On The Origins Of HIV (part 3 of 3)

There may be some who have recently read my blog posts and have disagreed with some of the things I stated. HIV, like many other things, is surrounded with conspiracy theories, so I will now contemplate a few of these and hope to give evidence to suggest why they deserve to be called conspiracy.

The first of these theories is one that had the most support for a certain time, the idea that HIV was produced in a lab in America and not as a product of natural evolution of SIV, following its zoonosis. This theory was touted very strongly by some individuals. The idea that HIV was man-made goes hand in hand with a further conspiracy that it was made for biological warfare against black and homosexual people. A door-to-door survey, conducted in California by Klonoff and Landrine in 1999, found that 27% of the black Americans they spoke to believed that HIV had been made in a government lab. A further study, this time a telephone survey conducted by Bogart and Thorburn, found that 20% of men and 12% of women strongly agreed with the statement “AIDS is a form of genocide against blacks.” They also found that  30% of men and 27% of women agreed with the statement “HIV was produced in a government lab.” 


It was claimed that HIV was produced under the auspices of the Special Virus (Cancer) Program, which ran in the US between 1962 and 1978, and tested on human subjects – starting the pandemic. At the time the claim was made, the dates of the evolution of SIV to HIV had not been fully elucidated and the earliest known examples of HIV were those first found in America in 1983. Since then it has been calculated that HIV is much older than that (between 1884 and 1924 as I explained in post 2) and that the first known sample of HIV was found in the Belgian Congo in 1959. I suppose we can’t rule out for certain that HIV wasn’t produced in a lab between 1962 and 1978 but this would not have been the start of the pandemic spread.

A second conspiracy to be considered centres around the production of the hepatitis B vaccine. This vaccine began pilot testing in the US in the early 70’s and was given to gay men to help stop the spread of the hepatitis B virus (HBV). In order to produce the vaccine it was necessary to grow it in chimpanzee cells. It is therefore argued that the vaccine may have become contaminated with SIV, which then entered humans through injection of the vaccine, allowing the mutation to HIV. For a time the dates seemed to fit, the vaccine began production in the early 70s and the first known case of HIV was 1983. However, as with the theory of its production in a lab, much earlier examples of HIV were later found which lay to rest the idea that the HBV vaccine was to blame for the existence of HIV.

The last theory to consider involves another vaccine, this time the oral polio vaccine (OPV). In 1955, Jonas Salk produced the inactivated polio vaccine (IPV), which quickly made a massive impact on the number of cases of polio worldwide. Later, in 1962, Albert Sabin produced OPV which, instead of a dead form of the polio virus, used a much weakened version (an attenuated form) which gave much more specific (and therefore better) immunity. In order to make the poliomyelitis virus attenuated so as not to cause symptoms it was necessary to grow it in chimpanzee cells. As had been argued with the HBV vaccine, Edward Hooper in his book The River, put forward the idea that chimp cells may have been infected with SIV, thus giving the chance for SIV to enter humans and mutate. This idea was strongly refuted and it was argued that the chimp cells could not have contained SIV because measures would have been taken to avoid such contamination. Further evidence against OPV as the cause of HIV can be found in the fact that, as the name implies, OPV is given orally and the stomach and intestines are highly adapted to prevent the entry of any infectious agent, making it highly unlikely that, had the vaccine been contaminated with SIV, it would have been able to enter the human blood stream. And finally, once again, the dates just don’t fit given the finding of a HIV positive patient from 1959.

So the origins of HIV were once shrouded in mystery and conspiracy with many people believing it to have been man-made and some going as far as believing it to be made for use as a biological weapon. However, as is often the case, the more science looked into the true origins of the virus the more the evidence piled up against these conspiracies. It is now generally accepted that HIV was formed through natural evolution following the transmission of SIV to a human host, most likely through the preparation of bush meat in West Africa sometime in the late 19^th or early 20^th century. There are those who still won’t fully accept these facts but I hope that I have managed at least to show that the science behind the origin of HIV is far more compelling than any covered up wrong-doing, deliberate creation or accidental contamination of a vaccine.

So that concludes the first of my science blog posts. I hope I have at least provided some information and education if no more than that. Stay tuned for more of my blog - I'm not sure what will be next; I’ll see what takes my fancy. 

On The Origins Of HIV (part 2 of 3)

So the question is this: what discovery was made in 1999 that painted the picture of the evolutionary origins of HIV? It all stated with a frozen sample of SIV which was found in the species Pan troglodytes troglodytes, commonly referred to as the chimpanzee. This sample of SIVcpz (with the cpz standing for chimpanzee) was discovered and analysed by Gao et al. who published their findings in the journal Nature. In their paper they listed 5 criteria which provide strong evidence of a link between SIV and HIV. These were…

1) Similarities in viral genome organisation

2) Phylogenetic relatedness (a way of looking at how closely related two things are in an evolutionary sense)

3) Prevalence in natural host

4) Geographical coincidence

5) Plausible routes of transmission

SIVcpz satisfied all of these criteria. In particular, this strain of SIVcpz showed very close genetic similarity to HIV-1 (the pandemic strain of the virus) indicating that HIV may have stemmed from SIV (it is thought to be that way round, as SIV has been known of for much longer and is now believed to be around 32,000 years old, much older than the human counterpart).

Once strong evidence of a link between HIV and SIV had been found, the next mystery to solve was why SIV mutated to produce HIV. Many theories have been proposed, the most plausible of these being known as the “hunter theory”. This theory centres on the premise that SIV was able to get into humans through the preparation of bush meat in Africa. The killing and eating of chimpanzee meat would have allowed for the blood of the chimps to come into contact with any wounds or cuts the hunters may have suffered. This mixing of blood gave the chance for SIV to enter a new human host. Once inside humans, the SIV would have come under attack from our immune system. as with any virus. This in turn would have applied selection pressure to the SIV, forcing it to evolve rapidly in order to ensure its survival. This rapid evolution eventually made the SIV perfectly adapted to survive in its new host and less well adapted to survive in its former host – thus completing the transition from SIV to HIV. And so it began…

From this humble beginning the infection of a few hunter-gatherers in Africa, HIV was able to spread worldwide and infect some 33.3 million people. However, the question still remained when did SIV jump from chimps to man and subsequently evolve to HIV, a process known as zoonosis. The earliest samples of HIV date back to just over 50 years ago. A plasma sample of HIV was found in an adult male in what is now the Democratic Republic of Congo, dating to 1959 (Zhu et al. 1998) and later, a lymph node sample was found in an adult female from the same area dating to 1960 (Worborey et al. 2008). Using these early samples Worobey et al. came up with an estimate for the zoonosis to have occurred sometime between 1884 and 1924, a date estimated by using the mutation rate between the two early samples of HIV and then comparing rate of change with the change made from the SIV genome. Think of this in terms of a car journey – if you know the distance between points A and B during a particular journey is 30 miles and you know this took an hour, you can easily work out the mph speed. If you also knew where you started your journey and how far you’ve travelled, let’s say 120 miles, you can work out that you started the journey 4 hours ago (assuming a constant speed). Using this metaphor, the genomes of the two different HIV samples can be thought of as points A and B and SIV can be thought of as the starting point.

So that concludes what is generally accepted as the origins of HIV. In my next post we will have a look at some of the conspiracy theories surrounding HIV and why they deserve the title “conspiracy” in order to round off this 3 part blog post.  

On The Origins Of HIV (part 1 of 3)

It was estimated in 2009 that a staggering 33.3 million people were infected with HIV. To put this into some context, that’s more than half the population of Britain infected with a virus that will most likely result in their death. HIV infection leads to acquired immunodeficiency syndrome (AIDS) which leaves sufferers at the mercy of a plethora of diseases which are often harmless to a healthy individual. What I’d like to look at with you for my first three posts is where HIV came from. Is it some blight set upon us by a vengeful God? Was it designed in an American research lab? Is it a biological warfare attack on blacks and homosexuals? I think it’s pretty safe for me to say no, no and no to all of those options, though there are many people who believe at least one, if not more of these. Over these 3 posts I’ll take you through the reasons why I believe I can safely say no to those options before touching on some of the conspiracy theories surrounding HIV for a little amusement.

 Firstly, a quick bit of history. HIV (of a sort) first came to the forefront of the scientific community in 1981 when four homosexual men in San Francisco were found with rare infections and a fever of “unknown origin” (Gottlieb et al. 1981). Later studies of these men found them to have highly deficient immune system consistent with an acquired immunodeficiency. The virus responsible for this condition was isolated in 1983 (Barre-Sinoussi et al. 1983) and later termed the human immunodeficiency virus (HIV). As more and more people were diagnosed with HIV, minds began to turn to the origins of the virus.

It had been known for some time that monkeys were susceptible to a similar disease, caused by a slightly different virus known as simian immunodeficiency virus (SIV). Genetic analysis of different SIV strains showed striking similarities between the two viruses which were far too powerful to be down to chance alone. This led the scientific community to believe there must be an evolutionary link between HIV and SIV. While the link between SIV and HIV was hypothesised it wasn’t until 1999 that credible evidence was found.

Stay tuned to find out what changed in 1999…

To Christen the blog

So a brief introduction before getting into the science. I'm currently a student at UCL on my summer break and wanting to share some of the fantastic world of science with you. On this blog I will share with you random bits of this world that I find interesting enough to write about and share with you. Chances are there will be a large focus on HIV as this is an area of real interest to me, but other things like circadian rhythms, infectious diseases, the immune system and so on may well come up. Some science based sport topics may also come up depending what floats my boat (if I get cramp playing football chances are I'll write an article on cramp).


Feel free to keep checking back in to see the things that are amusing my mind each week and hopefully to learn a thing or two (or at least kill a few minutes while the kettle boils).


First post will follow soon, to be titled "on the origin of HIV."


Take it easy!