Plantibodies

We have so far seen expression of antigens in plants.
Expression of antibodies in plants is an example of passive immunity. So now, let us see how this works.

Antibodies produced in plants are known as “plantibodies”. To date, only 4 antibodies produced in plants have the potential to be used as therapeutic agents and only IgG-IgA against Streptococcus mutans has been tested on humans.
Producing complete secretory antibodies(which are different from regular antibodies) is quite difficult because apart from 4 protein chains normally found in antibodies(two heavy, two light chains), they contain two additional proteins, one of which is added in vivo during secretion. This was finally achieved by crossing four separate lines of transgenic tobacco plants. Other approaches involve double transformation, or transformation by constructs having genes for both light and heavy chains on the same vector.
This process occurring in plants can be exploited to great advantage.
Plantibodies can be easily purified from the plant and can specifically prevent infections with the Herpes virus without causing any damage to mice. The greatest advantage offered by plantibodies is the economy factor; large amounts of the plant bodies can be purified at a reasonable cost.
The yield is also much higher: the production of plant antibody involves transplanting a human gene into corn reproductive cells and adding other DNA that increases cell production of the foreign protein. The yield of plant antibodies would be about 1.5 kilograms per acre of corn.
They also reduce risk of infection. Cells in fermentation tanks can catch human diseases but plants do not. However, it must be ensured that the plantibodies are free from pesticides and other kinds of contaminants.
Antibodies expressed in seeds are preferred over antibodies in leaves, which require immediate extraction since they decay earlier. In contrast, antibodies in seeds can be preserved for long at room temperature until their extraction or consumption.
HBV (Hepatitis B virus) antibodies in tobacco plants are being investigated. A number of other plantibodies like anti-HIV antibodies are under development.
Cultivating soya beans that contain human antibodies against herpes simplex virus 2, a causative agent of venereal disease, may result in an economically viable drug that may be added to contraceptives which are commercially available. Presently, investigation is on anti-tooth decay mouthwash made with antibodies extracted from transgenic tobacco plants.
Monoclonal antibodies (MABs) against STDs like genital herpes have been expressed in soybean.
Topical application of antibodies has already been shown to control infection by way of passive immunization.
It is an amazing exciting new technology and I know I’ll try my best to keep abreast of it. Won’t you?

Do comment!

References:
a.http://www.expresspharmaonline.com/20051215/research02.shtml
b.Lal P, Ramachandran VG, Goyal R, Sharma R. Edible vaccines: Current status and future. Indian J Med Microbiol [serial online] 2007 [cited 2008 May 2];25:93-102.
Available from: http://www.ijmm.org/text.asp?2007/25/2/93/32713
c.http://www.ias.ac.in/currsci/aug25/articles20.htm