2. VACCINES
VACCINES ARE NON-TOXIC OR NON-VIRULENT PREPARATION OF ANTIGENIC
MATERIAL THAT CAN BE USED TO INDUCE LONG TERM HUMORAL AS WELL AS A
CELL MEDIATED IMMUNE RESPONSE AGAINST PATHOGENS.
3. Ideal Vaccines
Cost Effective
Effective after a single dose
Applicable to number of diseases
Administered by oral route
Could be given early in life
4. Recombinant DNA Vaccines
DNA vaccines, also known as genetic vaccines, use the genetic material of the
pathogen itself to immunize the individual. In this class of vaccine, fragments of the
pathogen's genome encoding antigenic proteins are injected directly into the host
cells where they can integrate into the chromosomal DNA.
Expression of genes within the host generate foreign particles to which the host
immune system responds.
Hence, in DNA vaccines, an immune response is made against the protein encoded
by the vaccine DNA.
The DNA itself is not immunogenic.
DNA vaccines itself induce both humoral as well as cell mediated immunity.
5.
6.
7. Recombinant DNA vaccines are 3rd generation vaccines, that is, plasmids/genes are
responsible for antigen formation.
These vaccines can be administered through
* Intramuscular injection (intradermal injection)
* Gene gun delivery (involves pressure delivery of plasmid coated gold beads)
* Nasal spray
8. Advantages
DNA vaccines induce both humoral and cell mediated immunity.
DNA vaccines cause prolonged expression of the antigens, thus leads to longer
protection.
Refrigeration of DNA vaccines is not required which greatly lowers the cost and
reduces complexity of delivery.
9. Limitation
Only protein antigens can be encoded. Vaccines where polysaccharide antigens are
to be used (eg:- pneumococcal and meningococcal vaccines) could not be made.
10. Current Scenario
Human trials are going on for DNA vaccines produced for-
* AIDS
* Influenza
* Ebola
* Herpes virus
* Malaria
