What are recombinant $DNA$ vaccines? Give two examples of such vaccines. Discuss their advantages.

(N/A) recombinant vaccine is a vaccine produced through recombinant $DNA$ technology.
This involves inserting the $DNA$ encoding an antigen that stimulates an immune response into bacterial or mammalian cells.
Recombinant $DNA$ technology has allowed the production of antigenic polypeptides of pathogens in bacteria or yeast.
Vaccines produced using this approach allow large-scale production and hence greater availability for immunization,e.g.,Hepatitis $B$ vaccine (Recombivax $HB$) produced from yeast.
Another example is the Japanese encephalitis vaccine $(IMOJEV)$,which is a recombinant live-attenuated vaccine.
Advantages of recombinant $DNA$ vaccines:
$(1)$ There is no risk of infection as they do not contain live pathogens.
$(2)$ Ease of development and large-scale production.
$(3)$ High stability for storage and shipping.
$(4)$ Cost-effective compared to traditional methods.
$(5)$ Efficient expression and purification of recombinant proteins.
$(6)$ Long-term persistence of the immunogen in the body.
$(7)$ In vivo expression ensures the protein closely resembles the normal eukaryotic structure,including necessary post-translational modifications.