Vaccines have been traditionally made by using dead or weakened forms of bacteria or virus that would stimulate the immune system in the human body, but biotechnology is helping to re-engineer existing vaccines to be more effective against organisms that cause infectious diseases. Those apart, new vaccines are being made to cure serious illnesses like cervical cancer. These biotech engineered newer vaccines have only the antigen, not the actual microbe as in conventional vaccines.
Vaccines can be categorized into:
• Prophylactic vaccines
• Therapeutic vaccines
• Pediatric combination vaccine
Prophylactic vaccines prevent future infections from happening as for example the small pox vaccine. Therapeutic vaccines fight disease mechanisms such as infections, and addictions such as that for nicotine and cocaine. For example Celldex Therapeutics that focuses on precision targeted immunotherapies has made the Cholera GardeÂ® vaccine that is undergoing Phase 2 trials at the International Vaccine Institute. Another bacterial vaccine against enterotoxigenic E. coli is being targeted for use against enteric disease especially among frequent travelers. Celtic Pharma has developed TA-CD vaccine for the treatment of cocaine addiction and TA-NIC immunotherapeutic vaccine as an aid for cessation of smoking.
Pediatric combination vaccine is essentially a combination of several vaccines in a singly administered shot, as for example ProQuad that combines MMR and chicken pox Varivax vaccine; or Pediarix that combines vaccines for Tetanus, Hepatitis B, Polio, Pertussis and Diptheria.
How biotechnology has helped in the making of modern vaccines is best understood by understanding some practical examples of cutting edge technologies in the area of vaccine manufacture. Here are a few examples.
Conventional treatment of cancer entails radiation, chemotherapy, and surgery. Although there is no revolutionary cancer treatment medication as yet, immunotherapy is a newer tool based on the premise that the human immune system is the best medicine to treat cancer.
Overwhelming amount of research is being conducted in developing cancer vaccines several of which are in advanced clinical testing stages. These include vaccines for breast cancer, ovarian cancer, lung cancer, prostrate cancer and cervical cancer and other categories.
Every year more than 65,000 people suffer from non-Hodgkin's lymphoma in the US and this is usually a fatal disease. Biovest International has pioneered the AutovaxID an automated compact cell manufacturing device that makes patient specific therapeutic cancer vaccines custom made for an individual from the surface proteins of that individual's cancer cells.
So far cancer immunotherapy is mostly based on peptide vaccines. But Curevac have a unique m RNA manufacturing plant where RNActiveÂ® molecules are made and administered under the patient's skin. Since molecules are coded for tumor antigens, when they are transcribed into proteins by skin cells, the result is activation of the immune system to fight tumor
Oncophage made by Antigenics is a patient-specific therapeutic cancer vaccine (contains heat shock protein gp96 from the patients' own tumor tissue) which is FDA approved for the adjuvant treatment of kidney cancer patients and for glioma. Heat shock protein basically stimulates the immune system to combat cancer. Oncophage targets only cancerous cells and not normal cells and hence from toxicity point of view is advantageous in comparison to other cancer medication.
Genzyme has engineered a genetically modified mouse whose milk can be purified to make malaria vaccine. These mice have a gene for a surface protein from the vicious malarial parasite Plasmodium falciparum that would secrete protein into the milk when the gene gets switched on by the cells in the mammary glands of the mouse. Subsequently it was established that transgenic goats could be engineered to make proteins in their milk for making enough malarial vaccine.
Several factors contributed to the development of carbohydrate vaccines including the realization that antibiotics were not a cure all, as it generated resistant disease organisms; advanced knowledge about our immune system; and a better understanding of carbohydrate structure. For purpose of achieving immunization these types of vaccines target the surface carbohydrates of bacteria, virus, fungi and also cancer cells.
An example is the development of Hib Carbohydrate vaccine against Haemophilus influenzae for children under the age of 5 years. Another example is the S.pneumoniae Capsular Polysaccharide-Conjugate vaccine against S.pneumoniae infections.
Plant based vaccines
Potatoes and tomato have been considered as expression platforms for vaccine antigens, and the latter is especially favored as it does not require post harvest processing and could be even eaten fresh. Other plants reckoned as feasible for vaccine production include clover and pigeon pea. For example Dow AgroSciences has formulated a plant based vaccine for treating New Castle disease in poultry that is undergoing regulatory trials.
Plant based vaccines are being developed for human use on the assumption that oral administration of plant based antigens would be amenable to absorption in the digestive tract and hence stimulation of a mucosal immune response was possible, and that too with ease of use as it did not involve use of syringes.
Skin patch vaccines for tetanus, anthrax
Since the outer layer of skin is more immunosensitive than deep tissue, several adenovirus-vectored vaccines have been developed for application to the surface of skin.
For example the topical application of E. coli vectors expressing anthrax antigens was found to be very effective and similar method was adopted for preventing animals from tetanus too and so these vaccines have proved effective against live pathogens in a disease setting.
Concerns regarding biotech oriented vaccines
There are a lot of grey areas in biotech vaccines as it essentially involves material that is injected to the body which in normal course would not have been there and so there are several imponderables in terms of known and unknown genetic material and foreign proteins entering the body. Is this the cause of the spurt in autism, Pakinsonism and Alzhemiers and diabetes in children? That apart there is no guarantee that the sequential genetic codes of animal viruses used for making some vaccines may not interfere with human cell codes.
However the problem with vaccine production is the costs involved no matter if it is conventional or biotech engineered.
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