Novel modelling approaches to predict the role of antivirals in reducing influenza transmission.

To aid understanding of the effect of antiviral treatment on population-level influenza transmission, we used a novel pharmacokinetic-viral kinetic transmission model to test the correlation between nasal viral load and infectiousness, and to evaluate the impact that timing of treatment with the antivirals oseltamivir or baloxavir has on influenza transmission. The model was run under three candidate profiles whereby infectiousness was assumed to be proportional to viral titer on a natural-scale, log-scale, or dose-response model. Viral kinetic profiles in the presence and absence of antiviral treatment were compared for each individual (N = 1000 simulated individuals); subsequently, viral transmission mitigation was calculated. The predicted transmission mitigation was greater with earlier administration of antiviral treatment, and with baloxavir versus oseltamivir. When treatment was initiated 12-24 hours post symptom onset, the predicted transmission mitigation was 39.9-56.4% for baloxavir and 26.6-38.3% for oseltamivir depending on the infectiousness profile. When treatment was initiated 36-48 hours post symptom onset, the predicted transmission mitigation decreased to 0.8-28.3% for baloxavir and 0.8-19.9% for oseltamivir. Model estimates were compared with clinical data from the BLOCKSTONE post-exposure prophylaxis study, which indicated the log-scale model for infectiousness best fit the observed data and that baloxavir affords greater reductions in secondary case rates compared with neuraminidase inhibitors. These findings suggest a role for baloxavir and oseltamivir in reducing influenza transmission when treatment is initiated within 48 hours of symptom onset in the index patient.

The interaction of cofilin with the actin filament.

Cofilin is a key actin-binding protein that is critical for controlling the assembly of actin within the cell. Here, we present the results of molecular docking and dynamics studies using a muscle actin filament and human cofilin I. Guided by extensive mutagenesis results and other biophysical and structural studies, we arrive at a model for cofilin bound to the actin filament. This predicted structure agrees very well with electron microscopy results for cofilin-decorated filaments, provides molecular insight into how the known F- and G-actin sites on cofilin interact with the filament, and also suggests new interaction sites that may play a role in cofilin binding. The resulting atomic-scale model also helps us understand the molecular function and regulation of cofilin and provides testable data for future experimental and simulation work.