What is a computer computer computer virus ? Why argon they so nasty to controlViruses are microscopic particles of 20-300nm in size , give intra cellular telephoneular parasites they loafer throw up only by invading and taking over other cells as they escape the cellular machinery for self-importance reproduction . Host range accommodates a wide con gradation of animal and plants There are viruses which offer infect bacterium and they are called batceriophage . A complete virus particle is called virion consisting of its uncomplicated nucleic acid (either ribonucleic acid or desoxyribonucleic acid ) and a protein come out called capsid . Viruses with DNA as transmittable stuff are called DNA virus ( eg herpes virus virus or Adenovirus etc ) and those with RNA as genetic material are called RNA viruses ( e .g : Foot an d Mouth infirmity virus , SARS virus human immunodeficiency virus etc . Virus encoded proteins strain the capsid . The nucleic acid and the capsid together termed as nucleocapsid . authoritative viruses have a membrane or envelope screen the nucleoacpsid and they are called enveloped viruses . The envelope is ordinarily of glycolipid and the lipid membrane itself and some(prenominal) carbohydrates present are altogether entertain-coded (The grippe virus and HIV use this strategy to thwart the resistive formationSince viruses use the machinery of a server cell to reproduce and reside within the armament cell , they are vexed to eliminate without killing the force cell . Viruses used antithetical mechanisms to evade the immune organization of the host cell . The approximately commonly used strategies include antigenic variation , antigenic shift and botch . Influenza virus uses both antigenic shift and antigenic drift to evade the immune system .
antigenic variation can occur through cardinal broadly defined genetic processes : gene mutation , recombination , and shift results in pathogens that are immunologically distinguishable from the parental strains there by escaping the immune system of the host .Antigenic shift involves between dickens different subtypes of the same virus coinfect a single cell and exchange RNA segments to form a new subtype . Antigenic drift is by changing the surface protein mainly haemagglutinin and Neuraminidase proteins in case of influenza virus . Mutations in the RNA or DNA causes change in the surface protein and host immune system fails to identify the viral proteins and this will facilitate the viral persistence in the host cell and making it voiceless to controlReferenceds Virology , David M .Knipe , Peter M Howley , Diane E Griffin , Robert A Lamb , Malcom A Martin , Bernard Roizman , Stephan E Stratus , Source Lippincott Williams Wilkins (LWW , fifth edn , 2007 . PAGEPAGE 1...If you want to get a full essay, order it on our website: OrderCustomPaper.com
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