Free Course Work On Microbiology

Published: 2021-06-22 00:42:19
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Liver is an important organ in the digestive system. The selected infection is hepatitis C. This viral infection affects the liver and then results in the liver enlargement. This form of hepatitis is one of the major challenges worldwide since its discovery and this could be attributed to the absence of a vaccine against the viral infection. Another important contributory factor is that of the prolong period of inactivity of the virus within the host before clinical manifestation. These all contribute to the level of destruction of the liver caused by the virus.


The main aetiology is by the hepatitis C virus. However, there are different modes of transmission which include:
Blood-to-blood contact which serve as the highest contributing factor. Blood contact through sharing or re-use of injecting equipment are the source of contact.

Puncture sites or surfaces that can become contaminated with blood split

Blood transfusion of contaminated blood or products
Tattoos and body piercing
Blood to mother transmission
Share of razor blades, clippers or other sharps
Virulence factors

The main virulence factor in the hepatitis C virus is yet to be delineated however recent evidence has shown that HCV p7 which is a viral protein from the virus tend to form some form of ion channels which may later be targeted by antiviral compounds (Stelmann et al, 2007). It was also found that the protein is essential for efficient assembly and release of some virions that are infectious (Stelmann et al, 2007). The protein was also found to be involved in the late phase of the viral replication hence indicating that this protein may actually be the virulence factor which helps in modulation of viral fitness, persistence and then pathogenesis within the host (Stelmann et al, 2007)


Hepatitis is somehow similar regardless of the aetiology. Steatosis, bile duct injuries and portal lymphoid aggregates are the changes that differentiate hepatitis caused by hepatitis C virus from others. There are two main phases of presentation which are the acute and chronic phases. The duration and features clearly distinguish the phases. Infection with the virus initiates some form of body immunity; it is this that now leads to inflammation of the liver. The consequences of the inflammation are that, it is a prolonged condition. It also leads scarring of the tissue of the liver which is termed liver cirrhosis. The implication of this is that the liver will not be able to perform its normal function, hence various complications and death in some cases.

Outcome of disease

Most patients (About 75 per cent) usually have no symptoms when infected with the virus but the signs and symptoms become clinically manifested at a later period. Others present with acute phase symptoms. Those include: fatigue, fever, jaundice, and loss of appetites. It is after 6 months that people later present with various signs and symptoms. In the chronic form, signs and symptoms include: tiredness, loss of appetite, nausea, fever, joint pain, vomiting, depression, and soreness below ribs in the upper right side of the stomach.


Drugs such as ribavirin and interferon when used as a combination therapy or changing the interferon to pegylated interferon help manage the infection. This must start immediately as the infection is being diagnosed. Pegylated type of interferon is also found to be good. Patient must also eat healthy food and avoid smoking, and alcohol.


Prevention can be achieved by provision of various guidelines and policies in the hospital, educating the youth right from childhood on the dangers of injection drug use or sharing of sharps and provision of measures to prevent unscreened blood transfusion.


An example of a bacterial exotoxin is the Botulinum toxin is an exotoxin produced by Clostridium botulinum. It is made up of a molecule that is synthesized as a single Chain and the chain is later cleaved to form two chains (dichain). The new dichain has a molecule with a disulfide bridge. The light chain of the dichain is of 50kD while the heavy chain is of 100kD. The light chain is similar to tetanus toxin and exhibit proteolytic activities. The amino acid make up of light chain is 448 while that of the heavy chain is 1280. There are seven known types of which are describe with A-G types. The heavy chain has cholinergic specificity which makes it binds to presynaptic receptions. The botulinum is a phage encoded neurotoxins and has a binding domain as a B-subunit. The binding domain binds to the neuroreceptor gangliosides on the cholinergic neurons. This is what irreversibly causes inhibition of the stimulatory neurotransmitter known as acetycholine. Once this happens, it results in the flaccid paralysis and death.

In the world of vaccination, antidote is mostly produced when the scientist has fully understood and describes the nature of the infection and the microorganism implicated. This is the case of the botulinum vaccine. This vaccine that has been produced is yet to be released for public use. Pentavalent botulinum toxoid vaccine is the only one that has been produced that is available for human use. This vaccine is basically used by those that are involved directly with the bacteria. Those people are laboratory personnel and military personnel that are at high risk of infection.

The vaccines produced are based on the understanding of the structural mechanism of action of the toxin. What is usually done during the manufacturing of the vaccine is to place the toxin under laboratory fermentation to extract the protein and this is then later diluted with the human serum albumin. The product of the fermentation is then freeze. The important consideration before use is the reconstitution and the use must be within 4 hours of the reconstitution process to prevent disintegration of the product.

Recombinant DNA technology

Recombinant DNA technology is applicable to different fields such medicine, biotechnology, agriculture etc. An important technique of the technology is the genetic modification of crops. Genetic modification is a great advancement in genetic engineering and this has help achieved a modern modes of plant breeding. It has contributed greatly to the fight against low yield caused by pest and weed. It has led to improvement in nutritional component of some crops.

The technology is all about bringing about specified changes to the parent crop DNA structure with advanced techniques and instrument. Rice genetic modification shed light on the diversity and function of the rice gene and help developed a better variety that has a better nutritional value within the edible parts when compared to the normal rice edible parts.

Golden rice is a product of genetically modified crop. It is a new variety rich in vitamin A when compared to old rice. The production of this enhanced type was achieved through the introduction of beta-carotene gene into the previous types of rice to make the edible part more nutritious. The new golden yellow colour is one of the effects of the modification. This shows the colour of the introduced beta-carotene, which could be compared to the similar colour, found in carrot.

Golden yellow rice technology was based on creation of a simplified carotenoid biosynthesis pathway. It was created in such a way that there are enzymes production in the endosperm and this help catalyse the beta-carotene from geranylgeranyl diphosphate. The rice was transformed with two beta-carotene biosynthensis genes (, 2011). Only two of those genes were needed to achieve the goal of production of the beta-carotenene. The process of encoding the gene was achieved by conjugation process. The procedure of conjugation is usually achieved with some forms of bacteria activities that allow the transfer of product from one point to other. The implication of this is that there's improved value as regards to those golden yellow rice.

References 2011. The science behind Golden rice. Filling in the gaps [Online].
ThinkQuest. 2011. Techniques. [Online]
Stelmann E, Penin F, Kallis S, Patel AH, Bartenschiager R, & Pletschmann T. 2007. Hepatitis C virus p7 protein is crucial for assembly and release of infectious virions. PubMed. PLoS Pathog. 2007 Jul;3(7):e103. [Online]

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