WASHINGTON (Reuters) -
A battle won by human ancestors against a virus that infected chimpanzees and
other primates millions of years ago may have left people today more vulnerable
to the AIDS virus, scientists said on Thursday.News (Updated June 24, 2007)
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Thu Jun 21, 2007 3:24 PM ET
By Will Dunham
WASHINGTON (Reuters) -
A battle won by human ancestors against a virus that infected chimpanzees and
other primates millions of years ago may have left people today more vulnerable
to the AIDS virus, scientists said on Thursday.
That ancient battle helped humans evolve and rely on a gene that may not protect so well against a modern retrovirus, the human immunodeficiency virus or HIV, the researchers said.
They focused on an ancient virus, known as Pan troglodytes endogenous retrovirus, or PtERV1, to find clues as to why HIV has exacted such a high toll on humanity.
"Events that happened millions of years ago have shaped human evolution, in particular susceptibility to modern human infectious diseases," Michael Emerman of the Fred Hutchinson Cancer Research Center in Seattle, Washington, who led the study, said in a telephone interview.
There is genetic evidence that the PtERV1 virus infected chimpanzees, gorillas and old-world monkeys about 4 million years ago, but no evidence it infected humans. The virus is believed to have gone extinct perhaps 2 million years ago.
Emerman's team was able to resurrect a small portion of the PtERV1 by using DNA remnants of the virus lodged in the genome of chimpanzees.
Working with cells in a laboratory, they found that an old virus-fighting gene present in people, known as TRIM5a, succeeded in neutralizing PtERV1.
The gene makes a protein that binds to and destroys the virus before it can replicate within the body, they report in the journal Science.
"However, while TRIM5a may have served humans well millions of years ago, the antiviral protein does not seem to be good at defending against any of the retroviruses that currently infect humans, such as HIV-1," Emerman said in a statement.
VIRAL INFILTRATION
Small mutations may account for this. TRIM5a taken from baboons and African green monkeys carried mutations that helped it reduce HIV in lab dishes but it was almost useless against PtERV1.
When TRIM5a worked well against PtERV1, as in humans, it was ineffective against HIV.
"In the end, this drove human evolution to be more susceptible to HIV," Emerman said.
Retroviruses have been infiltrating the genomes of human ancestors and other animals for millions of years. These viruses go into the chromosomes and DNA of the cells they infect and can get passed on from generation to generation.
In fact, such vestiges of primitive infections comprise 8 percent of the human genome, Emerman said.
Other researchers found remnants of the PtERV1 retrovirus in the genomes of chimpanzees, gorillas and some other primates in Africa, but not humans or another great ape, the orangutan.
When the chimpanzee genome was mapped, a major difference compared to the human genome was the presence of about 130 copies of PtERV1 in chimpanzees and zero in people, the researchers. The retrovirus is so mutated in living chimps that it is inactivated, the researchers said.
While the study sheds light on the historical human susceptibility to pathogens, Emerman said, it does not appear to provide immediate clues as to how to beat HIV.
Officials are concerned that the current epidemic of curable TB might evolve into a drug-resistant variety immune to existing medicines.
"It would be very scary if that happened," said Dr. Ruth McNerney, an infectious diseases expert at London's School of Hygiene and Tropical Medicine. "Tuberculosis would then turn into what it was centuries ago when it was Europe's biggest killer and wiped out generations of people."
The new plan from WHO and the Stop TB Partnership outlines actions they say are needed to slow the spread of multi-drug resistant TB and extensively drug-resistant TB, or XDR-TB.
Drug-resistant TB is primarily a problem in Asia, Africa and eastern Europe, despite the recent trans-Atlantic health scare sparked by Andrew Speaker, an American with XDR-TB who flew to several countries despite being infected.
WHO estimates that $2.15 billion is needed over the next two years to help poor countries tackle issues including disease surveillance, diagnosis and treatment. So far, the health agency says it has about $640 million.
"We're extremely concerned about multi-drug resistant tuberculosis because we've already got more than 400,000 cases occurring every year," said Dr. Paul Nunn, WHO's tuberculosis, HIV and drug-resistance coordinator.
It is also much more expensive to treat resistant TB. Treating regular tuberculosis costs as little as $16 for six months per patient. But it costs up to $15,000 to treat one XDR-TB case for several years -- with no guarantee of a cure.
Though experts say WHO's strategy is a good start, they are unsure how much of a difference it will ultimately make.
"We can try to control the damage that we see today from drug-resistant TB," said Dr. Eric Goemaere, head of Medecins Sans Frontieres in South Africa. "But we are only seeing the tip of the iceberg."
Thu Jun 21, 5:58 PM ET
A computerized pill box that patients can keep at home to dole out their drugs on schedule and in the correct doses received federal approval Thursday.
The Electronic Medication Management Assistant — EMMA — is for home use but only under the supervision of a health-care provider, the Food and Drug Administration said.
The device can be programmed to dispense individual doses of up to a month's worth of 10 different drugs, according to its manufacturer, INRange Systems Inc. The Web-connected medication box allows pharmacists, doctors and nurses to tweak both the dosing schedules and dosages of drugs loaded into the device in special blister cards. The company-described "electronic nurse" alerts patients when it's time to take a drug with visual and audible alerts.
The bread box-sized device may reduce drug identification and dosing errors, the FDA said. Expected users include aging and forgetful patients, as well as those with HIV who must adhere to complex treatment regimens.
The Altoona, Pa. company said EMMA would be available in early 2008. Company officials did not immediately return a message seeking its expected cost.
Wednesday June 20, 5:57 pm ET
A Pfizer spokesman said the company is working to answer additional questions the FDA sent in an approvable letter. The questions will not require new clinical trials, the spokesman said.
The drug candidate is aimed at treating patients infected with CCR5-tropic HIV-1 who have become resistant to one or more currently available treatments.
More than 2,000 patients worldwide have received the drug candidate through clinical trials, Pfizer said.
Pfizer also said it established an expanded access program for maraviroc in 30 countries. The program is a clinical study that makes the drug candidate available to patients in countries where they have limited treatment options.
Wednesday June 20, 5:03 pm ET
A 250-milligram dose of the antiviral bevirimat doubled antiviral effect in the Phase IIb study, compared with a previous 400-milligram dose study which failed to meet its goal. At the time, the company said the problem could have been the tablet formation.
The new study results support further dose escalation, the company said. The company said it anticipates completing a study involving a 300-milligram dose during the third quarter.
Tuesday June 19, 11:31 am ET
Anthony A. Grejda, 45, of McMurray, pleaded guilty Monday in federal court to charges of health care fraud, conspiracy and illegally distributing the painkiller hydrocodone over the Internet.
Grejda's guilty plea ended a trial that began April 25 in U.S. District Court, Pittsburgh.
Grejda filed claims for HIV and AIDS drugs that were never dispensed, which cost an insurance company and Medicaid programs in Pennsylvania and Ohio between $2.5 million and $7 million, federal prosecutors said. Grejda committed the fraud through his Crafton pharmacy, known as TDI.
Grejda also filled hundreds of painkiller prescriptions each day to patients who were never seen by doctors who issued the sham prescriptions based on a brief Internet questionnaire patients completed. Grejda supplied 3.7 million pills from September 2002 to April 2007, prosecutors said.
Grejda faces up to 40 years in prison and $1.25 million in fines when he's sentenced Oct. 19.