Dry powder measles vaccine: Particle deposition, virus replication, and immune response in cotton rats following inhalation

A stable and high potency dry powder measles vaccine with a particle size distribution suitable for inhalation was manufactured by CO2-Assisted Nebulization with a Bubble Dryer® (CAN-BD) process from bulk liquid Edmonston-Zagreb live attenuated measles virus vaccine supplied by the Serum Institute of India. A novel dry powder inhaler, the PuffHaler® was adapted for use in evaluating the utility of cotton rats to study the vaccine deposition, vaccine virus replication, and immune response following inhalation of the dry powder measles vaccine. Vaccine deposition in the lungs of cotton rats and subsequent viral replication was detected by measles-specific RT-PCR, and viral replication was confined to the lungs. Inhalation delivery resulted in an immune response comparable to that following injection. The cotton rat model is useful for evaluating new measles vaccine formulations and delivery devices.