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.
3. Subunit vaccine-presents an antigen to the immune system without introducing viral particles. A weakness of this technique is that isolated proteins can be denatured and will then bind to different antibodies then the proteins in the virus. A vaccine is a biological preparation that establishes or improves immunity to a particular disease. Vaccines can prevent or ameliorate the effects of infection by a pathogen.