Understanding Biotechnology

What is Biotechnology

Overview of Biotechnology

History of Biotechnology

Why do we do biotechnology?

Biotechnology for the environment

Biotechnology for food and agriculture

As well as using genetically modified bacterial cells, GM yeasts are often used to produce the large protein molecules of some hormones.

Insulin for diabetes

The majority of insulin used by people to manage diabetes is produced using biotechnology. Bacterial cells are genetically modified to produce large quantities of human insulin, which is then purified for therapeutic use. Millions of people worldwide now use Humuline, which is a major brand name for ‘human’ insulin produced using GM bacteria.

For many years, individuals with diabetes were treated with insulin derived from the pancreases of abattoir animals (usually pigs and cows). Although animal insulin is similar to the human form, there are some differences. This means that some individuals cannot tolerate it. There are also issues regarding the sustainable use of animals for this purpose.

Some human proteins that have been generated in similar ways to insulin include human growth hormone, blood-clotting factors needed to treat haemophilia, and erythropoietin, which is used to treat anaemia.

As well as using genetically engineered bacterial cells, engineered yeast are often used to produce the large protein molecules of some hormones.

For many years, individuals with diabetes were treated with insulin derived from the pancreas of abattoir animals (usually pigs and cows). Although animal insulin is similar to the human form, there are differences which means some individuals cannot tolerate it and there are issues regarding the sustainable use of animals for this purpose. The advent of biotechnology radically changed this. By inserting a copy of the human insulin gene into a bacterial vector, it was possible to produce insulin chemically identical to the naturally produced form.

Millions of people worldwide now use Humulinë, which is a major brand name for ‘human‘ insulin produced using this method

Vaccines

Most vaccines contain one of the following:

• low doses of dead pathogenic (disease-causing) microorganisms
• inactivated toxins from pathogenic bacteria
• weakened live pathogenic organisms that are unable to cause the severe form of the disease.

The body recognises a vaccine as a foreign substance. The cells of the immune system mount an immune response to destroy it, producing specific antibodies that recognise the foreign substance. The antibodies remain in the body, ready to fight future infections of the naturally-occurring form of the disease.

Read more about the immune system: http://health.howstuffworks.com/immune-system.htm

Vaccines have revolutionised the fight against infectious diseases. They are used to control life-threatening illnesses such as measles, polio, tuberculosis, tetanus, rabies, smallpox, cholera, typhoid fever, diphtheria, pertussis (whooping cough), Japanese encephalitis and yellow fever.

The practice of vaccination began in England in 1796, when Edward Jenner vaccinated an eight-year-old boy against smallpox by using the closely related cow pox virus. Smallpox is an acute, contagious, and sometimes fatal disease causing fever and raised skin rashes. In 1980, after a worldwide vaccination program, smallpox was declared completely eradicated.

A global campaign to eradicate polio is currently underway. Polio is a highly infectious disease that mainly infects children, particularly in developing countries. The polio virus attacks the nervous system and can cause total paralysis in a matter of hours. Those who survive are faced with life-long health problems.

These days, v accines are researched and developed in a very different way from earlier methods. Genetic modification techniques allows a gene coding for a protein of a disease-causing organism to be isolated and transferred into bacteria.

The GM bacteria then produce large quantities of the protein that can be purified and used as a vaccine. This approach has also been used with GM yeast, which produce hepatitis B vaccine.

Researchers have been looking at ways to produce edible vaccines, making vaccination programs as easy as eating a piece of fruit or vegetable. They hoped that such foods could be grown and administered in developing countries, providing cheap sources of vaccines without needing costly refrigeration or needle injections.

However, developers decided not to pursue this research, to avoid any possibility of vaccine-laden food straying into shops or markets. If this occurred, it could be unwittingly eaten by consumers, with unpredictable results. Instead, developers are now focusing on making vaccines in edible parts of plants that are not sold as food.

While edible vaccine research has been largely directed at preventing human diseases, the same technology could be valuable for the production of vaccines to add to animal feed.

The first ‘prototype’ edible vaccines were produced in GM potatoes and tobacco leaves. The plants were genetically modified to produce a toxin from the bacterial Escherichia coli strain that causes severe intestinal disease, which can be fatal in developing countries. The GM potatoes and tobacco leaves were fed to laboratory mice. Their immune systems mounted a sufficient response to the toxin to protect their bodies from the bacterium in further experiments.

In similar experiments, the gene for a non-toxic part of the cholera toxin has been inserted in GM alfalfa plants. Mice fed with this alfalfa produced an immune response against the cholera toxin.

GM tomato and lettuce plants have also been produced that contain the gene encoding the hepatitis B surface protein. GM rice and lettuce for use as a measles vaccine, GM tomatoes for rabies and HIV vaccines, and GM tomato and potatoes for respiratory syncytial virus vaccine are also under development.

One or more genes from a pathogen  are copied and multiplied using a common laboratory technique called polymerase chain reaction (PCR). The copied genes are injected into muscle cells of the organism to be vaccinated.

A few muscle cells will take up the genes and  make their protein product. For viral pathogens, this will usually be a virus surface protein. The organism’s immune system recognises the gene product as foreign and remembers it, just as in conventional vaccination.

Some advantages of DNA vaccination are:

• Purity: because DNA vaccines are made artificially, they  are much purer than if made directly from pathogens.
• Specificity: the vaccine contains only one of the many genes necessary for pathogen reproduction. The small amount of DNA is enough for the recipient’s immune system to recognise as foreign, but not enough to cause illness.
• Different genes can be mixed and injected at the same time, making it possible to simultaneously vaccinate against variants of a pathogen or several different pathogens.
• Cost and ease of storage. Unlike conventional  protein-based vaccines, DNA vaccines are inexpensive to produce, don’t require refrigeration and can be stored for a long time.

DNA vaccination is still an experimental procedure, as very few trials have demonstrated an immune response strong enough to protect against disease. Current studies include avian influenza and West Nile virus DNA vaccines, and a DNA vaccination against multiple sclerosis

Biopharming

Any GM animal or plant used for pharmaceutical or chemical production must be able to produce the desired compound at high levels, while not endangering its own health. It must also be able to pass this ability to its offspring.

Pharming with animals

The section of human DNA containing the genes for the required protein is injected into the animal embryo. The embryo is then placed into the uterus of a surrogate mother where it develops to full term. The adult GM animal's milk produces the human protein, which is purified for therapeutic use for humans.

This technology was first used in 1987. GM mice produced tissue plasminogen activator, a human protein used to treat blood clots. Other research has included:

• cows that produce
  • human serum albumin, used to maintain fluid balance in the blood
  • lactoferrin, a protein from breast milk that promotes infant growth
• sheep that produce
  • factor VIII and factor IX, essential for blood clotting
  • natural anticoagulants used during heart surgery
  • proteins to treat lung and liver disease
• rabbits that produce
  • human lactoferrin
  • human interleukin-2, a protein essential in the immune response to infection and may be useful in fighting some types of cancer.

Pharming with plants

Plants make relatively cheap pharmaceutical and chemical ‘factories'. In the same way that sugarcane is harvested and refined to produce sugar, compounds produced inside a GM plant are extracted and processed after harvesting. Instead of producing a food or fibre product, the end result could be a medicine, a plastic, or even an additive used in the manufacture of paper. For example, researchers in South Africa and England are developing GM tobacco, bananas and potatoes containing a vaccine for human papilloma virus, which causes cervical cancer.

Corn is by far the most popular biopharm plant, followed by soybeans, tobacco and rice. Around the world some 400 biopharm products are reportedly in the pipeline, and more than 300 open-air field trials have already been conducted in locations across the USA.

• tobacco is a non-food crop, reducing the risk of someone accidentally eating a plant containing pharmaceuticals. In Australia , it is also grown in a highly regulated environment.
• bananas are sterile, so there is no risk of the new gene being transferred to other banana plants through cross-pollination.
• sugarcane produces large amounts of plant material or biomass and can also be grown essentially as a sterile crop.

Commercial production of biopharmed pharmaceuticals is still some time away, although some compounds are already produced in plants for laboratory and diagnostic work. Issues of commercial production that need consideration include:

• the large scale of crops required to produce compounds in sufficient quantity
• ensuring that the plants do not cross-pollinate, potentially transferring modified genes to other plant species. One way to prevent this is by creating sterile male plants.