaluated responses of pond ecosystems to standardized concentrations of 12 pesticides, nested in four pesticide classes and two pesticide types. We show consistent effects of herbicides and insecticides on ecosystem function, but slightly less consistent effects on community composition. Effects of pesticides on ecosystem functions were often mediated by changes to biodiversity, and our analyses show that consistency in effects of pesticide types on functions was driven by functional redundancy among species. These results suggest that risk assessment of the thousands of registered chemicals on ecosystem responses could be simplified to a smaller number of chemical groups and to groups of functionally redundant taxa.

ecology↗