VIRUSMYTH HOMEPAGE

MONKEY BUSINESS OVER HIV'S ORIGINS

By Colman Jones

Now Feb. 1999

The much-publicised announcement at the 6th annual Conference on Retroviruses and Opportunistic Infections in Chicago in February by a team of HIV researchers - who claim to have traced the roots of the virus to a subspecies of chimpanzee in Africa - reveals more about the sorry state of 'press-release' AIDS journalism than it does about the mysteries of the disease. For all the media hoopla surrounding the new chimp find, none of the wire service stories, newspaper features, or broadcast reports sought out contrasting scientific points of view about the new findings.

The resultant media consensus hides a considerable diversity of scientific opinion about where HIV comes from - including ideas that throw a wrench into the tidy little picture AIDS researchers have painted to explain the sudden appearance of this much-feared virus around the world. In fact, more than one senior AIDS researcher interviewed about the finding suggests it's equally plausible that humans gave the virus to chimps long ago - not the other way around.
To Charles Geshekter, PhD, Professor of History at California State University in Chico, the latest finding is old news. "It's extremely unimpressive," says Geshekter, who specialises in African studies. He claims the underlying assumptions perpetuate long-standing stereotypes about chimpanzees, African sexuality and the rain forest: "it's astonishing, really."
Scientifically speaking, the way the Hahn paper drowned out a large body of other evidence suggesting HIV has been among humans for centuries attests to the power of a well-timed media blitz in navigating public opinion towards a favoured view.

The question comes down to is this: was there really a viral "Big Bang" after World War II, when the major subtypes of HIV now found around the world burst forth from a common ancestor? Or have those types existed in human populations for millenia?

These are the thorny issues facing geneticists who use DNA sequencing for understanding how HIV got to where it is today. By tracking the subtle differences between different strains of the virus, scientists believe they can estimate how far and for how long they have evolved away from a common ancestor virus after it jumped from its original animal host into humans.

Unfortunately, genetic sequencing techniques have yeilded wildly varying estimates of HIV's age. Much of this guesswork hinges on which particular protein on the virus's surface a given team decides to focus on, and how quickly they assume HIV's genetic clock is ticking. One Japanese researcher has estimated that HIV strains started evolving from a common ancestor nearly 300 years ago, whereas as the late Jonas Salk ventured the break took place about 900 years ago.
Subsequent evidence showed that some strains of HIV were actually evolving towards each other, strongly suggested that HIV is an old virus in humans. Now that different strains of HIV are recombining with each other, the question remains as to how those strains could have evolved separately in the first place.

To some, the answer is that HIV started spreading the globe long before the modern era of jet travel, when the peoples of the world lived in relative isolation. This would have allowed regional strains of HIV to evolve into the major subtypes that were found when the epidemic first came to public attention.

In many ways, it's a scenario comparable to the biological and social evolution of human populations on different continents, cut off from each other, allowing for a diversity of physically and culturally distinct races and groups. The Nature paper aims to scotch this slow evolutionary scenario, however, by attempting to prove that every single HIV particle in the world today stemmed from a small population of chimpanzees in West Africa.

By analysing a stored blood sample from one such chimpanzee who died in 1985 while in captivity, Hahn and her team reportedly found a virus more closely related to HIV in humans than any other monkey virus isolated so far. It's widely thought the comparisons provide the strongest evidence yet linking a specific species of chimpanzee to the original source of HIV.

However, despite the uniform consensus painted by media accounts, one doesn't have to go far to find scientists willing to punch holes in this latest "breakthrough", including Nobel laureate Manfred Eigen, who developed novel methods to analyse HIV sequences back in the 1980s. Eigen has long believed that human populations have harboured the virus for centuries. Speaking from the Max Planck Institute for Biophysical Chemistry in Gottingen, Germany, the veteran scientist insists "we have determined the splitting of HIV-1 and HIV-2 (the two main strains of the virus found in humans) happened many hundred, even a thousand years ago."

Andrew J. Leigh Brown, Professor of Evolutionary Genetics at the University of Edinburgh's Centre for HIV Research, thinks this new research has made a significant advance in our understanding of the origins of HIV, but adds "these authors have not shown how many chimps are infected in the wild. That has always been recognised as the critical issue in identifying the chimp as the source. They suggest this has been underestimated (and there are several reasons why that should be the case), but they don't provide direct evidence of a high prevalence [of HIV-like viruses in chimpanzees]."
Molecular biologist Paul Ewald, who teaches at Amherst College in Massachusetts, agrees the new discovery lends credence to a monkey/human crossover, but is puzzled by how hard it is to find a virus in chimps similar to that found in people. "We should see a higher frequency infection in chimps," he insists.

Ewald stresses that the issue of whether HIV jumped from primates to people or not is separate from how long the virus has been in humans. "It's really difficult to get at those issues," he remarks, "because you don't know exactly when transmission events occurred. The data that are available indicate that at least two transmission events occurred between humans and chimps, and it's not clear which direction they went."

"The assumption has always been that animals gave it to us", notes Harold P. Katner, MD, Professor of Internal Medicine and Chief of Infectious Diseases at Mercer University, in Macon, Georgia. "We may have given it to the animals", he even suggests - "maybe the disease isn't going from chimpanzees to humans, but the other way around."
Paul Ewald suggests there's an equally plausible alternative explanation that's consistent with the data, namely a viral migration from chimps into humans, and then back from humans to chimps.

"If you look at another retrovirus - HTLV - there is evidence that it has gone from humans into primates, so if it can do it, maybe HIV can do it," Ewald suggests. For him, more samples are needed in order to definitively determine the direction of spread.

But such alternative speculations are of little interest to more establishment researchers like John Coffin, Professor of Molecular Biology and Microbiology at Boston's Tufts University. Coffin says, that as far as he's concerned, the latest data confirm his belief in a one way chimp-to-human passage.

"Clearly the data point very strongly in that direction, and make it very unlikely that there is anything else going on," Coffin suggests, although he agrees HIV has "probably been coming into the human population for a very long time", noting, "there is nothing different about what people were doing in the 1950s to get infected than they would have been doing tens of thousands of years before."

George Pankey, Director of Infectious Disease Research at the Alton Ochsner Medical Foundation in New Orleans, agrees "the contacts between the natives and monkeys, whether actually eating them or handling them and being scratched by them, has been going on much longer than this particular outbreak."

It's important to figure out what is meant by the term "the ancestral host", adds John MacDonald, who heads the Department of Genetics at the University of Georgia in Athens. Even if this particular species of chimp can be found to harbour the same virus found in people, MacDonald points out, it does not mean that the virus necessarily originated in chimps.

Indeed, chimps may have been an intermediate host, having themselves been infected from some other source. Viruses like HIV, MacDonald says, may have travelled through many species before finally infecting humans.

Katner and Pankey, both skeptics of the African origin of HIV, have published reviews suggesting HIV likely originated in Northern Europe, not Africa, from slow-growing viruses in sheep. "If you have a disease in a newly-exposed population," Katner notes, "it tends to be a lot more aggressive: measles in Hawaii knocked off almost all the Hawaiians, for example, because they had no resistance. So if AIDS really came out of Africa, we should have seen resistance genes not in whites, but in Africans - but it's the opposite: the highly prevalence of [HIV resistance] genes is in Northern Europe, extending all the way over to northern India. That refutes the African hypothesis."

"I'm still not totally convinced that we know when this started and how long it's been around", Pankey adds. "To say you have the exact same virus in four monkeys - that's not enough for me. It's undeniable that these particular animals have this strain, but does this apply to other strains?"

A good example is the feline immunodeficiency virus (FIV), which causes an AIDS-like syndrome in cats. Pankey notes Hahn's finding doesn't explain where cats got their virus, and why it causes disease in them, but not in humans - the reverse of the chimp situation.

MacDonald, who also serves on the editorial board of the journal Genetica, cautions, "we have much to learn about the processes underlying retrovirus evolution before we can conclude that we truly understand the origins of HIV" .

Compounding the uncertainty is that most laypeople, journalists - and even a good number of scientists - don't have the expertise to wade through the kind of jargon found in these types of papers. Ewald notes, "there has been a tendency sometimes to let ideas become established without challenge, just because some of the arguments don't have many experts in the relevant areas."

To some the latest data, far from shedding light on the mysteries of AIDS, only further serves to cast doubts on the increasingly shaky edifice that HIV-based science has come to represent. For skeptics, one of the most convincing arguments against HIV as the cause of AIDS was its failure to cause the syndrome in our closest genetic relative, an anomaly noted by Hahn and her team. If these chimpanzees - whose DNA is 98.5% identical to that of humans - were ancient carriers of HIV, why did they never develop AIDS?

HIV researchers don't have a definite answer to that question, but hope that 1.5% of genetic dissimilarity will eventually reveal why people with HIV get AIDS while chimps don't. But the notion that this latest finding will yield fresh new insights for a successful vaccine is quashed by researchers on both ends of the age debate. For example, Tuft University's John Coffin, when pressed on the supposed scientific boon this new finding reportedly provides researchers, agrees: "I don't think this finding adds to much to what we already believed and knew to be true when you put known HIV strains into chimpanzees" - a sentiment seconded by Ewald.

And the new information isn't likely to be greeted with open arms by African countries, which aren't exactly eager to be tagged as the home to a plague the WHO claims has now spread to 34 million people world-wide, the vast majority of them in sub-Saharan Africa.

Katner also warns of the xenophobic and ethno-centric attitudes that plague much of the research in this area. Science, he notes, tries to be objective but can't help but be coloured by its cultural eyes.

"We always blame diseases on other cultures", he remarks. "Syphilis was thought a French disease in England, and vice versa - and this ethnocentrism is something that is very difficult for us to escape from. The same things happens with anthropo-centrism: did this virus really evolve in animals and hit us, or was it vice versa?"

Geshekter, who has taken 12 research trips to Africa, recently presenting a paper for the General Assembly of the Council for the Development of Social Science Research in Dakar, entitled "A Critical Reappraisal of African AIDS Research and Western Sexual Stereotypes" says the latest research "absolutely confirms, with more even outrageous examples, the very kinds of things that I've been criticizing for years about so-called 'AIDS research' in Africa."

"There are two sets of issues that really get run together and need to be carefully cracked apart", he notes. "The question of whether or not a chain of viral particles exists in the first place is one issue. The other issue, which is where the prejudice and racial stereotypes come in, is over the entire definition of a so-called 'case of AIDS' in Africa: what are we counting in Africa when we talk about AIDS cases? You're faced with a definition of a syndrome which differs decisively in Africa from what it is we're said to be counting in Canada, the US, or Western Europe."

Geshekter isn't surprised to see a flood of media hype about AIDS in Africa, especially since the next international AIDS conference takes place in Durban, SA, in the year 2000. "Much of this research is designed to stoke the fires, keep the interest up, and generate concern over the next AIDS conference in South Africa - that's the context in which this is occurring."

But he's shocked by how quick reporters are to toe the official line. "At these kinds of press conferences about the latest discoveries on HIV or AIDS, unfortunately, most journalists don't ask those critical questions to begin with. The dissent among scientists is out there, however there is this blanket of consensus among the media that I am at a loss to explain."

To Geshekter, the hype surrounding the chimp finding involves larger questions about the sociology of knowledge and media complicity. "The problem is that there is a bandwagon mentality which has taken hold, and dissidents - at any level you want to talk about, whether in microbiology or at a social science level like myself - are going to be branded as heretics. I contend that we dissidents are the ones in the conservative tradition of public checking, which is what science is really all about."

Colman Jones is an award-winning journalist living in Toronto and a member of the CSWA.

VIRUSMYTH HOMEPAGE