Viral vaccines are categorized into:
Live Attenuated – Weakened virus (e.g., MMR, Varicella, OPV).
Inactivated (Killed) – Chemically/physically inactivated virus (e.g., IPV, Influenza).
Subunit/Split-Virion – Contains viral components (e.g., Hepatitis B, Influenza split vaccine).
General Method of Preparation
A) Live Attenuated Viral Vaccines
Steps:
Attenuation – Virus is weakened through passage in cultures or genetic modification.
Cultivation – Grown in tissue cultures or embryonated eggs.
Harvesting & Purification – Collected and purified via filtration or ultracentrifugation.
Formulation – Stabilizers (e.g., sorbitol, gelatin) added.
Lyophilization – Freeze-drying for stability.
Quality Control – Tests for potency, sterility, and safety.
Examples:
Measles, Mumps, Rubella (MMR) vaccine.
Varicella (chickenpox) vaccine.
Oral polio vaccine (OPV) (Sabin).
B) Inactivated (Killed) Viral Vaccines
Steps:
Cultivation – Virus grown in tissue cultures or eggs.
Inactivation – Chemically (e.g., formaldehyde) or physically (e.g., heat).
Purification – Removes debris and residual chemicals.
Adjuvant Addition – Optional (e.g., aluminum compounds for enhanced immunity).
Filling & Packaging – Under sterile conditions.
Quality Testing – Ensures potency, sterility, and inactivation verification.
Examples:
Inactivated Polio Vaccine (IPV) (Salk).
Inactivated Influenza Vaccine.
C) Subunit / Split & Recombinant Viral Vaccines
Subunit – Contains viral proteins (e.g., Hepatitis B surface antigen).
Split-Virion – Chemically split virus.
Recombinant – Genetically engineered viral proteins (e.g., in yeast or mammalian cells).
Steps:
Gene Identification & Cloning – Target antigen gene cloned.
Expression & Harvesting – Produced in yeast, bacteria, or mammalian cells.
Purification – Isolated and purified.
Formulation – With or without adjuvants.
Quality Control – Ensures purity and immunogenicity.
Examples:
Hepatitis B Vaccine (recombinant HBsAg expressed in yeast).
Human Papillomavirus (HPV) Vaccine (virus-like particles).
