Scientists may soon have an answer to multiple sclerosis by injecting pieces of specific DNA as a vaccine.
Multiple sclerosis is one of the most dreaded diseases today. It typically affects men and women between 20 and 40. The classic early symptoms are stiffness and weakness. Myelin, the sheath that prevents currents in the nerve cells from leaking, is attacked by the immune system. The disease progresses gradually, with remissions in some patients, and could lead to complete paralysis. It has some famous victims, including physicist Stephen Hawking. Till date, there has been no cure to multiple sclerosis.
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DNA vaccines could be an effective method of treating autoimmune diseases
Now, however, some scientists have found a potential remedy â€” injecting a specific piece of DNA into the patientâ€™s muscles. The DNA gets into the muscle cells and produces a protein that is found in the myelin. This protein makes the patientâ€™s immune system tone down its attack on myelin. The technique was developed by the Californian company, Bayhill Therapeutics. In a Phase I clinical study in many hospitals in the US and Canada, patients showed positive changes in magnetic resonance imaging with no adverse reactions. â€œThe technique can be useful in treating many other diseases,â€ says Amit Bar-Or, co-lead author of the study and director of the experimental therapeutics programme at the Montreal Neurological Institute. A larger trial will start soon and the real advantage to patients can be seen only over long periods.
The process of injecting pieces of DNA and making them function as a vaccine is a new method for treating an autoimmune disease, but it has been tried with some success for preventing a variety of infectious diseases. Recently, Vical, another company based in California, began clinical trials on a DNA vaccine for pandemic influenza. Elsewhere in the world, trials are on for DNA vaccines for avian flu, AIDS, veterinary diseases such as rabies and so on. One DNA vaccine has been approved so far, for protecting horses against West Nile virus. The next commercial DNA vaccine could be for rabies in dogs, being developed by the Indian Institute of Science (IISc) in Bangalore.
Traditional vaccines are made using either killed or weakened microorganisms. Vaccines against influenza, hepatitis A and cholera are of the first variety, while those for yellow fever, mumps and rubella of the second. Some vaccines are made from the toxins of viruses, the most important example being tetanus. Sometimes, a part of the microorganism is also used as a vaccine. In all these cases, the vaccine consists of proteins â€” called antigens â€” that trigger an immune response, forcing the body to produce antibodies that can protect the recipient from the disease. In recent years, genetic engineering has been used to produce viral proteins that trigger the immune response.
In DNA vaccines, no protein is injected into the body. The vaccine consists of a piece or pieces of DNA that code for these proteins. Muscle cells take the DNA inside and then start producing the protein antigens. This technique has many advantages over protein-based vaccines. First, you can produce the DNA very quickly, much more easily than you can produce the proteins. This becomes very advantageous when the microorganism is complex or changes rapidly. â€œUsing DNA is the only way of developing vaccines for complex diseases such as tuberculosis or malaria,â€ says P.N. Rangarajan, associate professor of biochemistry at IISc. The second advantage of DNA vaccines â€” particularly useful in India â€” is that they need no cold chain (supply system maintained at a controlled, low temperature).
Rangarajan and his team have developed a DNA vaccine for dogs against rabies. Scientists generally believe that getting approval for veterinary products is easier than for humans, particularly when dealing with cutting-edge, unproven technologies. IISc had transferred the technology to the Indian Immunologicals in Hyderabad, and this company â€” the clinical trials are over â€” now has to get approvals for manufacturing the product from the Drug Controller General of India. It would then become the second commercial DNA vaccine in the world.
Several DNA vaccines â€” for HIV, bird flu, Ebola and influenza â€” are currently being developed. Yet, many experts are not entirely convinced about their safety and efficacy. One fear is that the DNA vaccine could integrate into the chromosomes and then the genetic material of the host. This could cause mutations in the genes and that could lead to cancer. However, this is only in theory, and vaccines so far tested have been found to be harmless. Their efficacy is the more serious concern for most scientists. With more and more DNA vaccines being developed, these doubts are also easing.
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.
Source: The Telegraph (Kolkata, India)