Free Cure The World Of Cholera With A Potent Bacteriophage Essay Example

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Abstract

Although cholera is a curable disease and was one of the earliest studied infections it still causes a number of deaths in places where access to fresh drinking water is a problem. From 2011-2013 over one million people were affected in different parts of the world with nearly 80% of the cases which can be treated (WHO, n.d.). Briefly, cholera is caused by the Vibrio cholerae and the cholera toxin causes diarrhea and vomiting in the victim. If the microbe goes back into the water it can be taken up again or be taken up by an unsuspecting person or be trapped in zooplankton or shellfish then later get taken up by an unsuspecting person (Charles, 2011). Although we understand the cause, the biological mechanism and have a way to treat it we have very few ways to eradicate cholera. Currently, better water purification through chlorination, boiling or filtration is seen as the cheapest and easiest method to prevent this disease (WHO n.d.). Vaccinations have only had limited use in affected areas and in order for a vaccination to work there has to be substantial number of people to be vaccinated (Graves, 2010). Although this could be a cure it also is quite expensive when the disease might only affect a small population. In this proposal we will try to find a cheap effective bacteriophage that can turn off cholera before multiplying and infecting a new host/vector.
Keywords:Bacteriophage,, cholera toxin, eradication, Vibrio cholerae

Specific aims

We aim to develop a new bacteriaphage that will inhibit the normal functions of the V. Cholerae. This approach using molecular biology can eliminate the V. Cholerae bacteria cheaply and quickly.

Biological and Historical Background of Cholera

Although Cholera is present mainly in developing countries or after natural disaster it was fairly common in England not so long ago. The thought in 1832 was that cholera spread through the air or ‘miasma’. It was not until Dr. John Snow proposed the theory of microbes 22 years later that people started to find a solution to this pandemic (Johnson, 2006). One of the early solutions was to make a better sewers and drinking water. However, at the time though good drinking water was in scarce supply and beer and wine were the prefered beverage. This was also noted by Snow that none of the brewery workers conducted cholera. In the process of fermentation (increase in alcohol, low pH, and chemistry), inoculated and outcompeted with the cholera (Johnson, 2006).
The V. Cholera is a gram negative bacteria that has a flagella that allows it to propel through the mucus membrane in the gut and a pilus that allows it to attach itself to the small intestine and colonize (Charles, 2011). In the bacterial genome it has genetic coding instructions for proteins that are involved in the virulence of the bacteria (Waldor 1996, Heidelberg 2011). Nontoxic bacteria exist however but can acquire toxicity through temperate bacteriophage (detailed below). The V. Cholera is toxic effect is mainly from the oligomeric cholera protein which is endocytosed and goes through a multistep mechanism which in the end causes chloride channel proteins to take up chloride and release water, sodium, potassium, and bicarbonate leading diarrhea in infected people (Charles, 2011).
As the V. Cholera bacteria toxin can be turned on by temperate bacteriophages a similar mechanism might enable the toxic species to be turned off by an engineered bacteriophage. Bacteriophages are viruses that infect and replication within the bacterium. Once inside the bacterium they can replicate or be lysed. Bacteriophages are mainly present in water bodies and are very common in seawater (e.g. the same place where V .Cholera lives) (Charles, 2011). Additionally, they have been used as antibacterial agents since the 1920s and since 1915’s early bacteriophages were discovered to act against cholera. Specifically, bacteriophage CTXφ contains all the genetic material that is needed for V. Cholerae to produce the toxin and infect people e.g. CT toxin and Pilus needed to attach to wall. There have been some unsuccessful attempts to find this bacteriophage and neutralize it thus neutralizing the Cholera (Charles, 2011).

Proposal

I propose a new bacteriophage to neutralize cholera. This bacterium will not only go after the cholera toxin it will also contain material to inhibit use of the flagella. We are planning not only to take away its teeth we are taking away its legs. Firstly, I will look at the genetic code of different strains of V. Cholerae and bacteriophage CTXφ. It has already been proposed to use the bacteriophage to lyse the V. Cholerae (Waldor, 1996) we are proposing to inactivate it through several mechanisms. We will incorporate the new research on the coding sequence of the flagella (Zhu, 2013). Then using modern molecular biology techniques I will encode inhibition elements and produce a self-replicating bacteriophage which will be able to turn off both the filament and toxins of the V. Cholera. We will test this on different strains of the V. Cholerae bacteria and determine whether the bacteriophage’s potency. If it is successful this bacteriophage can be added to contaminated waterways at different periods of time. As bacteriophage CTXφ are not harmful to humans and this particular one is specific for V. Cholerae it should not pose a risk. Over time the hope would be that the V. Cholerae bacteria will not be able to produce specific structural elements like flagella and be eradicated.

Conclusion and Potential Outcomes

Cholera has killed millions of people and we are hoping to eradicate it by using an old technology, bacteriophage. This technology offers not only a cheap and effective way of eradicating this cholera it also could be used for other waterborne infections in the same way. If we could recode the bacteriophage genome to include inhibitory elements to stop the core machinery of the microbe we will make the world a safer place.

References

Charles RC & Ryan ET (2011). Cholera in the 21st century. Current Opinion in Infectious Diseases 24 (5): 472–7.
Heidelberg, J. F., Eisen, J. A., Nelson, W. C., Clayton, R. A., Gwinn, M. L., Dodson, R. J., & Fraser, C. M. (2000). DNA sequence of both chromosomes of the cholera pathogen Vibrio cholerae. Nature, 406(6795), 477-483.
Gardel C. L. & Mekalanos J. J. (1996). Alterations in Vibrio cholerae Motility phenotypes correlate with changes in virulence factor expression. Infect. Immun. 64, 2246–2255
Graves, P. M., Deeks, J. J., Demicheli, V., & Jefferson, T. (2010). Vaccines for preventing cholera: killed whole cell or other subunit vaccines (injected). The Cochrane Library.
Johnson, S. (2006). The ghost map: the story of London's most terrifying epidemic--and how it changed science, cities, and the modern world. Penguin.
WHO, (n.d), Global Health Observatory Data Retrieved from: http://www.who.int/gho/epidemic_diseases/cholera/en/
Waldor, M. K., & Mekalanos J.J.. Lysogenic conversion by a filamentous phage encoding cholera toxin. Science 272.5270 (1996): 1910-1914.
Zhu, Shiwei, Seiji Kojima, & Michio Homma.(2013) Structure, gene regulation and environmental response of flagella in Vibrio. Frontiers in microbiology 4 .