Viral Vector In Immunotherapy Biology Essay

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Today there are various diseases such as malignant lesions which are known as cancer in layman language, allergy which may be due to dust particles, pollen grains etc or asthma all such diseases are associated with the immune system of the individual. Therefore, these diseases can be treated efficiently using immunotherapy. Immunotherapy is a mode of treatment in which the patients' own immune system is raised to fight against the disease. This can be in done either by stimulating patients' own immune system or by injecting man made components to patients' body. In certain conditions we may need to suppress patients' immune system as in case of renal transplantation to reduce the chances of organ rejection.

In general when viruses attack they induce their own genetic material influencing host cells to produce more viral cells resulting in disease. But when disease causing genes of viruses are changed with good genes i.e. genes to generate the desired effect in host by integrating in genome or plasmid and transduce them. Such viruses are fit to work as an agent for transferring genetic information. These are viral vectors.

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Although hormonal therapy and chemotherapy are used to treat cancer but even more advanced mode of treatments are required which are least toxic and harmful to patients therefore now a days this mode of treatment is extensively used in treating tumors. This is done by transferring genetic information to the target cells and further this will promote production of therapeutic protein. This genetic information can be transferred using viruses as an agent which is known as a vector. Viruses are highly efficient in transferring genetic information and in inducing anti- tumor immune response. Immunotherapy raises the host immunity which will help to recognize and destroy tumor cells.

List of such viruses

Studies have shown recombinant vaccinia virus is na efficient vector in raising host immunity both cellular as well humeral.

 Viral vector rAAV2 expressing hIL15 for treatment of human cervical cancer. This viral vector is nonpathogenic in human with low immunogenicity compared with the other viral vectors.

Pox virus vector

Recombinant canarypox virus (ALVAC)

Adenovirus

Alpha virus vectors or alphavirus RNA replicon based particles vaccine for immunotherapy of cancer.

Viral vectors are also used in dendritic cell-based immunotherapy. Various viruses as Influenza virus, herpes simplex virus, adenovirus, retrovirus are used in transducing dendritic cells.

In conclusion, a large number of viral vectors have been identified with varied characteristics which can be used in treatment of various diseases. There are certain risks also associated with using viral vectors. These viruses may infect other healthy cells along with tumor cells of the host. Also are the chances that new gene may get attached to wrong location resulting in mutation. Need of the hour is to identify and use this methodology appropriately but with caution.

Infectious disease HIV infection

Infectious diseases are the diseases which are caused by pathogenic microorganisms such as bacteria, viruses, parasites or fungi (WHO). Some of them may be contagious or other non contagious, which can be spread, directly or indirectly, from one person to another.

Human Immunodeficiency virus is one of the well known virus which is spreading spontaneously in human community and resulting in large number of deaths every year.

The origin of HIV is still a doubt. It is believed that approximately hundred years ago it came from monkey to human in Africa. It world only began to pay attention to HIV in the early was discovered in 1980s, when deaths were noticed because of some mysterious illness in homosexual population of New York City and San Francisco (Goldman Bonnie: 2009). These patients were diagnosed with reduced CD4 T cells in the body resulting in reduced immunity. In 1983 it was diagnosed that this was due to a virus known as Human Immunodeficiency virus, belonging to the retro virus group of viruses (Daar Eric S).

Once an individual get infected with the virus his blood and genital secretions will be loaded with the virus regardless of the symptoms. Such infected persons can transmit this virus to any person if his mucous lining or tissue as eyes, mouth, vagina; comes in contact with the secretions of infected person. Therefore the most common ways for spreading this deadly virus as via sexual contact, needle prick injury which is most common mode of spread in doctors and nurses', via mother to new born which may be during pregnancy, labor or due to breast feeding (Daar Eric S).

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Immediately after exposure to the virus person gets HIV infection. He may or may not be present with the symptoms but can be a source of infection to others. The early symptoms are as headache, fever, sore throat, joint pain, diarrhea, night sweats and rashes. Others are as weight loss, fatigue, shortness of breath, Candida infection, loss of appetite etc i.e. flu like symptoms (Cichocki Mark: 2010). These primary infection symptoms may disappear in one or two week and this period is known as window period. During this period no antibodies have formed till now but if required viral loaded tests can be performed to know how many viral particles are in the blood but it is not confirmatory test. Tests for HIV involves two steps a) screen test; b) confirmatory test. Screening involves looking for the antibodies in the secretions. If it comes positive for confirmation western blot or indirect immune fluorescence assay test is performed. If blood screening shows less than 200 CD4 cells per milliliters of blood, then only this condition is known as AIDS (acquired immunodeficiency syndrome)(Nettlemen Mary D).

The treatment for HIV infection consists of antiretroviral medications which work by suppressing the virus but not curing the disease. This effective combination of drugs is highly active anti retroviral therapy or HAART. It will be more beneficial to start the as soon as when CD4 cell counts 500cell per milliliter of blood. "There are five major classes of anti-retroviral medications: (1) nucleoside reverse transcriptase inhibitors (NRTIs), (2) non-nucleoside reverse transcriptase inhibitors (NNRTIs), (3) protease inhibitors (PIs), (4) entry inhibitors, and (5) integrase inhibitors" (Nettlemen Mary D). The  group of drug given to the patient depends on patients requirement and after completing resistance test for drugs.

Prevention of HIV is possible by taking certain precautionary measures as avoiding sexual contact with unidentified partners, using effective mode of precautions during sexual intercourse. Needle prick injuries should be avoided by using correct method of needle holding, using more advanced syringe, and using all the precautions of infection control as eye protection, mouth protection, gown etc. Spread of infection to new born can be avoided by use of medicines during pregnancy and labor, and avoiding breastfeeding the child (Nettlemen Mary D). At most important such known or high risk patients should themselves take precautions to avoid the spread of this deadly infection and help in saving innocent lives.

Even after several trials till date no effective vaccine has come up for prevention of this virus. Throughout the world various clinical trials are undergoing for the development of curative medications for the infection. Therefore the community should be well educated to avoid this infection and the already sufferers should be counseled to improve their quality of life.