How is recombinant DNA be to develop a vaccine?

Cut & splice. Its my understanding that they can produce the code for creating the protein component of a germs cell wall & insert it into the dna of a common bacteria. They grow the bacteria in nutrient rich vats & the bacteria produce the protein in excess & expel it into the vat.That protein can be purified & becomes the basis of a vaccine. Neat technology that has cut down the frequency of vaccine reactions.