Microbial Genetics
This is an area of study within microbiology and genetic engineering that studies the inheritable characteristics of microorganisms. It is an area of study of great significance in the field of health and medicine. In this essay I will be focusing on this significance both positive and negative as it relates to the field of health and medicine and the new ways in which genetic engineering is finding its application.
HIV infection usually infects cells with CD4+ markers. The other markers that are essential in making infection of these cells possible are CCR5 and CXCR4 without which cell entry by the virus is next to impossible. The cells that have these characteristics include T helper’s cells, macrophages and dendritic cells. T helpers cells are responsible in the regulation of both antibody mediated and cell mediated immunity. So it goes without saying that once these cells are infected and destroyed by the HIV virus or the cytotoxic T cells immunosuppression will set in. This will expose the patient to opportunistic infection that often proves very dangerous at this stage of the disease.
A case that was purely coincidental though significant was the one of the Berlin patient. The American patient was suffering from leukemia and was in Germany for bone marrow transplant. In addition to this the patient was HIV positive. After chemotherapy that targeted his cancerous blood cells the patient received marrow from a donor who had a double defective CCR5 gene. It’s said that one percent of Caucasians possess this defective gene. The resultant effect was the man became cured not only from leukemia but also from HIV since HIV could not enter to infect his ‘defective’ cells.
Following these microbial geneticists proposed to edit T cells in the patient’s immune system to render these cells resistant to the Human Immunodeficiency Virus. In the New England journal researchers were able to knock out the gene that code for the Chemokine co receptor (CCR5). CCR5 protein serves as the perfect lock that can be opened by the virus to gain access into the cell. Without it the entry of HIV into the cell is limited. Blood of patients who were on ante retro viral was taken, the CCR5 knocked out the cells were reintroduced into the patient and allowed to multiply. With this therapy a few patients demonstrated a reduction in viral load even after a periodic withdrawal of the drugs.
The observed benefit wasn’t long loved as the infused cells started decline with time. Research is still ongoing on how to perfect this therapy. The geneticists hope to effect a functional cure by rendering the body resistant to HIV infection. If these succeed it will be a remarkable breakthrough that will solve the menace that is HIV. It will totally improve whole economies especially of nations that bear the largest brunt of HIV infections and death like Botswana in the Sub Sahara while doing away with lifelong medication for patient with HIV. This case of advancement in microbial genetic shows how significant this field is in terms of the potential economic and social impact.
Despite being a dangerous virus that is major killer it’s not all doom and gloom for HIV as it finds its ways in gene therapy for other genetic conditions. It’s like the old adage is proving true once more that there is too much bad in the best of us and too much good even in the worst of us. HIV is finding itself being looked as a friend and not as a foe as it was once considered.
HIV belongs to a class of virus that is called retrovirus. It has a positive strand RNA genome that need to be reverse transcribe to result in viral DNA with the help of an enzyme called reverse transcriptase. This resultant viral DNA is then integrated into host cell DNA and act as the proviral DNA. Form the proviral DNA a messenger RNA is made that codes for viral proteins.
Scientists have been able to manipulate this novel virus so that it can serve as a carrier for a therapeutic gene that has been able to cure two severe hereditary diseases that is metachromatic leukodystrophy and Wiskott-Aldrich syndrome. Six children who had this condition are now considered cured of them.
The virus was chosen for its unique characteristic of integrating its viral DNA into regular host cell DNA with the help of an enzyme intergrase. Italian scientist had started by investigating how to use HIV as a gene carrier in the management of the above listed conditions. They took the virus and reconstructed it into a carrier for a therapeutic gene that had been created by the scientist with an aim of restoring the missing proteins.
Scientist extracted stem cells from the patients suffering from the above mentioned genetic disorders modified them before infecting them with the modified HIV that could no longer cause AIDS while leaving intact its ability to infect human cells. When the stems cells were injected back they were able to multiply and spread throughout the entire body carrying with them the therapeutic gene that eventually affected the cure. The stem cells were able to even transform the damaged cells to becoming therapeutic cells themselves.
With the success of this novel approach a way was paved for new therapies that utilize microbial genetics in management of other more common illnesses. HIV which was formula something good had actually been used for something good. In theory all enzyme deficiency diseases can actually be managed in this manner.
A worldwide killer has just been turned into becoming an irreplaceable cure for previously incurable conditions that had greatly affected people’s quality of life and limiting it altogether. It has even be suggested that HIV could be used to cure HIV using this approach by manipulating the CCRS and CXCR4 genes just like a diamond being used to cut diamonds. This goes on to show how just how significant this field is in health and medicine. The possibilities are just so amazing making the future look very bright and promising.
Despite all its positives caution should be the way to go when choosing HIV as a carrier for therapeutic genes. It’s the virus at the heart of the HIV pandemic and that does not make it less ominous. Microorganisms have been known to mutate or interact with other similar organism. It is this aspect that is frightening. What if the modified non-virulent virus mutates or interacts with other virus in the human body to become virulent once more? What if it morphs into a newer more dangerous disease? It’s this prospect that worries everybody from the FDA to would be beneficiary of this type of therapy. Its thorns keeps everybody cautious whether it good uses will remain to be risk free or not. This is not a good thing in new research frontiers.
Another virus that is also significant in health and medicine is the polio virus which exists in three serotypes that is type I, II and III. Globally there are efforts that aim to eradicate polio form human population the way small pox was eradicated. Significant strides have been made towards the eradication of polio with the confirmed elimination of type II polio in 1990 by the World Health Organization.
Microbial genetics has advised the strategy being taken by World Health Organization in its pursuit to eradicate polio ranging from vaccine development all the way to disease surveillance in the field. In the United States and other developed country the inactivated polio vaccine is used but in many other nations like in Africa the live vaccine is being used.
Countries with the largest burden of the disease are Nigeria and Pakistan. The latest case that was recorded in Nigeria was in 2012. This is where microbial genetics comes in. Samples were taken from area of occurrence and assessed. Usually the geneticist studies the viral genome to determine its ancestors or the family tree. The classifications that result from this analysis is whether the virus is wild, whether it’s orphaned or whether it’s a mutation of the vaccine antigen. This helps researcher to know the source of the prevailing epidemic at any given time.
In the case of the Nigerian epidemic the virus was discovered to be the mutation of the vaccine antigen. The antigen that was supposedly protective had changed to become virulent in the populations that had no herd immunity. This trend could in theory reverse all the gains made in the fight against polio.
Microbial geneticists under WHO advised the gradual phasing out of the live attenuated oral polio vaccine as it’s replaced by the inactivated polio vaccine which can’t mutate to cause new polio infections. The global goal for phasing out the live vaccine is 2020. Most nations are already introducing the inactivated polio vaccine in their national immunization schedules as they plan to gradual phase out the live attenuated oral polio vaccine despite its advantages of promoting herd immunity by infecting other members of the family or the community. This case also shows how significant the field of microbial genetics is in the field of health and medicine.
Another microbial organism that is loved by microbial geneticist is the bacteria Escherichia coli. We have those that are very virulent like the one that was responsible for the deaths in Europe by result in the hemolytic uremic syndrome (O157:H7) and other that are common causes for travelers’ diarrhea. E.coli also forms part of our normal flora and it has been recognized as one of the commonest causes of food poisoning and urinary tract infections especially in women.
The organism has few genes making it easy for microbial geneticists to manipulate it making scientists to refer to it as the biotech organism. A question has been asked and rightly so whether there is anything that scientist can’t do with E.coli. It has found new uses in area as varies as biofuels to insulin production
Microbial geneticists have studied the bacteria and have been able to witness a DNA repair process. This knowledge can finds its application in humans by helping scientists understand the mechanism of gene repair in human and making it even more efficient.
E.coli has also been manipulated to be used for making medicines. These medicines range from antibiotics, anticancer drugs to insulin. The cancer drug in this case is taxol. E.coli has also found use in recombinant protein production.
The area of preventive medicine is also one of the fields that have been greatly impacted by microbial genetics. Of special interest here is the recombinant DNA technology. This technology has enabled scientists to produce vaccines against conditions like Hepatitis B virus, Human papilloma virus and influenza virus infections which were previously unpreventable or uncontrollable.
This proved to be quite beneficial in easing the financial burden some of these conditions placed on the health care system. Hepatitis B Virus infection in chronic state is stills a major cause of hepatocellular carcinoma. Human papilloma virus is also a major contributor to cases of reproductive tract cancers among women. With increasing uptake of these vaccines that became possible only after DNA recombinant technology it is logical that cases of hepatocellular and cervical carcinoma will reduce.
In summary microbial genetics has opened many frontiers including one in health and medicine. Novel uses of many diseases causing microorganism are being found everyday making the future to look downright brilliant. While before most of these organisms were shunned and there was a great fight to eliminate them some of them are proving very handy in the human chase for better health and longevity.
Bibliography
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