Viral Dynamics of the Respiratory Syncytial Virus During Experimental Human Challenge: Implication for Transmission...

Respiratory syncytial virus (RSV) is a leading cause of respiratory infection. Quantifying its clinical, viral, and immune kinetics could provide further insights into tailoring interventions strategies at both individual and population levels.

We analyzed high-resolution viral, immunological, and clinical data from 225 adults experimentally infected with RSV, using mathematical models to characterize host-pathogen interactions.

The best-fitting model incorporated three main mechanisms: a power-law relationship linking viral RNA to infectious virus, an innate immune response reducing target cell susceptibility and viral production, and an adaptive immune response integrating antibody and non-antibody components. The non-antibody response increased infected cell clearance by 7-fold (90% Prediction Interval [PI], 2-20-fold). Infectious virus was detected 3 days after exposure (90% PI, 2-5 days), and was cleared 8 days after exposure (6-11 days), corresponding to a median shedding duration of 5 days (3.5-10 days). Viral RNA persisted longer, with a median clearance time of 12 days (90% PI, 9-15 days). Symptom occurence was significantly associated with viral dynamics. While paucisymptomatic individuals represented 35% of our population, they accounted for only 5% of infectious viral shedding.

These results provide new insights into RSV infection to inform diagnostics, and prevention strategies.