Tobacco Promising Factory For Pharmaceuticals

A
news release from
Virginia Tech reports some research
that may give tobacco a new lease on life if the anti-smoking forces
ever gain a full victory. The
release states, 

Blacksburg, Va. — The economics of producing
biopharmaceuticals from transgenic plants such as tobacco is still a roadblock
to producing large quantities of urgently needed medicines, especially for
people in underdeveloped nations.

Chenming (Mike) Zhang is testing a variety of ways to economically recover
recombinant proteins from transgenic tobacco using different protein separation
techniques.

Zhang, an assistant professor in the Department of Biological Systems
Engineering (BSE) in the College of Engineering at Virginia Tech, is working
with a team of three Ph.D. students to develop transgenic tobacco plants able to
express recombinant proteins economically. Recombinant proteins are potential
therapeutic agents for treating human and animal diseases and creating new
vaccines. Plant-made vaccines are especially beneficial because plants are free
of human diseases, reducing the cost to screen for viruses and bacterial toxins.

“Recombinant protein production from transgenic plants is challenging, not
just from the molecular biology aspect of creating high expression plant lines,
but also from the engineering aspect of recovering and purifying the proteins
economically — the importance of which cannot be overlooked,” Zhang said.

Recombinant proteins are proteins expressed by a host other than their native
hosts. For example, if the gene for human growth hormone is inserted into the
genetic code of yeast (gene recombination), then the corresponding protein
expressed in the yeast is called recombinant human growth hormone.

Zhang’s research starts with introducing the genes of interest into tobacco
plants and then developing economical processes for recovering and purifying the
expressed proteins.
Relaxin, one of the proteins his team is studying, could
potentially benefit patients with asthma, hay fever, and even cardiovascular
disease.

Because most recombinant proteins are for therapeutic uses, they need to be
highly purified to be safe for human use. Thus, once a protein is expressed,
whether by transgenic tobacco or bacteria, the protein first needs to be
recovered into liquid solutions before purification.

“Because of the high purity required, the purification is rigorous and not
surprisingly, very expensive. Therefore, development of more economical
techniques for protein purification is always an engineering challenge in order
to lower the cost of therapeutic proteins or biopharmaceuticals,” Zhang said.

Zhang uses tobacco in his research because it is a non-food crop and is well
suited as a “factory” for recombinant protein production. The leafy green
tobacco plant is relatively easy to alter genetically and produces thousands of
seeds and a great deal of biomass. As a non-food crop, genetically manipulated
tobacco will not pose a safety threat to products consumed by humans. “Since
tobacco is neither a food nor a feed-crop, transgenic tobacco will not enter our
food chain,” Zhang said.