Vaccine; To be effective  Must stimulate as many of the body's defence mechanisms as possible.  It is not necessary to get 100% uptake of vaccine in population.  This strategy is most effective where there is no alternative host for the virus.

OPTIMAL AGE 2-3 months of age  2-3 months of age  Maternal antibodies:  BCG, smallpox, and polio: Local multiplication (Not affected by Abs) * BCG (Bacillus Calmette Guerin)  Measles, mumps, and rubella: Systemic spread (Affected)

SPACING OF PRIMARY INJECTIONS  UK:  DTP/Polio (OPV): o 1,2 and 3 dose: 1 month intervals o 4th dose: (At 3-5 years)  MMR At 15 month (At 4-6 years (Booster)) (At 4-6 years (Booster)) DPT: Diptheria, Pertussis, Tetanus DPT: Diptheria, Pertussis, Tetanus OPV: Oral Polio Vaccine OPV: Oral Polio Vaccine MMR: Measles, Mumps, Rubella MMR: Measles, Mumps, Rubella

SPACING OF PRIMARY INJECTIONS  USA:  DTP o 1,2 and 3 dose: 2 months interval o 4th dose: At month o 5th dose: At 4-6 years  IPV At 6-18 month At 4-6 years (Booster) At 4-6 years (Booster)  MMR At 15 month At 4-6 years (Booster) At 4-6 years (Booster) DPT: Diptheria, Pertussis, Tetanus IPV: Inactivated Polio Vaccine IPV: Inactivated Polio Vaccine MMR: Measles, Mumps, Rubella

Types of Vaccines  Inactivated vaccines: Exposing the virus to a denaturing agents (Loss infectivity without loss of antigenicity)  Advantages: - No infectious agents - Stable  Disadvantages: - Not suitable for all viruses - Not suitable for all viruses - Moderately Effective - No Mucosal & CMI - No Mucosal & CMI

Types of Vaccines, Continues  Live (Attenuated) vaccines: Grow the virus under unfavorable conditions (Can replicate but cause no disease)  Advantages: - Good immunogens - Long lasting immunity  Disadvantages: - Unstable - Unstable - Revert to virulence - Contamination - Contamination

 Subunit vaccines: Parts of virus  Advantages: - Safe - Safe  Disadvantages: - Poor antigenicity - Poor antigenicity - Need Carriers & Adjuvants - Need Carriers & Adjuvants - Expensive - Expensive Types of Vaccines, Continues

 Types: - Synthetic vaccines: Short, Chemically synthesized peptides - Synthetic vaccines: Short, Chemically synthesized peptides. Advantages:. Advantages: - Safe, Can be designed to any desired sequence - Safe, Can be designed to any desired sequence. Disadvantages:. Disadvantages: - Poor antigenicity, Need Carriers & Adjuvants, - Poor antigenicity, Need Carriers & Adjuvants, Expensive Expensive

Types of Vaccines, Continues  Types: - Recombinant vaccines: Plasmid + Foreign DNA; e.g., HBV - Recombinant vaccines: Plasmid + Foreign DNA; e.g., HBV Advantages: Advantages: - No infectious agent (DNA  Protein) - Good for viruses do not grow in tissue culture - Good for viruses do not grow in tissue culture - No side effect - No side effect Disadvantages: Disadvantages: - Separation & purification - Similarity to the right Ag

Types of Vaccines, Continues  Types: - Virus vectors: Virus + Foreign DNA; Vaccinia Virus - Virus vectors: Virus + Foreign DNA; Vaccinia Virus Advantages: Advantages: - Safe - Effective - Effective Disadvantages: Disadvantages: - Difficult to produce - Previous immunity; Use Avipoxvirus (Bird poxvirus) - Immunity against the vector

Types of Vaccines, Continues  DNA vaccines: Plasmid + Gene of interest  Cell  Advantages: - Post-translational modification - Post-translational modification  Disadvantages: - Degraded DNA (1/million copies enter cells) - Degraded DNA (1/million copies enter cells) - Insertional mutagenesis (Mutation in cells) - Insertional mutagenesis (Mutation in cells) - Autoimmune responses (Anti-DNA Ab) - Autoimmune responses (Anti-DNA Ab) - Immunologic tolerance (No response to the expressed protein - Immunologic tolerance (No response to the expressed protein

© Elsevier, 2005.