Plant made vaccines (PMVs)
A vaccine is an antigenic preparation used to establish immunity against a disease and the main aim of the vaccination is to eradicate infectious diseases. In the beginning (Prakash, 1996; Artnzen, 1997)proposed that plants can be engineered for the production of vaccines. Several antigenic determinants belonging to various pathogens causing variety of diseases including bacterial and viral diarrhea, anthrax, rabies, cancer, SARS, measles, HIV, diphtheria, pertusis, tetanus, tuberculosis, respiratory syndrome, Alzheimer's disease, malaria, foot and mouth disease of cattle, gastroenteritis, hemorrhagic disease, bursal disease, goat plague, rinder pest virus, cytomegalovirus infections, parvoviral infections of dogs, avian influenza and bovine pneumonia have been produced in plants (Khandelwal et al., 2003; Sharma et al., 2004; Streatfield and Howard, 2003; Tiwari et al., 2009; Youm et al., 2008). In recent years, a large number of antigens have been produced in plants and shown to activate the immune response against the antigen in the animal models. Dow Agro Sciences has received the first ever regulatory approval for plant-made vaccine from the USDA Center for Veterinary Biologics (CVB) in January 2006.
In addition to the production of vaccines for diseases of humans in plant systems, attempts were also made to develop transgenic plants for the production of veterinary vaccines too. Attempts have been made for the production of vaccines for foot and mouth disease (FMDV), bovine rotavirus disease virus (BRV) and bovine viral diarrhoes virus (BVDV) in plants (Santos and Wigdorovitz, 2005). Even though plant based expression system is a very attractive alternative to the conventional methodologies, low expression level of the antigen in plants is the main drawback.