AIDS virus weakness detected

Thu Feb 15, 2007 3:45 AM GMT

By Will Dunham

WASHINGTON (Reuters) - Scientists have captured an image of the AIDS virus in a biological handshake with the immune cells it attacks, and said on Wednesday they hope this can help lead to a better vaccine against the incurable disease.

They pinpointed a place on the outside of the human immunodeficiency virus that could be vulnerable to antibodies that could block it from infecting human cells.

U.S. National Institutes of Health researcher Peter Kwong said the study, published in the journal Nature, may reveal HIV's long-sought "site of vulnerability" that can be targeted with a vaccine aimed at preventing initial infection.

"Having that site and knowing that you can make antibodies against it means that a vaccine is possible," Kwong said in a telephone interview.

"It doesn't say we've gotten there. But it's taken it off the list from an impossible dream and converted it to something that is a (mere) technical barrier."

Experts agree that a vaccine is the only hope of stopping the pandemic of AIDS, which has killed more than 25 million people since it was first recognized in 1981. About 40 million people now live with HIV, with sub-Saharan Africa hardest hit.

But while dozens of potential vaccines are in development, only two AIDS vaccine candidates are in advanced human trials -- one made by Merck and Co. and another by Sanofi-Aventis SA.

Because the virus attacks immune system cells, it has been especially difficult to design a vaccine to fight it.

The team at the National Institute of Allergy and Infectious Diseases, part of the NIH, made atomic-level images of the virus.

They revealed the structure of a protein on the surface of HIV as it looks while the protein is bound to an infection-fighting antibody. They said this protein, called gp120, seems susceptible to attack by this antibody, which is called b12 and is capable of broadly neutralizing the virus.

An antibody is an immune system protein that helps seek and destroy invaders like viruses and bacteria.

CAUTIOUS HANDSHAKE

The researchers detailed the precise interaction as the virus tries to grab and infect cells sent to protect the body.

"The first contact is like a cautious handshake, which then becomes a hearty bear hug," said Dr. Gary Nabel, an NIH vaccine expert and a co-author of the research.

The virus uses the protein gp120 to gain entry into the CD4 T-cells it infects. But the researchers also found that the antibody b12 can block this process.

The virus mutates quickly and continuously to beat the immune system's efforts to target it. It also is cloaked in such a way that it stops antibodies from blocking the proteins that HIV uses to bind to a cell and infect it.

So this is a critical area of vulnerability, Nabel said. "This is certainly one of the best leads to come along in recent years," he said.

NIAID Director Dr. Anthony Fauci said the findings are of great importance, but much more work in animal and human studies is needed, and any vaccine is years away.

"I don't think there's any one particular thing that, in and of itself, is the show-stopper. But I don't think we could really make substantial, fundamentally scientifically based progress until we got this very important information," he said.

Lengthy Battle Seen Remaining Vs. AIDS

Sunday February 18, 7:36 AM

It may be possible to battle AIDS into a low-rate of infection, but it will take a long time and elimination of the disease seems unlikely, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Disease said Saturday.

It's a disease transmitted by sexual activity, which is a fundamental component of human behavior, "so it isn't going to be easy to shut it off," Fauci said at the annual meeting of the American Association for the Advancement of Science.

A quarter-century after doctors first began recording cases of the illness, AIDS gets fewer headlines now that drugs are available to keep it in check in infected people, but the drugs don't eliminate the virus.

Currently there are 40,000 new infections in the United States each year with HIV _ the virus that causes AIDS _ and 4.3 million new infections around the world, he said.

Fauci, a longtime AIDS researcher and the government's point man on the disease, estimated that one in four Americans with HIV don't know they are infected.

Public fatigue in reading and hearing about AIDS can become a problem, he added, because "once you take it off the radar screen it's hard to get out the message of prevention."

It's important for infected people to get diagnosed and treated, he said, because people who know they have the disease are less likely to spread it to others. And while current triple-drug treatment can't eliminate the disease, it can reduce the amount of virus in the system sharply, also helping prevent spread.

Modern three-drug treatment is now being used in parts of Africa and infected people there are using the drugs as prescribed, Fauci said. Starting the treatment in Africa with the triple-drug dose reduces the speed with which the disease can build resistance, he said, rather than starting with a single- or two-drug regimen.

But, Fauci said, resistance to drugs develops sooner or later.

There are several new drugs in the pipeline, many of them promising, for use as second treatments in patients whose disease develops resistance to current therapy. Among the approaches, he said, are drugs to block fusion of the virus with human immune cells and others that may prevent the virus from maturing, he said.

Merck cuts price on AIDS drug Efavirenz

Thu Feb 15, 2007 7:20 AM ET

BANGKOK (Reuters) - Pharmaceutical giant Merck & Co. announced on Thursday a reduction in the price of its HIV-AIDS drug, Efavirenz, for poor countries and those hit hard by the disease, including Thailand.

Thailand, which shocked the drug maker in November when it announced plans to break Merck's patent in order to buy or make generic copies of Efavirenz, would see its price drop to 700 baht per patient per month, the company said in a statement.

Merck had previously sold Efavirenz at a non-profit price of 1,300 baht per treatment per month in Thailand.

"Merck is lowering the price of the 600 mg formulation of Efavirenz due to efficiencies resulting from improved manufacturing processes," the company said.

A spokesman for Merck's Thai subsidiary also attributed the lower Thai price to a more favorable exchange rate.

Last month, the Health Ministry issued compulsory licenses for the heart disease drug Plavix, made by Bristol-Myers Squibb and Sanofi-Aventis and Abbott Laboratories' Kaletra to treat HIV/AIDS after a similar move on another AIDS drug last year.

The licenses, which Thai health officials said would save the country up to 800 million baht ($24 million) a year, drew praise from AIDS activists but flak from Washington and the drug industry, which are urging the ministry to rescind them.

Merck said it was the second time it had cut the price for a 600 mg formulation of Efavirenz in less than a year.

Least developed countries or middle-income nations with adult HIV prevalence rates of one percent or more will get a 14.5 percent reduction to $0.65 per day, or $237.25 per patient per month.

The price will drop 5.8 percent to $1.80 per day, or $657 per patient per year, for middle-income countries with an adult HIV rate of less than one percent.

Pfizer's AIDS drug to get faster review

Tue Feb 13, 2007 2:30 PM GMT

NEW YORK (Reuters) - Pfizer Inc. <PFE.N> said on Tuesday its HIV treatment maraviroc will receive an accelerated review from regulators in the United States and Europe.

If approved by the regulatory agencies, maraviroc would be the first in a new class of HIV/AIDS treatments called CCR5 antagonists that work by blocking viral entry, the drug maker said.

Most existing HIV drugs work inside the body's immune cells, after the virus has infected a patient.

Rather than fighting HIV inside white blood cells, CCR5 antagonists prevent the virus produced by infected cells from entering uninfected cells by blocking its predominant entry route, the CCR5 co-receptor.

The U.S. Food and Drug Administration grants accelerated reviews to potential medicines that could represent a major improvement over current treatments. The expedited process means the agency will decide whether to approve the drug within six months, rather than the more typical period of up to one year.

Study says marijuana eases HIV-related pain

Tue Feb 13, 2007 6:11 AM GMT

By Will Dunham

WASHINGTON (Reuters) - Smoking marijuana eases a type of chronic foot pain in people with the AIDS virus, according to a study published on Monday that the researchers touted as demonstrating marijuana's medicinal benefits.

But the White House drug policy office said the research was flawed and offered only "false hope."

The study, appearing in the journal Neurology, focussed on sensory neuropathy -- a kind of severe nerve pain usually felt as aching, painful numbness and burning in the feet -- associated with human immunodeficiency virus infection.

HIV-infected people who smoked marijuana reported a 34-percent reduction in daily pain from this condition, compared to a 17-percent decline among those who smoked placebos.

Fifty HIV-infected adults, mostly men, who had this pain but otherwise were in stable health took part from 2003 to 2005. All were previous marijuana smokers but not considered drug abusers. They were told to stop using it prior to the study.

Half of them smoked marijuana cigarettes three times a day for five days. The other half smoked placebo cigarettes that were identical other than having had the cannabinoids -- the primary active components of the plant -- extracted.

Half the marijuana smokers said their pain level had declined by more than 30 percent, while a quarter of the placebo group reported similar pain reduction. The volunteers had no serious side effects.

Sensory neuropathy affects about a third of HIV-infected people, making walking or standing hard.

'SMOKE SCREEN'

Lead researcher Dr. Donald Abrams, one of the first doctors to study AIDS at the start of the epidemic, said the research demonstrated in a carefully conducted clinical trial that smoking marijuana provides some benefit to these patients.

"I think that there are people out there who say there is no evidence that marijuana is medicine, that this is all just a smoke screen," Abrams, of San Francisco General Hospital and University of California San Francisco, said in an interview.

Abrams said he hoped his findings would provide evidence "to help answer this question in an intelligent fashion."

There is a fierce debate over whether marijuana, an illegal drug under U.S. federal law, should be legal for medical uses like treating pain or nausea in AIDS or cancer patients.

David Murray, the White House Office of National Drug Control Policy's chief scientist, said the suffering of AIDS patients is an issue of great concern.

"Unfortunately, this particular study is not terribly convincing," Murray said, citing what he saw as methodological problems.

"Unfortunately, it will lead many people into a false hope that street marijuana is somehow going to be the thing I can use that will make me feel better and won't jeopardise my health. Now that is a fraud and a dangerous one," he told Reuters.

The study found the relief from smoking marijuana was comparable to that provided by pills now used to treat this nerve pain. But some patients are not helped by these anti-seizure medications, and others cannot tolerate them, drawing interest in marijuana as an alternative.

Californian Diana Dodson, a 50-year-old grandmother who got AIDS via a contaminated blood product, said some pain medications leave her in a stupor.

"I just want people to understand that this is about sick people who deserve a quality of life. If it's something that can help us, we should have safe access to it," Dodson, one of the patients in the study, said of marijuana.

India to study if doctors prescribe proper HIV-AIDS drugs

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