Essay on the Vaccines for Hepatitis B
The most common agent of acute hepatitis is a virus called ‘Hepatitis B virus’. In 1963, Baruch Blumberg discovered Hepatitis B virus. He went on to construct a vaccine against Hepatitis B.
This virus is also known to cause liver cancer. It consists of 3 kilo base pairs long double stranded circular DNA covered inside a proteinaceous coat called capsid.
There are three types of capsid proteins that shows antigenicity (i.e. produces antibodies in blood). These antigens are: hepatitis B virus core antigen (HBcAG), hepatitis B virus surface antigen (HBsAG) and e-antigen (HBeAG).The antigens are expressed by its respective genes.
The HBsAG is the outer coat of Hepatitis B Virus. It is recognised as a specific marker for its infection. It becomes detectable in circulation about a month after exposure to infection.
Hepatitis is a serious disease. In India, there are 43 million estimated HBV carriers (4.7%) comprising the second largest pool of HBV carriers in the world. The prevalence of HBV in the dialysis population in India is reported to range between 3.4 and 43% which is several folds higher than the carrier rate in general population.
The earliest symptoms of hepatitis are: nausea, vomiting and fatigue. There is marked distaste to cigarettes and coffee. One may also have body ache, joint pain, headache, sore throat. A low grade fever may also be present. This is followed by dark urine and clay colored stools. Ultimately there develops jaundice.
After a variable period starts the recovery phase during which the general condition gradually improves.
This virus is transmitted through agency of blood and body fluids. Hepatitis caused by it can range from a mild one to a fatal one.
1. Vaccines for Hepatitis B Virus :
Two vaccines are in current use: serum-derived vaccine and recombinant vaccine. Both contain purified preparations of the hepatitis B surface protein.
It is produced by transferring HBsAg gene into a plasmid. Then the plasmid is inserted into yeast cells. The yeasts are allowed to grow in a large sized fermentor for production of recombinant protein called HBsAg protein.
These proteins are then purified and tested which later on acts as HBV vaccine. Recombinant DNA hepatitis B vaccines provide safe and reliable protection from hepatitis B when used either before or immediately after exposure to the virus.
Tests show that 90-95% of vaccination of healthy people result in the development of resistance against hepatitis B.
2. Biotech Industry in India:
In India, Andhra Pradesh has several pioneers in Biotech industry such as Shantha Biotechnics Private Ltd., Bharat Biotech International Ltd., Biological E. Ltd., Indian Immunologicals Ltd., Krebs Biochemicals, Jupiter Orga, Dr. Reddy’s Laboratories, Godrej Plant Biotech Ltd., AG. Biotech Laboratories (India) Ltd., Biochemical and Synthetics Products Private Ltd. Biotissues Pvt. Lab. Ltd, Classic Biotech and Exports Ltd, Fortune Biotech Ltd, Harita Biotech and Plantations, Mericlone Bioteck Private Ltd., Metchnikoff Biosystems Pvt. Ltd., Nuziveedu Seeds Ltd., Prabhat Agribiotech Ltd., Sun Floriculture Biotech Ltd., Transgene Biotek Ltd., Vermigreen Bio-fertilizers, Godavari Fertilizers and Chemicals Ltd., Viswa Mitra Bio Agro Ltd., amongst others, who have created a critical mass for the industry. Annual turnover of some of the biotech industries is given in.
At present, there are only two companies in India which have successfully commercialized biotech products based on recombinant DNA technologies and both are located in Hyderabad.
Shantha Biotechnics Pvt. Ltd., founded in 1993, is the largest biotechnology company in India in the private sector. It was successful in launching the India’s first genetically engineered human health care product – a vaccine for Hepatitis B with recombinant DNA technology under the brand name Shanvac B.
Bharat Biotech International Ltd. was set up with the aim of pursuing pioneering research in health care through genetic engineering and producing health care products for diseases endemic to India and the South East Asian Region. It was a pioneer in producing a Hepatitis-B vaccine based on recombinant DNA technology under the brand name of REVAC-B.
It is the first vaccine in the world to be produced without cesium chloride, a toxic metal. It is the second largest biotech facility for the manufacture of Hepatitis B in the world with a capacity of 100 million doses per annum.
It has a state-of-art of multi-product contract manufacturing, formulation and filling plant for biotechnology products. The company’s current research activities cover a third generation Hepatitis – B vaccine in collaboration with the Indian Institute of Science.
3. Transmission of Hepatitis B:
Hepatitis B is found in semen, vaginal secretions and breast milk. The virus can be transmitted during unprotected sexual intercourse and from mother to infant during birth and through breast feeding.
Synovial fluid (joint lubricant), amniotic fluid, cerebrospinal fluid, and peritoneal fluid (found in the abdominal cavity) can contain the hepatitis B virus.
But the risk of transmission to workers is not known. Faeces, nasal secretions, sputum, sweat, tears, urine, and vomit have not been implicated in the spread of hepatitis B. Unless they are visibly contaminated with blood, the risk of contracting hepatitis B from these fluids in the workplace is practically nonexistent.
Hepatitis B is not transmitted by casual contact. For example, hospital employees who have no contact with blood, blood products or blood-contaminated fluids are at no greater risk than the general public. However, the virus can spread through intimate contact with carriers in a household setting. Why this happens is not completely understood.
Somehow, the virus can find its way into the bloodstream of family members possibly because of frequent physical contact with the small cuts or skin rashes. The virus can also spread through biting and possibly by the sharing of toothbrushes or razors.