Live attenuated vaccines differ from inactivated vaccines because they:
Live attenuated vaccines developed through classical virology approach reducing pathogenicity while retaining replicative capacity that mimics natural infection without causing severe disease. Attenuation strategies include serial passage in heterologous host cells like chick embryo fibroblasts, embryonated eggs, or at subphysiologic temperature 25 to 33 degrees cold adaptation accumulating adaptive mutations in polymerase genes L and P reducing transcription efficiency in human cells at 37 degrees, plus mutations in surface glycoprotein cleavage sites reducing fusogenicity and in interferon a
Ref: Plotkin Vaccines 7th ed live attenuated replication PAMP; Abbas Cellular Molecular Immunology Sabin polio reversion risk.
