Fig. 6.

Kinetics of natural infections vs. immunization. Schematics of antigen concentration in the LN as a function of time for natural infections (acute or chronic) and different vaccination technologies. Natural infections are accompanied by a rapid escalation of antigen levels over 1-2 weeks followed by a gradual decay in antigen levels over ~4 weeks (acute) or sustained levels of antigen (chronic). Bolus injections provide a rapid burst and decline in antigen levels due to rapid clearance. This transient exposure can be adjusted by using repeated injection dosing or osmotic pump-driven vaccination. Recently developed nucleic acid vaccines can sustain antigen expression over prolonged periods.