What AIDS Is (978 hits)
Category: Science & EnvironmentalRating: 1.11 on 19 reviews (Rate this item) (V)
Submitted by Nom DeGuerre (View user info) at 2006-01-02 08:18:04 EST
This article began life as an essay for my tutor, with the title 'What Is AIDS And Where Did It Come From?', but I thought it would be interesting for other people, so I've made it less 'sciency', and here it is with the extraordinarily imaginative title, 'What AIDS Is'. Its rather long, so you may just wish to skim read it or read only bits of interest. Or you may not want to bother at all. One last thing to say is that the references are
a) Not superscript, but I have tried (though probably missed many) to put them in brackets e.g. (1) for clarity
b) given briefly at the end because to put them in full would have been ridiculously space-consuming. If you would like a more detailed bibliography, I can email it to you.
AIDS
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In the first few months of 1981(1 ), a series of previously healthy young men began reporting to doctors in New York and California with various serious illnesses and no known cause. Before long, cases were reported throughout America and much of Europe. At the time, very little was known about these strange cases, but over the past 26 years an ever-increasing degree of understanding has been emerging and helping to explain the origins, causes and potential cures for what has become known as the Human Immunodeficiency Virus , or HIV. It is this virus which is now generally accepted as the cause of Acquired Immune Deficiency Syndrome(2) (AIDS) - the once-mystery infection.
Before its origins can be fully understood, it is necessary to have a clear idea of exactly what AIDS is and how it arises in humans. Given the huge volumes of evidence(1) (discussed later) to support the claim that HIV is the direct cause of AIDS, it is almost impossible to conduct a study of AIDS without looking at HIV.
HIV is a retrovirus - a virus that is able to synthesise DNA from its own RNA, incorporating the DNA into that of its host. HIV can be passed between humans only in certain bodily fluids - blood, semen, vaginal secretions and breast milk - but once an individual is infected the virus begins to circulate through the body, coming into contact with various other cells. On the cell membrane of each HIV cell is a specific glycoprotein molecule which is specific for, and able to attach to, the cell surface marker protein found on various lymphocytes or white blood cells as they are more commonly known. Having bound to the lymphocyte, the virus employs a second receptor on the cell to facilitate its movement across the membrane and into the cell.
Once inside, HIV sheds its protective coat, resulting in the release of viral RNA and reverse transcriptase into the cytoplasm of the host cell. This reverse transcriptase synthesizes DNA from RNA and thus allows the HIV to incorporate its genetic material into that of the host, with the result that the lymphocyte begins to produce new HIV cells. There is a large amount of error in this reverse transcription, with the result that mutations in HIV are extremely common - one of the reasons that finding a vaccine has been so troublesome. These new cells leave the cell by 'budding' and travel through the blood of the host individual, repeating the cycle of infection and replication.
After a while, random mutations in the gene coding for the glycoproteins in HIV cause a change in the secondary cell-surface receptor for which it has the greatest affinity, and the HIV cells begin to preferentially attach to a different kind of lymphocyte. The HIV acts in a similar way within these cells as it did in the first type, but rather than leaving by budding, it leaves by cell lysis, rupturing and killing the cell. The lymphocytes are vital in the body's immune response and so HIV manages to simultaneously invade the body and destroy its defense against attack. This, coupled with the immune response's difficulty in identifying HIV cells as foreign makes HIV an unbeatable foe and results in what can reasonably be considered 100% death rates from AIDS in HIV positive individuals.
As the lymphocyte count drops, the sufferer becomes more and more prone to 'opportunistic infections' and steadily becomes more and more unhealthy. It is this loss of cells (and CD4+ lymphocytes in particular) that partially defines AIDS; in a HIV negative adult the CD4+ count "is usually between 600 and 1200 per cubic millimeter of blood"5. When this drops below 200 cells/ml3, the infected person can be considered to have AIDS . AIDS can also be defined by the possession of 26 (28 in children)(1) specific illnesses and cancers, with or without a CD4+ count below 200. If a person wishes to know if they are HIV positive, a test for specific antibodies is performed on their blood. These antibodies are released in response to HIV infection but are ineffective in combating it.
Another form of HIV, HIV-2, also exists but is believed to have a different origin to HIV-1 and is much rarer and less infectious. It is only found in West Africa.
There are a huge number of ideas about how HIV-AIDS arose, from P.S. Duke's (and others') claim that it is a covert alien invasion to the consensus view that it has arisen as a mutation in simian retroviruses. Although only properly documented from the 1970s onwards, there are some cases of AIDS reported from the 1950s and, using evolutionary simulations, it has been estimated that HIV is most likely to have mutated some time during the 1930s. However, because it is unclear when HIV arose, many dates for its genesis have been proposed.
In this section, the most commonly held views on how, when and where HIV/AIDS originated will be briefly explored, finishing with the most widely-accepted theory and leading into the evidence for the link between HIV and AIDS. Many of the 'theories' described below are actually more hypothesis than theory, but for consistency with their commonly used names, the use of the descriptor 'theory' is retained.
Until recently, one of the more popular of these theories has been the 'Oral Polio Vaccine' theory(1). This was proposed by Edward Hooper and is based on the fact that the polio vaccine administered widely in Western Africa in the 1950s has to be cultivated in living tissue. The theory claims that this tissue could have come from Chimpanzees infected with SIV and that this would lead to the transference of SIV to humans as HIV-1. SIV stands for Simian Immunodeficiency Virus and, as the name suggests, is similar to HIV - it is SIV that is most commonly given as the source of HIV. This theory has been refuted by the Wistar Institute in Philadelphia, which has found that the vaccine was free from both HIV and SIV and that macaque kidney cells and not Chimp cells were used to make the vaccine(1). It is also pointed out that the theory only accounts for one of the several HIV groups and that HIV was reported in humans before the polio vaccine was first used.
One of the more sensational theories about the origin of AIDS is known by the general term, 'The Conspiracy Theory'. The general theory (though there are variations) is that the US government, with the CIA, created what is known as the 'Special Cancer Virus Programme' (SCVP) during the right-wing conservative Regan presidency in a deliberate bid to exterminate large numbers of black and or homosexuals. This theory is supported by the fact that most people consider AIDS to be a disease found in homosexuals and black people. Howver, despite having originally been considered a "gay plague(8)" (AIDS was originally known as Gay Related Immune Deficiency), AIDS is actually now far more prevalent in the heterosexual community. It is, however, true that infection rates are greater in black Africans than in Caucasians, for reasons that will be discussed later. It was once believed that HIV in the USA could be traced back to the homosexually promiscuous flight attendant Gaetan Dugas, based on information gathered by Randy Shilts though this is now considered unlikely. The conspiracy theories claim that HIV has many features that suggest an artificial origin, though they do not take into account that the technology to perform such synthesis was not available when HIV first appeared.
The most widely accepted theory is the 'Hunter' theory, which simply suggests that "SIVcpz was transferred to humans as a result of chimps being killed and eaten or their blood getting into cuts or wounds on the hunter. Normally the hunter's body would have fought off SIV, but on a few occasions it adapted itself within its new human host and became HIV-1"1. The major strengths of this theory are that it explains the emergence of the many different strains of HIV, is not time-constrained and is scientifically rigorous.
There are those, such as Dr Peter Duesberg and infamously Thabo Mbeki who would contend that there is no proven link between HIV and AIDS, arguing that HIV is harmless and that it is AIDS-fighting drugs such as AZT or poverty that are the real killers. Duesberg has claimed, "AZT is a random killer of infected and non-infected cells. AZT cannot discriminate among them. It kills T-cells; B-cells; red cells, it kills all cells. AZT is chain terminator of DNA synthesis of all cells - no exceptions" . Another supporter of these claims was Dr. Robert E. Willner who famously injected himself with HIV to prove it was harmless. Unfortunately he died within the next few years of a heart attack and so no evidence could be gained from the experiment.
There is a vast amount of counter-evidence available to support the link between HIV and AIDS, with the major support outlined below. Since the late 18th century a set of four requisites for proving the pathogenicity of an organism have been used, known as Koch's postulates after the man who devised them. Koch 1 states that the germ must be found in every person with the disease(1). This is fulfilled by many research papers, such as Smith et al (1993)(9) in which 230,179 patients with AIDS-like symptoms were investigated and HIV was found in all but 174 of them. Of these, 47 had a condition known as ICL, which is essentially a T-lymphocyte count below 300 with no evidence of HIV or other cause of immunodeficiency. Thus, HIV was found in 99.9% of AIDS suffers.
Koch's second postulate is that the germ must be isolated from an individual with the disease and grown in pure culture. This was first achieved by Robert Gallo in 1984 and is now possible in almost all AIDS patients. It has also been possible to locate complete HIV genomes in the blood of AIDS patients.
Kochs 3 and 4, which respectively state that the germ must cause the disease when introduced to healthy person and must then be re-isolated from the infected person(1) have proved harder to meet, though there is evidence available. O'Neil et al (2000)(10) found that when Chimpanzees were deliberately infected with HIV-1 some began to exhibit AIDS-like symptoms. Similar results have been found in other primates. In humans, three cases of accidental infection of scientists with purified, cloned HIV have shown a link between HIV and AIDS; the same strain of HIV as had been injected was isolated from the patients at a later date(1).
Because of the ethics of deliberately infecting a human with HIV, solid laboratory evidence for the link between HIV and AIDS is difficult to come by. There are, however, a number of studies of the connection between HIV and AIDS, the only problem being that the infection has taken place in uncontrolled conditions and therefore external variables cannot be discounted. For example, in the USA and Canada, it has been found that HIV positive patients are more than 1000 times more likely to develop AIDS than those who were found to be HIV negative(1). Over a 5-year period in Uganda, those people who had contracted HIV were found to be 10 times more likely to have AIDS than those who had not(11).
Much research has been conducted in an attempt to find suitable treatments and cures for HIV-AIDS. So far up to 28million people have died from AIDS, with a further 36.1 currently living with the disease(12) - making the disease the single largest killer in the modern world. Part of the reason for the success of the virus has been the difficulty with providing a vaccine or cure, though various HIV-AIDS drugs are currently available or being researched.
Most of these fall into the category of anti-retroviral drugs, which act merely to delay the onset of AIDS and take a number of forms. There are four types of ARV currently. In order to be effective, ARVs are taken in combination, whereby 3 different drugs from at least 2 different classes are taken at once5. This method is called, unsurprisingly, combination therapy.
Because ARVs cannot prevent or cure HIV, researchers are keen to find drugs that can do so as soon as possible. As discussed before, the trouble with trying to create an HIV vaccine is that the process of copying from viral RNA to DNA is so fraught with error than mutations are rapid and common, and any vaccine that was manufactured would soon become obsolete. With this in mind, scientists have looked at less conventional methods of preventing HIV from taking hold.
Many HIV drugs have been designed to mimic a naturally occurring resistance observed in AIDS patients. Once such case is that of 5 HIV positive Australians who had all received the same infected blood transfusion, but had not developed AIDS after 14 years(4). When this was investigated, it was found that the HIV from the original blood sample had a defective gene, named nef or negative factor, which meant that the HIV was unable to properly reproduce. This is a new discovery, and as such the development of a drug to combat the nef protein is only in its infancy.
Another study that it is hoped might provide clues about an 'AIDS vaccine' is that on a group of 43 Kenyan prostitutes who remained HIV negative despite continued exposure to the disease(13). It was deduced that their immunity was due to a higher than usual number of cytoxic T-lymphocytes (CTLs) which destroy the HIV. Unfortunately, once the women stopped having regular exposure to HIV they soon became infected, the suggestion being that continued exposure is required to maintain immunity - something that is currently being investigated by Sarah Rowland-Jones and her team at Oxford University.
It has been shown by numerous studies that male circumcision reduces the likelihood of HIV infection by up to 8 times, since the foreskin contains cells that possess a receptor that is particularly receptive to HIV1(4). How this knowledge should be used is, however, contentious - with some arguing that at-risk men should be encouraged to be circumcised and others pointing out that this might encourage uneducated men in the developing world to believe that they were immune to HIV.
Research is also being done into the discovery that "a 32-base-pair deletion in the gene that codes for the CCR(5) receptor appears to block HIV infection"(4). When a study of 1995 people was performed, no people were found to both possess this mutation in the homozygous condition and be HIV positive. If it were possible to artificially create this deletion, then the therapy could be very effective since it has been shown that the CCR5 receptor is not necessary for normal bodily function.
With a projected 80 million HIV suffers by 2010(15) and no vaccine yet available there is little doubt that AIDS will continue to wreak havoc across the globe for years to come. From humble beginnings somewhere in darkest Africa, HIV has grown to become the deadliest killer in the world, invading and slowly killing the very cells that the body uses to defeat foreign bodies. As with anything of such global importance, debates will probably always rage about the nature and origins of the disease - the only real answers being provided by concerted and rigorous scientific research and application.
1 www.avert.org/evidence, 2005
2 Oxford Dictionary of English, 2003
3 After CDC(2005) http://upload.wikimedia.org/wikipedia/en/a/ae/R402a1t1.gif
4 www.sfaf.org/aids101/transmission.html#infectious_body_fluid
5 The Biology of AIDS news.bbc.co.uk/ 1/shared/spl/hi/africa/03/ biology_of_aids/html/default.stm
6 Glossary for Patients http://depts.washington.edu/madclin/patients/glossary.html
7 The AIDS-ET connection http://www.rense.com/ufo4/aidset.htm
8 http://en.wikipedia.org/wiki/Aids#Origin
9 http://www.sumeria.net/aids/willner.html
10 Smith et al, NEJM 328(6), February 1993
11 O'Neil, S.P. et al (2000) 'Progressive Infection in a Subset of HIV-1-Positive Chimpanzees' The Journal of Infectious Diseases
12 Nunn, A.J. et al (1997) 'Mortality associated with HIV-1 infection over five years in a rural Ugandan population: cohort study' BMJ
13 http://www.whitehouse.gov/onap/facts.html
14 http://news.bbc.co.uk/1/hi/health/619316.stm
15 Short, R.V. and Szabo, R. (2000) 'How does male circumcision protect against HIV infection?' BMJ 320 pp1592-1594
16 http://archives.cnn.com/2002/HEALTH/conditions/09/30/hiv.epidemic/
User Reviews
Submitted by rad1101 (user info) at 2006-01-03 07:32:26 EST (#)
Ranking: 2
actually been worried about my odds.
I'll make sure I stay away from transfusions and stick to insertive vaginal intercourse.
Submitted by Fartman (user info) at 2006-01-02 21:46:16 EST (#)
Ranking: -1
Thank you, Dr. Steiner.
And for those of you who still can't sleep, our next speaker will be Pat Robertson on Intelligent Design.
Submitted by jagmcmanus (user info) at 2006-01-02 21:39:10 EST (#)
Ranking: 2
"there are some cases of AIDS reported from the 1950s and, using evolutionary simulations, it has been estimated that HIV is most likely to have mutated some time during the 1930s. However, because it is unclear when HIV arose, many dates for its genesis have been proposed."
I think I read something similar about HIV and AIDS origins in the book 'the tipping point' I found this a very interesting read...
Submitted by Bubba2341 (user info) at 2006-01-02 21:16:03 EST (#)
Ranking: 2
I got to thinking about the initial review I left you, and
I decided it was much too harsh. The form and style of your
treatise are excellent. If you presented this in one of my
classes it would receive an "A."
Submitted by Falconer (user info) at 2006-01-02 19:31:03 EST (#)
Ranking: 2
No Comment
Submitted by whiskey_jack (user info) at 2006-01-02 15:13:35 EST (#)
Ranking: 0
Who cares about AIDS. Only teh ghey menz and blacks get it.
Submitted by missflibble (user info) at 2006-01-02 14:34:15 EST (#)
Ranking: 1
Submitted by spedmonkey (user info) at 2006-01-02 13:02:50 (#)
Ranking: 1
Nice article, wrong place to post it. I'm surprised people have let you off so easy so far.
===========================================================================================
I was soooo just like thinking that ya know?!
Submitted by Chroniclysm (user info) at 2006-01-02 14:20:48 EST (#)
Ranking: 1
No Comment
Submitted by Sassmasterr (user info) at 2006-01-02 13:58:22 EST (#)
Ranking: 2
penile
that word always brings out the junior high kid in me...
he said penile hehe
Submitted by RePet (user info) at 2006-01-02 13:53:03 EST (#)
Ranking: 1
I like it. Good essay.
Submitted by bob (user info) at 2006-01-02 13:47:08 EST (#)
Ranking: 1
If you are into AIDs and AIDs research, look up the delta 32 gene.
Submitted by spedmonkey (user info) at 2006-01-02 13:02:50 EST (#)
Ranking: 1
Nice article, wrong place to post it. I'm surprised people have let you off so easy so far.
Submitted by c1ndy (user info) at 2006-01-02 12:53:26 EST (#)
Ranking: 2
Very interesting
Submitted by TheSunGod (user info) at 2006-01-02 12:36:41 EST (#)
Ranking: 1
haha! funniest thing i've seen all day!
Submitted by Zol (user info) at 2006-01-02 10:47:11 EST (#)
Ranking: 2
Good work!
Submitted by DCWoody (user info) at 2006-01-02 10:25:49 EST (#)
Ranking: 1
I was very pissed when I found that you could get AIDS from a BJ, but 1 on 20,000 sounds like good odds to me.
Submitted by Azk (user info) at 2006-01-02 10:12:27 EST (#)
Ranking: 0
I echo the sentiments of Mr Sparkle.
Submitted by MrSparkle847 (user info) at 2006-01-02 09:52:03 EST (#)
Ranking: 2
Personally, I think that it arose from simian viruses of the same nature. In some parts of Africa, bushmeat (meat from animals hunted in the forest, usually monkeys) is eaten very frequently. I find it very conceivable that a monkey infected with a mutated HIV-like virus was slaughtered and butchered by a person with a tiny cut on his/her hand, and since no one wears gloves, hand contact with the blood could provide entry for the virus.
Given the terminology you use, it reads a little like you cited what the virus does rather than understand it yourself and paraphrase, but I always did like these disease articles, and you can never read enough on the origin of HIV. That aside, though, you should avoid posting essays like this, as people will almost certainly find them a little dry.
Submitted by Bubba2341 (user info) at 2006-01-02 08:27:04 EST (#)
Ranking: -2
Thank you, Dr. Dickweed, for telling me what I couldn't
find on Google.
1. AIDS = Anally Inserted Death Sentence.
2. AIDS = Another Infected Dick Sucker.
3. Now go die.