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  • The Ebola virus: what we know, what we dont know and why we dont know.

    Aisha Belgore

  • The Ebola Virus: What we know, what we don't know and why we dont know.

    By Aisha Belgore

    Table of Contents ABSTRACT 2 ............................................................................................................................................................

    INTRODUCTION 2 ...................................................................................................................................................

    STUCTURE AND REPLICATION 4 .............................................................................................................................

    Nucleocapsid Proteins 5 .....................................................................................................................................

    Envelope Proteins 6 ............................................................................................................................................

    What we dont know about the proteins: The sGP Protein 7 .............................................................................

    Viral Protein Synthesis and ReplicaOon Within Cells 8 .......................................................................................

    TRANMISSION AND RESERVIOR HOSTS 10 .............................................................................................................

    Animal to Human Transmission 10 .....................................................................................................................

    Human to Human Transmission 11 ....................................................................................................................

    What we dont know about transmission: Droplet transmission 12 ..................................................................

    INFECTION AND PATHOGENESIS 15 ........................................................................................................................

    Receptor AWachment and Entry and Membrane Fusion Mechanisms 15 ..........................................................

    Immune System DeregulaOon 16 .......................................................................................................................

    Impairment of the vascular system 17 ............................................................................................................

    CoagulaOon 18 ...................................................................................................................................................

    Organ infecOon 19 ..............................................................................................................................................

    Death 20 .............................................................................................................................................................

    What InfecOon Routes do we not know 20 ........................................................................................................

    TREATMENT AND VACCINE 22 ................................................................................................................................

    Treatment Methods 22 .......................................................................................................................................

    Vaccine Developments 23 .................................................................................................................................

    CONCLUSION: WHY WE DONT KNOW? 24 ............................................................................................................

    Social Issues 25 ...................................................................................................................................................

    Geographic challenges 25 ..................................................................................................................................

    Economic and poliOcal Challenges 25 ................................................................................................................

    ScienOfic Challenges 25 ......................................................................................................................................

    BIBLIOGRAPHY 27...................................................................................................................................................

    1

  • ABSTRACT Ebola virus is a long filamentous virus which is the sister virus to Marburg virus and together they make up the Filovirdea family. There are 5 strains of Ebola virus: Sudan (SUDV), Reston (RESTV), Bundibugyo (BDBV), Tai forest (TAFV) and Ebola (EBOV- which was formally known Zaire Ebola). This report focuses on EBOV and the lethal Ebola Virus Disease (EVD) it causes in a human host. It also gives a detailed and in depth explanation of what is known about the virus i.e. the method used to infect its hosts, the function of its proteins, the mechanisms used to cause EVD in hosts and the effort being made by the scientific community to combat the disease. It is made evident in the report that a lot of the information available on Ebola is yet to be fully proven. Part of the purpose of writing the report are highlighting these grey areas and explain why further investigation is a challenge.

    INTRODUCTION Ebola viruses are the causative agents of Ebola Virus Disease in mammalian organisms. There are 5 species of the Ebola viruses. These are: Sudan (SUDV), Reston (RESTV), Bundibugyo (BDBV), Tai forest (TAFV) and Ebola (EBOV- which was formally known Zaire Ebola) . They all vary slightly in the sequence of their 1ribonucleic acid (RNA) and this causes them to all produce different versions of the same proteins. Because different proteins are produced they behave differently. For example, each strain of the virus can infect primates and cause the Ebola Virus Disease, however RESTV can only infect non-human primates . Of the 2 3four other strains which can infect humans, EBOV is the most lethal strain with a mortality rate varying in the range 25-90% . For this essay, EBOV will be the only strain considered. 4

    The Ebola Virus (EBOV), is a virus of order Mononegavirales, family Filovirdea, genus Ebolavirus and species Ebola . The Belgian virologist Peter Piot, who visited the area to carry out an epidemiological 5 6evaluation of the villages infected, named the genus after the closest river, the Ebola River; and the species after the country it was first discovered in, The Republic of Zaire (what is now Democratic Republic of Congo) . 7

    EBOV was first discovered in a small village called Yambuku. Its first known host was a primary school teacher who had previously been in contact with monkey and antelope meat. After a number of days he visited the hospital complaining to have symptoms identical to that of malaria which is a common illness in Zaire. The nurses at the hospital injected the malaria medicine Chloroquine into his bloodstream. As was common practice then, the needle used to administer his injection was later used for other patients that day. A fortnight later, he broke out with Ebola; his family, the people who attended his funeral and the people who also visited

    InternaOonal CommiWee on taxonomy of Viruses, 'Virus taxonomy: 2015 Release', Interna'onal Commi.ee on 1

    taxonomy of Viruses (ICTV), , [accessed 30 July, 2016].

    Richard Preston, THE HOT ZONE: THE CHLLING TRUE STORY OF AN EBOLA OUTBREAK (London: Transworld Publisher, 2

    1994), page 115.

    Jens Kunn, 'PROPOSAL FOR A REVISED TAXONOMYOF THE FILOVIRDEA: CLASSIFICATION, NAMES OF TAXA AND VIRUSES 3

    ANA VIRUS ABBREVIATIONS', Achieves of Virology, Vol.155, (December 2010), pp. 2083- 2103.

    Amanda Shaffer, 'Key Protein May Give Ebola Virus It is Opening', New York Times, 16 January 2012, pp.1-2.4

    InternaOonal CommiWee on taxonomy of Viruses, 'Virus taxonomy: 2015 Release', Interna'onal Commi.ee on 5

    taxonomy of Viruses (ICTV), , [accessed 30 July, 2016].

    Jens Kunn, 'PROPOSAL FOR A REVISED TAXONOMYOF THE FILOVIRDEA: CLASSIFICATION, NAMES OF TAXA AND VIRUSES 6

    ANA VIRUS ABBREVIATIONS', Achieves of Virology, Vol.155, (December 2010), pp. 2083- 2103.

    Carl Zimmer, 'A PLANET OF VIRUSES (Chicago and London: University of Chicago Press, 2015) pp.80.7

    2

  • the hospital the same day as him- two weeks earlier- all contracted the virus soon after. This led to the first known breakout of Ebola in 1976 . 8 9 10

    EBOV is also responsible for most recent outbreak in 2014 in West Africa which concluded on the January 14th 2016 with its final casualty in Liberia. Liberia was declared Ebola free by the Centre for Disease Control (CDC) and the World health Organisation (WHO) after going 42 days without a reported case which is double the maximum incubation time of the virus (21 days) . The 2014 outbreak originated from Meliandou, a small 11Guinea village. This was the first time this region of Africa was infected with the virus . During the outbreak 12EBOV infected 28,652 people globally (as of April 4th 2016), of this 28616 were in Sierra Leone, Liberia and Guinea which were the most affected countries. Other countries such as The United States of America, Nigeria, United Kingdom, Spain, Italy, Mali and Senegal had fewer casualties totalling to 36 cases in total . 13Sierra Leone, Guinea and Liberia- the heavily infected countries received help from global institutions and charities such as World Health Organisation and Red Cross . 14 15

    Throughout the rest of this report each section will include a descriptive subsection, explaining what we do know about the

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