"OMG! An HIV-like virus that is easily transmissible," was the email I recently got from a gay friend. He was forwarding a rumor about a new virus spreading like wildfire in China. Supposedly it causes AIDS-like symptoms, along with debilitating depression, but it incubates as rapidly as flu. The rumors started flying last summer; by now, news media all over the world have carried the story. Reportedly, researchers are working to see if a new pathogen - possibly a retrovirus - can be cultured from samples provided by some of these patients.
But when the BBC weighed in, it pooh-poohed the story. From Shanghai, BBC commentator Chris Hogg wrote:
Hundreds of people in China believe they might have a new disease with HIV-like symptoms, but doctors suggest their illness could be the result of a mental rather than a physical condition. ... Doctors are blaming a breakdown in trust between the medical profession and patients, who fear they are being lied to when their diagnostic tests come back negative.
Hogg went on to describe a few cases where a Chinese person came up HIV-negative on several tests, only to continue frantically reporting an array of symptoms.
This isn't the first time that the medical establishment has pooh-poohed a growing cohort of patients, telling them that the pain and agony they're experiencing is just a figment of their imagination.
The CFS Controversy
Witness the stand-offish posture that the CDC and most doctors still maintain towards chronic fatigue syndrome. For decades now, because of the deep depression that often impacts people with CFS, some authorities view CFS as a mental illness. Today the CDC still classifies CFS as a "disorder," not an infectious disease, saying, "The cause or causes of CFS remain unknown." As recently as 1993, a Lancet article characterized CFS as a psychiatric condition. Yet some observers still have the opinion that CFS will be found to have a viral cause - possibly a retrovirus.
Some doctors even pooh-pooh diseases that are proven to have a pathogenic cause, like Lyme disease - whose cause (insect bites that transmit infection by a nasty bacteria) has been scientifically proven beyond a shadow of a doubt. Yet amazingly enough, there are still doctors around the United States who won't treat Lyme disease as such because they insist that the depression that often accompanies Lyme makes it a "mental illness."
If some alert researcher does spot a new "HIV-like" virus in a Chinese lab culture, it will add another name to the growing family of known retroviruses. So it's a good moment for an overview, since the retroviruses have such an intriguing history with the human race.
A Family of Killers
Retroviruses are RNA-based, not DNA-based. "Retro" means that their reproduction MO is exactly the opposite to that of DNA viruses. When an RNA virus penetrates a host cell, it has to transcribe its RNA into DNA before it can replicate itself into millions of copies.
The many-branched RV family is currently divided into seven genuses: alpha, beta, gamma, delta, episilon, lentiviruses and spumaviruses. They all affect vertebrates (i.e. creatures with backbones), and they all cause some sort of cancer or immune-system disorder. Once these RVs have entrenched themselves in a living body, they can even become endogenous, meaning that the host's infected sperm and ova carry them into the reproductive process, so they're inherited by the host's offspring. Possible example: multiple sclerosis, which has recently been linked to retroviruses. European researchers have detected particles of the human endogenous retroviruses (HERV)-W in MS patients. So these researchers now talk about an MS-associated retrovirus (MSRV).
Retroviruses were first discovered in the early 1900s by scientists studying leukemia in chickens. But it was not till the 1960s, with growing understanding of how DNA works, that the retroviruses' up-the-down-staircase RNA mode was discovered. Clear till the 1980s, these unique viruses were thought to infect only animals. Among the known variants were equine infectious anemia virus (EIAV) and feline leukeumia virus (FeLV). In the 1970s, as both a show-horse owner and a purebred cat owner, I remember the first rush to testing when these two diseases were identified as retrovirus-caused. There was the shock of horror and despair when you learned that one of your prized animals was infected.
Still other retroviruses were found to affect cattle and mice. And, notably, there was the simian immunodeficiency virus (SIV) found in primates.
An Ancient Epidemic
Not till 1977 did researchers began fingering the first retroviruses in humans. That year, in Japan, a researcher noted a sizable cohort of Japanese adults who suffered from a lethal form of T-cell lymphoma. By 1979, U.S. scientist Robert Gallo and his associates identified the cause of this lymphoma as a human retrovirus, dubbed HTLV-1. Next came discovery of a similar virus, HTLV-2, which has since been linked to human hairy-cell leukemia.
On the heels of these revelations came the historic discovery, in 1983, of a third human retrovirus that was originally called LAV, then HTLV-3, by Luc Montagnier and his associates in France. Shortly afterward, in the United States, Gallo and his team linked this newly noted retrovirus to a mysterious and usually fatal immune-related disease that had been emerging in Africa, the Caribbean and the United States.
In due course the newcomer was renamed as the human immunodeficiency virus, or HIV, because some of its characteristics differed from those of HTLV-2 and -2. Today HIV is classified in the lentivirus ("slow virus") genus, along with FeLV and EIAV, while the two HTLVs are placed in a different branch, the delta genus.
Controversy rages over just how long the retroviruses have been making life miserable for living things with backbones. Researchers who insist that HIV emerged only recently in Africa have argued that SIV must have mutated and leaped to African humans through the eating of monkey meat. Others disagree, pointing to northern Europe's high incidence of a mutant gene called CCR5 delta 32, that confers an inherited resistance to HIV. Ten percent of northern Europeans carry this mutant gene. In the study of population genetics, it's generally agreed that a high gene frequency will only be found where a disease has been around for many centuries, prompting the appearance of a resistance mutation that has to spread slowly through a population, generation by generation, for many hundreds of years, before it attains that high frequency.
Interestingly enough, HTLV-1 has an ancient pedigree. Genetic traces of it have been found in 1500-year-old Indian mummies in Ecuador. Adding to this significance is the fact that ancient pottery found in that part of South America is similar to certain ancient Japanese pottery. So some historians suggest that there were ancient contacts between Ecuador and Japan, where HTLV-1 was first discovered in 1977.
Springboarding From Animals
Controversy also rages over how many of these animal retroviruses can be transmitted to humans.
The possibility that HIV-1 mutated into humans from primates is not the only one. In 2005, researchers in Africa's Cameroon collected blood samples from bush-meat hunters and identified two new HTLVs, dubbed -3 and - 4. As hunger hits ever harder in developing countries with their exploding populations, there is an ever more frantic rush to kill wild animals as a source of meat-market protein - including monkeys. Lead author of the study, Nathan Wolfe of the Bloomberg School of Public Health, said later, "The discoveries of HTLV-3 and HTLV-4 show that, far from being rare events, retroviruses are actively crossing into human populations."
Another possible case of animal-to-human jumping might be found in chronic fatigue syndrome. Some researchers claim that CFS is linked to a newly identified mouse virus, XMRV (xenotropic murine leukemia virus-related virus). XMRV belongs to the gamma genus and is related to longer-known mouse leukemia viruses. As I said before, many in the medical establishment still dismiss CFS as one of those "mental diseases," and nobody is sure yet how XMRVs might be transmitted.
But the CDC recently admitted, "Researchers from the Food and Drug Administration (FDA), the National Institutes of Health (NIH), and Harvard Medical School reported evidence of MLVs in about 87% of CFS patients and 7% of healthy blood donors." So XMRV's possible presence in the U.S. blood supply has become a troubling question -- one that researchers are trying to answer.
Back to the Chinese panic about that "AIDS-like disease."
As I write this column, Beijing is doing the now-familiar "imaginary disease" dance. In The Epoch Times, staffer Chen Yillian writes:
Official media have stepped in to put the matter to rest: there is no such disease, and people claiming to be sick from it need psychological help.
But the fact that Beijing previously denied the existence of SARS has only fed the fires of rumor. It will take time - and dogged ongoing work by researchers with open minds - to tell us more.
All in all, the emerging story of human relationships with the retroviruses is a complicated one, and far from perfectly understood. In his bestselling book Guns, Germs and Steel, Jared Diamond put it this way:
The major killers of humanity throughout our recent history are infectious diseases that evolved from diseases of animals. ... Because diseases have been the biggest killers of people, they have also been decisive shapers of history.
A shorter version of this piece appeared previously in my "Left Field" column in A & U Magazine. I've been reporting on AIDS politics and public-health politics in this column for 12 years.