Just three years after smallpox was eradicated, a new epidemic caught the attention of the medical community. The US Centers for Disease Control published a study of five mysterious Los Angeles deaths in June, 1981. This is recognized as the date that Acquired Immune Deficiency Syndrome (AIDS) became a known disease. 1
Human Immunodeficiency Virus (HIV), the virus that causes AIDS, has actually been a human pathogen since about 1920. The HIV virus first evolved in Central African chimpanzees. It was most likely transmitted to a small number of Africans who hunted and butchered chimps. AIDS took hold as an epidemic along the Congo River. It seems to have made its way to Europe and the Americas by the 1960s. Due to its long latency period and a relatively slow spread, it avoided widespread detection through the 1970s. 2 Some research suggests that the spread of AIDS was also ironically accelerated by the end of the smallpox era! The smallpox vaccine appears to have offered some degree of immunity to HIV. 3 HIV silently spread around the world at the very moment that smallpox was dying out and its vaccine was decreasingly necessary.
Once it was identified, AIDS caused great alarm. Fear of AIDS dampened the sexual revolution in the 1980s. It significantly curtailed promiscuity among educated heterosexuals, even though they were not the ones at high risk, and caused a strong upsurge in the sale of condoms. 4 The epidemic engendered fear with its novelty (fear of the unknown), the rapidity of its spread, and its very high initial death rate. Though the epidemic was originally seen as American, it spread quickly to all continents. The rate of HIV transmission peaked in the mid-1980s before public awareness and precautions started to slow it down.
HIV is a retrovirus, meaning that it infects its host with a nasty trick called reverse transcription. Recall that in regular transcription, DNA is used as a template to synthesize RNA, which in turn codes for proteins. A retrovirus is made of RNA. After infecting a victim, HIV reverse-transcribes itself into six genes, and then incorporates itself into the host’s own DNA! All subsequent copies of the victim’s infected cells also contain the new genes, which get transcribed into copies of the original retrovirus during normal human transcription. 5 HIV is also especially nefarious because it attacks the immune system itself. When the viral count becomes high enough, it begins to seriously compromise the immune system, the condition that is known as AIDS. In that condition, the victim is susceptible to all manner of infectious agents.
A promising new strain of AIDS medicines emerged in the mid-1990s. They are informally called drug cocktails because they combine three or more chemical lines of defense. Drug cocktails are expensive, but have been highly effective at lowering viral counts and mitigating AIDS symptoms in many HIV+ patients. They work by interfering with the virus’s ability to reproduce, thus maintaining a viral count below the threshold necessary to cause AIDS. There are at least two documented cases of patients who have been cured completely or functionally (without further need of medicine). 6 Now there is a sense that the epidemic is coming under control in the First World. It is still a bad crisis in the Third World, where drug cocktails are unaffordable and where education and women’s rights are still sorely lacking.
To date, the HIV virus has infected about 60 million people worldwide, approximately half of whom have died of AIDS. Though transmission and death rates are on the decline, it is still one of the top ten causes of death in the world. Sub-Saharan Africa is by far the most HIV-infected region once again.
The modern gay rights movement traces its origins at least to 1969. AIDS did more than anything else to consolidate sympathy for the gay cause. The epidemic “really turned things around,” said Hank Plante, one of the first openly gay reporters on TV. “It brought a lot of gay people out of the closet, but also I think that straight people gained new respect for members of the gay and lesbian community as they saw gay people stepping up and helping their friends.” 7 Before AIDS, it was not only possible, but apparently very common for gay men to keep their sexual identity private, even from their families, for their entire lives. When a young gay man contracted AIDS, his family had to confront it with him, often in a wrenchingly emotional medical battle. The disease impacted a very sizeable number of families, who had to seriously reevaluate their image of homosexuality. Rock Hudson’s coming out and death not only made international headlines due to his universal appeal, but also made a lasting impression on his friends the Reagans. The loss had a personal impact on Ronald and Nancy, and catalyzed the president’s call to action in his second term.
Since the 1990s, at least two significant trends have followed. First, open homosexuality has become increasingly common, to the point of being perfectly ordinary in urban life and the entertainment industry. Second, gay pride has evolved into a full-fledged civil rights movement. A movement is afoot to add sexual orientation as a legally “protected class” in the US, entitled to the same anti-discriminatory protection as race, gender, or religion. The US military and Boy Scouts are two institutions that have famously rescinded such discrimination voluntarily.
By far the central thrust of the civil rights movement has been the quest for gay marriage, and this is a worldwide battle. In 1989, Denmark became the first country to grant a civil union, a quasi-marriage for same-sex couples. 8 Since then, a complex variety of gay marriages and civil unions have been legalized in several jurisdictions around the world. After Northern Europe, South America has surprisingly emerged as one of the most progressive regions. Where civil union or same-sex marriage is legal, it generally provides same-sex couples with the same rights as traditional couples, such as inheritance rights, medical benefits, and tax breaks.
There has been considerable conservative pushback. Public attitudes toward gay rights are generationally and regionally split. With an obvious reproductive handicap, homosexuality had no chance of evolving as a mainstream lifestyle. Objectively speaking, though, about 2 – 5% of human beings are homosexual, 9 and there is no compelling reason to disallow them from embracing their nature and marrying each other.
The outbreak of the HIV virus just happened to coincide with the development of genomic science and genetic engineering, biological breakthroughs that allow researchers to understand genetic material and even to modify it. When smallpox was wiped out in the 1970s, it was accomplished with a vaccine, a solution full of dead viruses that allowed the body to develop immunity to the real thing. On a scientific level, a vaccine may as well have been magic. Vaccines have been known to medicine for centuries, without any deep understanding of how they work. AIDS, on the other hand, has been combatted with thorough molecular knowledge of what HIV is and how it functions. In fact, modern genetic medicine owes a great deal to HIV / AIDS research.
The chemistry of genes has been understood only since the 1950s. By the 1980s, scientists were able to actually “read” or sequence portions of DNA. A sequence of DNA is simply a long chain of letters such as ACG-TTA-GTC-AAC etc. that spells out its nucleic acids in order from one end to the other. Genome sequencing started modestly, with viruses and bacteria. It progressed rapidly to plants and animals. The most ambitious project of all, the human genome project, took only one decade, the 1990s. The human genome project showed that there are roughly three billion base pairs in our 23 chromosomes. This genetic information includes about 20,000 genes. Identifying the location and function of thousands of genes has revolutionized medicine. Many human traits and disorders have been traced to particular genes. It is now possible to take genetic tests to identify susceptibility to many cancers and diseases. Only a small percent of the three billion base pairs are coding DNA, used to synthesize the proteins that define the genes’ functions. Many non-coding base pairs, once considered “junk DNA,” are now understood to play vital roles in regulating gene behavior. A fair percentage of DNA has no known role and probably no function at all. 10 That is to be expected. Characteristics that are health-neutral have no evolutionary pressure to disappear.
Across the human genome, most of the genetic code is universal, while somewhere around 1% is unique to each person. The identification and analysis of this 1% variation is known as DNA fingerprinting. This has become another powerful technique, with applications in criminal and disaster investigations and paternity tests. As with many contemporary issues, the ability to genetically identify individuals with a high degree of reliability has double-edged implications for security and privacy.
By comparing the genetic similarities and differences between two individuals, it is possible to ascertain when they last shared a common ancestor. Biologists make such calculations with a molecular clock, based on known rates of gene mutation. The molecular clock can even be applied to individuals from different species. The more recently they speciated from a common ancestor, the more similar their genomes are. This kind of analysis can provide very reliable information about evolutionary pre-history. It confirms, for example, consistently with fossil evidence, that humans and chimpanzees speciated about 4 million years ago. 11
Once the code of life can be read, it can also be rewritten. Genetic engineering began with the creation of recombinant DNA in the 1970s. This technique inserts one or two genes into a pre-existing, living strand of DNA. Such “gene splicing” experiments demonstrate very convincingly how inter-related all life on Earth really is. DNA can be combined from sources as disparate as humans and yeast. They fit together as if they were long lost soul mates. Though the public imagination is gripped by science-fiction fantasies of half-goat / half-men, in practice genetic chimera are less exotic. Practical examples include pest-resistant plants and bacteria that can produce human insulin. A promising but nascent application is gene therapy. In this technique, a healthy gene is patched into the DNA of someone with a genetic defect. Gene therapy is very difficult, but has already had success treating human blindness, 12 hemophilia, 13 leukemia, 14 and even the effects of aging (in mice). 15 Gene therapy has shown some promise in helping the immune system fight off HIV infection. 16 Now here’s the strangest irony of all. Gene therapy requires the use of a vector, a small piece of genetic material, to carry the healthy gene into the host cells. The vector is often a virus. Since the HIV retrovirus is especially adept at infecting cells and grafting a copy of itself into DNA, it is actually a prime candidate for this purpose. Indeed, a modified form of HIV has been used successfully as a vector for gene therapy to cure a fatal brain disease! 17 Yes, humans are finally exploiting a virus to serve our own purposes – turnabout is fair play.
The 21st century is on track to be remembered as the century of genetic engineering. The potential is staggering, as we await breakthroughs in cures for cancer, detection and treatment of more genetic diseases, the cloning of healthy tissue, and even synthetic meat. In fact, technology outpaces regulation. Unanticipated consequences could be a long time coming.
- Pepin, Jacque, The Origins of AIDS, Cambridge Press, 2011, p. 1 ↩
- This paragraph based on Pepin, Jacques, The Origins of AIDS, Cambridge University Press, 2011. ↩
- http://www.biomedcentral.com/1471-2172/11/23/abstract ↩
- Nordheimer, Jon, “With AIDS about, heterosexuals are rethinking casual sex,” New York Times, 3/22/1986, http://www.nytimes.com/1986/03/22/us/with-aids-about-heterosexuals-are-rethinking-casual-sex.html?pagewanted=all, accessed 6/08/2013. ↩
- Shors, Teri (2008). Understanding Viruses. Jones and Bartlett Publishers. ISBN 0-7637-2932-9 , pp. 48 – 50 ↩
- http://www.pri.org/stories/health/baby-born-with-aids-virus-cured-through-aggressive-treatment-13144.html ↩
- Plante, Hank, interview 2/09/13, http://www.npr.org/templates/transcript/transcript.php?storyId=171585896 , accessed 6/14/13. ↩
- http://www.qrd.org/qrd/world/europe/denmark/registered.partnership.act.with.amendments ↩
- Robison, Jennifer, “What Percentage of the Population is Gay?” Gallup, 10/08/02, http://www.gallup.com/poll/6961/what-percentage-population-gay.aspx , accessed 7/28/13. ↩
- Timmer J (2012-09-10). “Most of what you read was wrong: how press releases rewrote scientific history”. Staff / From the Minds of Ars. Ars Technica. Retrieved 2012-09-10. ↩
- http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.0030007 ↩
- http://singularityhub.com/2012/02/16/gene-therapy-for-blind-again-a-success-more-patients-to-be-treated/ ↩
- http://blogs.nature.com/news/2011/12/gene_therapy_success_for_haemo.html ↩
- http://www.cbc.ca/news/health/story/2011/08/10/leukemia-gene-therapy.html ↩
- http://www.sciencedaily.com/releases/2012/05/120514204050.htm ↩
- http://articles.philly.com/2012-05-10/news/31642321_1_gene-therapy-bubble-boy-disease-therapeutic-gene ↩
- Kaiser, Jocelyn (5 November 2009). “Gene Therapy Halts Brain Disease in Two Boys – ScienceNOW”. Sciencenow.sciencemag.org. Retrieved 17 August 2010. ↩
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