HIV infection stems from few viruses

The finding provides important clues in the ongoing search for an effective HIV/AIDS vaccine, said researchers at the University of Alabama at Birmingham (UAB). The UAB team found that among billions of HIV variants only a few lead to sexual transmission.

Earlier studies have shown that a ‘bottleneck’ effect occurs where few versions of the virus lead to infection while many variants are present in the blood. The UAB study is the first to use genetic analysis and mathematical modeling to identify precisely those viruses responsible for HIV transmission.

George M. Shaw, M.D., Ph.D., professor in the UAB departments of Medicine and Microbiology and senior author on the report, said the research sheds new light on potential vulnerabilities in the virus at a time when science, medicine and society are still reeling from the failure of a major HIV vaccine clinical trial.

“We can now identify unambiguously those viruses that are responsible for sexual transmission of HIV-1. For the first time we can see clearly the face of the enemy,” said Shaw, a project leader with the Center for HIV/AIDS Vaccine Immunology. The center is a National Institutes of Health-sponsored consortium of researchers at UAB, Harvard Medical School in Boston, Oxford University in England, the University of North Carolina in Chapel Hill and Duke University in Durham, N.C.

The new HIV-1 findings are published online in the Proceedings of the National Academy of Sciences.

The new study was performed by sequencing many copies of the HIV envelope gene present in the viruses taken from 102 recently infected patients. The envelope gene encodes for a protein called Env that forms part of the outer covering of the virus, and is responsible for its infectiousness.

The researchers then used sophisticated mathematical models of HIV replication and genetic change to identify the virus or viruses responsible for transmission. In 80 percent of the newly infected patients, a single virus caused transmission, though each virus was different in each patient. In the other 20 percent of patients, two to five unique viruses caused transmission.

“Previously, researchers employed inexact methodologies that prevented precise identification of the virus that initiated infection,” said Brandon Keele, Ph.D., an instructor in UAB’s Department of Medicine and lead study investigator. “Our findings allow us to identify not only the transmitted virus, but also viruses that evolve from it.”

The UAB team said their work would lead to new research on how different HIV genes and proteins work together to make a virus biologically fit for transmission and for growth in the face of mounting immunity.

Statistics show that while the worldwide percentage of people infected with HIV has leveled off, the total number HIV cases is rising. In 2007, 33.2 million people were estimated to be living with HIV, 2.5 million people became newly infected and 2.1 million people died from AIDS, according to the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization.

Source: University of Alabama at Birmingham

Beaded viruses and geology-inspired paintings show the art in science
Holly Wichman found herself an empty-nester with a well-established research lab in 2000, so she used some of her new found time to pursue an artistic activity that paralleled her research. The virologist began making small beaded sculptures in the shapes of viruses that she studies in her lab. Wichman's beaded viruses along with artworks by two other scientists will be displayed at the American Association for the Advancement of Science Gallery starting 16 June.
New HIV browser gives researchers access to valuable data from vaccine trials
A new HIV data browser developed by the University of California, Santa Cruz, and the nonprofit organization Global Solutions for Infectious Diseases (GSID) will give researchers access to a wealth of data collected during clinical trials of an AIDS vaccine. Although the vaccine did not succeed in preventing infections, the clinical trial generated a huge amount of valuable data for researchers studying how the virus evolves and causes new infections.
New treatments for viral and other diseases by blocking genes
The elusive goal of developing effective treatments for viral diseases such as AIDS and influenza has been brought closer by dramatic progress in the ability to interfere with viral genetic machinery. The stage was set for a coordinated European effort to accelerate research and stimulate development of new treatments against viral diseases at a recent research conference organised by the European Science Foundation (ESF).
Scientists reveal a protein's role in enabling AIDS virus to reproduce
A team of scientists at Cold Spring Harbor Laboratory (CSHL) has discovered new details about how a simian strain of the AIDS virus replicates. The findings are significant because they suggest new strategies to prevent replication, and because they are applicable to human strains of the virus, which, despite the persistent efforts of scientists over two decades, can only be slowed by drug treatments but neither cured nor prevented.
Study finds unique HIV vaccine formula elicits strong immune responses
Today, Advanced BioScience Laboratories, Inc. and the University of Massachusetts Medical School report that their unique HIV vaccine formulation was effective in eliciting strong and balanced immune responses in healthy human volunteers.
Scientists 'paint' viruses to track their fate in the body
Biologists from Austria and Singapore developed a technique that adds a new twist on the relationship between biology and art. In an article recently published online in The FASEB Journal and scheduled for the August 2008 print issue, these researchers describe how they were able to coat—or paint—viruses with proteins.
Scientists identify key roadblock to gene expression
A team of scientists has provided, for the first time, a detailed map of how the building blocks of chromosomes, the cellular structures that contain genes, are organized in the fruit fly Drosophila melanogaster. The work identifies a critical stop sign for transcription, the first step in gene expression, and has implications for understanding how the AIDS virus regulates its genes. The findings will be published in the 15 May 2008 issue of the journal Nature.
Bread mold may hold secret to eliminating disease-causing genes
When most people discover mold on their bread, they immediately throw it out. Others see a world of possibilities in the tiny fungus. A University of Missouri scientist, along with a collaborative research team, has examined a new mechanism in the reproductive cycle of a certain species of mold. This mechanism protects the organism from genetic abnormalities by “silencing” unmatched genes during meiosis (sexual reproduction). The finding could have implications for higher organisms and may lead to precise “targeting” of unwanted genes, such as those from the HIV virus.

HIV infection stems from few viruses

Related stories:

News discussion: