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| | According to Greek mythology, when curious Pandora opened a forbidden box she set loose all the miseries and evils known to the world. One of them was undoubtedly the virus the very name of which is Latin for slime, poison and stench (Eigen, 1993 p. 42). | |
 | | Scientists do not precisely know the origin of viruses but some speculation suggests that viruses might have originated either as primitive molecules that invaded living cells or as viral genes which broke away from cells and became independent, parasitic-like agents. Viruses can infect most living things including plants; they lie dormant until they can find a living host to invade. In humans, viruses are known to cause a variety of illnesses, ranging from the common cold to smallpox, polio and HIV/AIDS. During the early research of viruses, scientists were "puzzled by the high mutation rates they observed: the magnitudes indicated that viruses must evolve more than a million times faster than cellular microorganisms" (Eigen, 1993 p. 42). | Viral particles are so small that 100,000 gathered together are scarcely visible (and until the widespread use of electron microscopes beginning in the 1930s, viruses could not been "seen"). Viruses have a genetic program whose purpose is to multiply inside its host. "All viruses, including HIV, are primitive creatures: tiny bundles of genes wrapped in protein, quite unable to reproduce until they've infected their chosen host" (Caldwell, 1993, p. 62).
HIV has morphological, biological, and molecular similarities to viruses affecting animals, but until now not known to affect humans. These viruses are "retroviruses" -- ones that are regressive -- they "go backward." A retrovirus changes the original molecular structure of its host cell... These cells become HIV cells forever (McKenzie, 1991, p. 19). | | | The specific target of retroviruses is the immune system, and that is what makes this kind of virus so deadly. Dr. Haseltine of Harvard said: "Once the infection is in, the damage has been done" (Haseltine, 1994, p. 7). Unlike virtually any other virus, HIV has the capability of existing in the cell's genome in the latent state so that a substantial amount of the virus is in a form that cannot be recognized by the immune system. Actually we now know that the term "latent" is not quite correct. HIV is constantly reproducing; it never stops. But because it hides within the cells' DNA (covertly copying itself every time the cell divides) it remains undetected. Thus the misnomer "latent" is still used in AIDS terminology. | |  | | | In the case of HIV/AIDS, the virus signals replication of itself in other cells: "allowing the virus to use the human cell as a kind of virus factory" (Strecker, 1986). Retroviruses must grow inside of living tissue which requires that there be a living human or animal for them in which they can replicate. It is a virus' very nature to make itself proliferate in the infected host cells (which continue to multiply). | | | But that is not the case with HIV. Its mission is to destroy its host cells. That is why it was so difficult for scientists at first to grow this peculiar virus in human tissue sample; every time HIV was introduced, the tissue would be dead in a few days when the scientists came back to view it. Basically there would be only debris with very little virus and no living cells. This phenomenon greatly worried researchers, for without enough retrovirus to study, how were they going to discover its mechanism and its mystery? Scientists had never had such a challenge before. That is another reason why the problem of HIV/AIDS was and continues to be so difficult to decipher and master. AIDS has the potential for killing millions of humans before scientists and medical researchers expect to discover how the virus' mechanism works and consequently, how it can be controlled. It is now accepted that there most likely will be many new challenges of this magnitude from new HIV/AIDS mutating strains and similar retroviral organisms in the future too(see Table36). Scientists have been able to isolate many viruses and either control or destroy them with medical therapies and preventive vaccines. But not so with HIV/AIDS. | |
What is also amazing about HIV is its viral complexity and ability to constantly mutate. As a result it is proving to be difficult to observe and understand, let alone to find ways of destroying it:
The genome of a single-strand RNA virus such as HIV, which comprises only 10,000 nucleotides, is small and simple compared with that of most cells. Yet from a molecular standpoint, it is unimaginably complex. Each of those nucleotides contains one of four possible bases: adenine, uracil, guanine or cytosine. The unique sequence specified by the genome of HIV therefore represents just one choice out of 4 10,000 possibilities -- a number roughly equivalent to a one followed by 6,000 zeroes (Eigen, 1993 p. 42). | |  | | | That means that instead of being a single, simple virus, there is a field effect of viruses, and that explains why every virus of HIV/AIDS growing in different human tissue, will vary by some degree in every person, like a genetic, viral fingerprint: "HIV is genetically unstable... in just a few years within a single individual, the virus can transmogrify itself so often that the human immune system can no longer keep up with it" (Caldwell, 1993, p. 62). New exposure to different sub-strains of HIV can change the virus in a person already infected. It is the basic nature of retroviruses to recombine and then reproduce constantly. Because HIV, with its greater hypervariable and variable positions, mutates so fast and so radically, vaccines will probably never be produced that can keep up with HIV's ability to avoid detection. There is some recent research that suggests that it theoretically might be possible to devise some vaccine, but many AIDS authorities do not agree vaccines could ever be effective (it is conceiveable that one day the millions of different HIV variants might mutate out of existence or transmogrify into a more benign form). There are two well-known HIV viruses -- HIV-1 and HIV-2 with more likely to develop. The myriad of viral variants mutate within groups which some researchers refer to as "clades" (Greek for branches). Currently it is reported that there are seven clades (or sub-types) with many different HIV strains in each clade (HIV-1 varies by as much as thirty percent between clades and as much as twenty percent among each clade)(Sullivan, 1994). | | | Most research efforts presently concentrate on the HIV-1 strain which is more common in the United States and other western countries because pharmaceutical companies are concentrated there and invest the greatest amount of research dollars (Essex, 1993). Currently it is only the richer, developed nations that are able to afford the expensive treatments (but not cures) and provide a modicum of care to people living with AIDS. While this fact might be advantageous for adolescents fortunate to live in the United States and Europe, it is disadvantageous to the majority of adolescents in the developing world who may be infected by many of the different strains of HIV/AIDS. Additionally, as the research will point out in this report, HIV/AIDS knows no borders. Whatever strain of HIV attacks a developing country today will later attack all other populations as well (because any possible vaccine could only be effective for one specific strain and would offer no protection from different strains). Therefore, persons with AIDS (PWAs) in the United States might have a form of HIV-1 that may differ up to thirty percent from the strain in an Africans or Asians. | |
And the strains are constantly mutating. Scientists have a tremendous task to try to keep up with the ever changing virus in the hope of developing a preventive or therapeutic vaccine. A truly effective vaccine must be able to protect the body against all of the possible strains and there are few researchers who believe that is likely to occur.
With so many mutations changing HIV constantly, there will be no "sure cure." Adolescents, in particular sexually-active teens, must be made aware of this scientific reality. |
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