The Ebola Virus

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The Ebola Virus

INTRODUCTION

The most deadly killers on this earth are too small to see with the naked eye. These microscopic predators are viruses. In my report, I will answer many basic questions concerning one of the fastest killing viruses, the Ebola virus. Questions such as "How does it infect its victims?", "How are Ebola victims treated?", "How are Ebola outbreaks controlled?" and many others related to this deadly virus.

GENERAL INFORMATION

The Ebola virus is a member of the negative stranded RNA viruses known as filoviruses. There are four different strains of the Ebola virus - Zaire (EBOZ), Sudan (EBOS), Tai (EBOT) and Reston (EBOR). They are very similar except for small serological differences and gene sequence differences. The Reston Strain is the only one which does not affect humans. The Ebola virus was named after the Ebola river in Zaire, Africa after its first outbreak in 1976.

STRUCTURE

When magnified by an electron microscope, the ebola virus resembles long filaments and are threadlike in shape. It usually is found in the form of a "U- shape". There are many 7nm spikes which are 10nm apart from each other visible on the surface of the virus. The average length and diameter of the virus is 920nm and 80nm. The virons are highly variable in length (polymorphic), some attaining lengths as long as 14000nm. The Ebola virus consists of a helical nucleocapsid, which is a protein coat and the nucleic acid it encloses, and a host cell membrane, which is a lipoprotein unit that surrounds the virus and derived form the host cell's membrane. The virus is composed of 7 polypeptides, a nucleoprotein, a glycoprotein, a polymerase and 4 other undesignated proteins. These proteins are synthesized by mRNA that are transcribed by the RNA of the virus. The genome consists of a single strand of negative RNA, which is noninfectious itself. The order of it is as follows: 3' untranslated region, nucleoprotein, viral structured protein, VP35, VP40 glycoprotein, VP30, VP24, polymerase(L), 5' untranslated region. HOW IT INFECTS

Once the virus enters the body, it travels through the blood stream and is replicated in many organs. The mechanism used to penetrate the membranes of cells and enter the cell is still unknown. Once the virus is inside a cell, the RNA is transcribed and replicated. The RNA is transcribed, producing mRNA which are used to produce the virus' proteins. The RNA is replicated in the cytoplasm and is mediated by the synthesis of an antisense positive RNA strand which serves as a template for producing additional Ebola genomes. As the infection progresses, the cytoplasm develops "prominent inclusion bodies" which means that it will contain the viral nucleocapsid that will become highly ordered. The virus then assembles and buds off from the host cell, while obtaining its lipoprotein coat from the outer membrane. This destruction of the host cell occurs rapidly, while producing large numbers of viruses budding from it.

WHAT IT INFECTS

The Ebola virus mainly attacks cells of the lymphatic organs, liver, kidney, ovaries, testes, and the cells of the reticuloendothelial system. The massive destruction of the liver is the trademark of Ebola. The victim looses vast amounts of blood especially in mucosa, abdomen, pericardium and the vagina. Capillary leakage and bleeding leads to a massive loss in intravascular volume. In fatal cases, shock and acute respiratory disorder can also be seen along with the bleeding. Numerous victims are delirious due to high fevers and many die of intractable shock. SYMPTOMS

During the onset of Ebola, the host will experience weakness, fever, muscle pain, headache and sore throat. As the infection progresses, vomiting (usually black), limited kidney and liver function, chest and abdominal pain, rash and diarrhoea begin. External bleeding from skin and injection sites and internal bleeding from organs occur due to failure of...
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