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Why HIV Cannot Be Cured

Health Care Presentation Notes on why AIDs is incurable / very hard to treat due to its virus adoptability in word/ .doc/ .ppt/ .pdf format

VIRAL RESISTANCE: STILL A MAJOR PROBLEM :

Depending on the stage of the disease, between 100 million and 10 billion new viral particles can be produced in an HIV-infected individual each day. This process of multiplication is accompanied by repeated mutations that give rise to strains that can ultimately undermine the long-term efficacy even of drugs that are highly effective initially.

Of the total number of HIV particles present in the body of an infected person at a given time, an average of 107 are still in the provirus stage and about 106 are in the form of infectious viral particles. Each of the latter can give rise to about 102 to 104 new viral particles in an infected host cell, thus giving a total of between 108 and 1010 new viral particles per day, depending on the stage of the disease. However, the viral particles multiply with such a high mutation rate that it is estimated that every position on the viral genome is incorrectly copied once each day. The great genetic variability of the virus results in a broad range of strains, some of which differ from each other in only about 100 of the total of 9500 nucleotides that make up their genome, whereas others differ in more than 1000 nucleotides.


As the nucleotide sequences contain the genetic code for the viral proteins, such differences affect the protein composition of the viral structures (in particular the envelope glycoproteins) and thus also the biological activity of the viral strain concerned.

HIV is thermolabile, being inactivated in 10 min. at 50oC and in seconds at 100oC. At room temperature (20-25oC), in dried blood it may survive for upto 7 days. It withstands lyophilisation. The virus in lyophilized blood products can be inactivated by heating at 680C for 72 hours and in liquid plasma at 60oC for 10 hours. HIV is inactivated in 10 min. by treatment with 50% ethanol, 35% isopropanol, 0.5% Lysol, 0.5% paraformaldehyde, 0.3% hydrogen peroxide, 1% nonidet p40, or 10% household bleach. It is also inactivated at the extremes of pH (pH 1 and 13). Bleaching powder or household bleach are effective for surface decontamination. For treatment of contaminated medical instruments, a 2% solution of gluteraldehyde is useful.


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