Emerging Viruses-Aids & Ebola - By Leanard ... - preterhuman.net

deadly foreign DNA, which then commands the cell'sreproductive machinery to produce more viruses rather thanhealthy new cells.This switch in reproductive control is accomplished partlybecause RNA and DNA are very much alike. The only differencebetween them is the substitution of one sugar-linked molecule,called uracil in RNA, for another one, called thymine, in theDNA (see figs. 6.1 and 6.2).As shown in fig. 6.3, AIDS viruses have a special attraction forT4 lymphocytes. These blood cells possess special magnetlikeCD4 receptors. These attachments normally serve to detect andhelp destroy foreign invaders, called antigens, via a compleximmunological defense system. These CD4 receptors bind to aportion of HIV's outer envelope known as the gp 120 antigen.The CD4-gp 120 interaction allows the AIDS virus to betransported across the lymphocyte's protective outer membrane,and once inside the cell, the viral envelope opens releasing theunique RNA and special enzymes into the human cell. [1]Then, by means of the special reverse transcriptase enzyme-sonamed because it prompts the "reverse" process of copying DNAto RNA - the RNA code is copied to produce a new "proviralDNA" strand. This enzyme is technically called RNA-dependentDNA polymerase. It directs the cell to produce a DNA genesequence from the viral RNA template, the exact opposite ofwhat normally occurs in the non-infected cell.This DNA provirus then enters the cell's nucleus where geneticmaterials are stored. Here the provirus is inserted into the host'snormal gene sequence through the work of another uniqueenzyme known as viral endonuclease. The endonuclease enzymefunctions like a pair of scissors. It cuts open the cell's normalDNA strand allowing the newly formed provirus to be inserted.Later, during normal cell operation, the provirus directs new viralproteins to be produced, which eventually bud off the cellforming new viruses. [1]This is the theory Gallo advanced fIrst in 1972 during the "waron cancer" in order to explain retrovirus related cancers such aslymphoma, leukaemia, and sarcoma. Twelve years later, headvanced the same theory to explain AIDS.- - - - -Fig 6.1 - The Molecule Structures Compriising Nucleic AcidsRNA and DNA - Life's Building Blocks:PENDINGSource: Asimov I. The Intelligent Man's Guide To Science.Volume II, The Biological Sciences. Basic Books, 1960. pp.526-527.