Bid rent theory in the central business district (CBD) [edit]. Land users, whether they be retail, office, or residential, all compete for the most accessible land within the CBD. The amount they are willing to pay is called bid rent.
Recombinant or purified protein vaccines consist of protein antigens that have either been produced in a heterologous expression system (e.g., bacteria or yeast) or purified from large amounts of the pathogenic organism.
Vaccines are medicines containing a preparation of weakened or dead  microbes of the kind that cause a particular disease which are  administered to stimulate the immune sysâ¦tem to produce antibodies  against that specific disease.