‘virus’

Overview of Virus (part 4)

Thursday, January 14th, 2010

overview of virus8. Role in research

The main goal of biologists has been the molecular study of viruses and their interaction with the host cell. The study of bacteriophage replication in bacteria discovered the existence of messenger RNA, carrying the genetic code of DNA needed for protein synthesis. Studies with these viruses have also been instrumental in defining the biochemical factors that start and end the use of genetic information. Knowledge of the mechanisms of control of viral replication is critical to understanding the biochemical events in higher organisms.

The viruses are useful as model systems for studying the mechanisms that control genetic information, because in essence are small pieces of information. This allows scientists to study replication systems simpler and more manageable, but that function on the same principles as those of the host cell. Much of the research on the virus replicative pretends to know the mechanism to find and how to control growth and eliminate viral diseases. Studies on viral diseases have greatly contributed to understanding the body’s immune response against infectious agents. Studying this response have been thoroughly described serum antibodies and the secretions of mucous membranes, which help the body eliminate foreign elements such as viruses. Now, the scientific interest is focused on research designed to isolate certain viral genes. They could clone to produce large quantities of certain proteins, which would be used as vaccines. (more…)

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Overview of Virus (part 3)

Wednesday, January 13th, 2010

overview of virus5. Propagation

Viruses are spread from person to person, causing new cases of the disease. Many of them, as those responsible for influenza and measles, are transmitted by inhalation, through its dissemination in the infected droplets emitted by coughing and sneezing. Others, like those that cause diarrhea are spread by fecal-oral route. In other cases, the spread is through the bite of insects, such as yellow fever and arboviruses. Viral diseases may be endemic (specific to one area), affecting susceptible individuals, or epidemic, which appear in waves and attack much of the population. An example is the emergence of epidemic flu worldwide, almost always once a year.

6. Treatment

The treatments against viral infections are often not entirely satisfactory, since most of the drugs that kill viruses also affect cells in which they play. The alpha-adamantanamine is used in some countries to treat respiratory infections caused by influenza A and isatin-beta-thiosemicarbazone, effective against smallpox. Certain substances similar to precursors of nucleic acids may be useful against severe herpes infections. (more…)

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Overview of Virus (part 2)

Tuesday, January 12th, 2010

overview of virus
3. Replication

The virus, lacking the enzymes and metabolic precursors necessary for its own replication, they must obtain them from the host cell they infect. Viral replication is a process that includes several separate synthesis and subsequent assembly of all components to give rise to new infectious particles. Replication is initiated when the virus enters the cell: cellular enzymes remove the cover and the DNA or RNA is contacted with the ribosome, directing the synthesis of proteins. The virus nucleic acid autoduplicates and, once synthesized protein subunits that form the capsid, the resulting components are assembled into new viruses. A single virus particle can cause a progeny of thousands. Some viruses are released by destroying the infected cell, and yet leave the cell without destroying it by a process of exocytosis that leverages own cell membranes. In some cases the infection is ’silent’, ie the viruses replicate inside the cell without evident harm.

RNA-containing viruses are unique replicative systems, since the RNA autoduplicates without the involvement of DNA. In some cases, viral RNA functions as messenger RNA, and replicates indirectly using the ribosomal system and the metabolic precursors of the host cell. In others, the virus carried in the cover-dependent RNA enzyme that directs the synthesis process. Other RNA viruses, retroviruses, may produce an enzyme that synthesizes DNA from RNA. Formed DNA then acts as the viral genetic material. (more…)

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Overview of Virus (part 1)

Monday, January 11th, 2010

overview of virus
1. Introduction

(Latin for ‘poison’) organizational entities composed only of genetic material surrounded by a protective envelope. The term virus was used in the last decade of last century to describe the disease-causing agents smaller than bacteria. Lack of independent living but can replicate inside living cells, often damaging to his guest in this process. The hundreds of known viruses are the cause of many different diseases in humans, animals, bacteria and plants.

The existence of viruses was established in 1892, when Russian scientist Dmitry I. Ivanovsky, found microscopic particles, known later as the snuff mosaic virus. In 1898 the Dutchman botanist Martinus W. Beijerinck called these particles infectious virus. A few years later, viruses were found growing on bacteria, which are called bacteriophages. In 1935, the American biochemist Wendell Meredith Stanley crystallized the snuff mosaic virus, showing that consisted only of genetic material called ribonucleic acid (RNA) and an envelope protein. In the 1940s the development of electron microscopy enabled the visualization of the virus for the first time. Years later, the development of high-speed centrifuges able to concentrate and purify. The study of animal virus reached its peak in the 1950s with the development of cell culture methods, support of viral replication in the laboratory. Then they discovered many viruses, most of which were sampled in the 1960s and 1970s, in order to determine their physical and chemical characteristics. (more…)

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