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Genetic engineering is also used to manufacture subunit vaccines , which are safer than other vaccines because they contain only a single antigenic molecule and lack any part of the genome of the pathogen (see Vaccines ). For example, a vaccine for hepatitis B is created by inserting a gene encoding a hepatitis B surface protein into a yeast; the yeast then produces this protein, which the human immune system recognizes as an antigen. The hepatitis B antigen is purified from yeast cultures and administered to patients as a vaccine. Even though the vaccine does not contain the hepatitis B virus, the presence of the antigenic protein stimulates the immune system to produce antibodies that will protect the patient against the virus in the event of exposure. U.S. Department of Health and Human Services. “Types of Vaccines.” 2013. http://www.vaccines.gov/more_info/types/#subunit. Accessed May 27, 2016. The Internet Drug List. Recombivax . 2015. http://www.rxlist.com/recombivax-drug.htm. Accessed May 27, 2016.

Genetic engineering has also been important in the production of other therapeutic proteins, such as insulin , interferons , and human growth hormone , to treat a variety of human medical conditions. For example, at one time, it was possible to treat diabetes only by giving patients pig insulin, which caused allergic reactions due to small differences between the proteins expressed in human and pig insulin. However, since 1978, recombinant DNA technology has been used to produce large-scale quantities of human insulin using E. coli in a relatively inexpensive process that yields a more consistently effective pharmaceutical product. Scientists have also genetically engineered E. coli capable of producing human growth hormone (HGH), which is used to treat growth disorders in children and certain other disorders in adults. The HGH gene was cloned from a cDNA library and inserted into E. coli cells by cloning it into a bacterial vector. Eventually, genetic engineering will be used to produce DNA vaccines and various gene therapies, as well as customized medicines for fighting cancer and other diseases.

Some Genetically Engineered Pharmaceutical Products and Applications
Recombinant DNA Product Application
Atrial natriuretic peptide Treatment of heart disease (e.g., congestive heart failure), kidney disease, high blood pressure
DNase Treatment of viscous lung secretions in cystic fibrosis
Erythropoietin Treatment of severe anemia with kidney damage
Factor VIII Treatment of hemophilia
Hepatitis B vaccine Prevention of hepatitis B infection
Human growth hormone Treatment of growth hormone deficiency, Turner’s syndrome, burns
Human insulin Treatment of diabetes
Interferons Treatment of multiple sclerosis, various cancers (e.g., melanoma), viral infections (e.g., Hepatitis B and C)
Tetracenomycins Used as antibiotics
Tissue plasminogen activator Treatment of pulmonary embolism in ischemic stroke, myocardial infarction
  • What bacterium has been genetically engineered to produce human insulin for the treatment of diabetes?
  • Explain how microorganisms can be engineered to produce vaccines.

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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