The Ebola Virus: What is a virus ?

HOME CONTACT INFORMATION DISCLAIMERS LINKS FOREWORD concept of the website AIMS AND METHODOLOGY INTRODUCTION The violent world of Biosafety level 4 viruses WHAT IS A VIRUS? Explains what a virus is THE EBOLA VIRUS The nature of the beast THE LIFECYCLE OF THE EBOLA VIRUS The Pathology of the virus - not for children VARIATIONS OF THE EBOLA VIRUS Different Strains currently known RESERVOIR SPECIES THE HIV VIRUS Ebola / HIV comparison HISTORY OF OUTBREAKS Summary and Table TREATMENT AND CURRENT STAGE OF RESEARCH Can Ebola be used as a biological weapon ? THE TROPICAL RAINFOREST AND ITS DESTRUCTION Link between deforestation / species extinction and Ebola? GIS ANALYSIS CONCLUSION		the structure of a virus What is a virus? Viruses are found in almost all parts of the earth, including the Arctic and infect nearly every form of life including unicellular organisms to human beings. First, it is important to know what exactly a virus is. A virus is a small capsule made of lipid membranes enclosing certain proteins. This capsule contains usually one or two strands of either RNA (Ribonucleic Acid) or DNA (Deoxyribonucleic Acid). DNA and RNA are long molecules, which contain genetic codes or information. This is distinguishing feature of viruses in comparison to the host, which has both DNA and RNA. Luckily, the virus is composed of sub-units, or copies of similar proteins, which reduces the amount of genetic material needed and consequently the number of possible mutations. The virus exists, seemingly, for only one purpose - to replicate. Replication as the prime directive for the virus The most significant property of viruses is that they are not self reproducing as are all living organisms on the earth. Even unicellular life forms reproduce themselves by cell division. The virus needs the presence of a host to replicate. It uses the machinery, that is the ribosomes of the host cell, in order to replicate. One more distinguishing feature of the virus is that it uses only its nucleic acid (RNA or DNA) to replicate, in comparison to the host cell that reproduces from all its components. This can be explained simply The virus never arises from a pre-existing virus while the host cell always arises directly from a pre existing cell. The individual components of the virus are synthesised separately and then assembled into a mature virus particle. General size of a virus A virus is extremely small, being measured in nanometers (10^-9 meters). They can be seen only with the help of an electron microscope. Viruses are also classified on the basis of shape. Icosahedral form, which can be approximated as a sphere. Rhabdoviruses (rabies), which are bullet like in shape Filoviruses, which are long and thread-like. Is the virus a life form? The virus cannot be classified as being either alive or dead and hence is usually classified as a “life form”. Method of Replication The virus outside a cell lies dormant and waiting and when possible it attaches itself to a host cell. The host cell recognises the virus attachment and enfolds the virus and allows the virus to enter into the interior of the cell. The virus having gained accesses to the interior of the cell ‘switches on’ and begins to replicate. The virus uses the material from the cell to replicate and continues making copies of itself till the cell is literally crowded with viruses and at this point either the viruses start moving out of the cell or the cell bursts. The process of replicating continues within that cell till the cell is exhausted, consumed and destroyed. And so the process goes on. If enough cells are destroyed, the host dies. It is not in the best interest of the virus to kill its host because then the virus may also die with the host, unless it can make the jump to a new host fast enough.