Researchers find a peptide that encourages HIV infection

May 10, 2007

UCLA AIDS Institute researchers have discovered that when a crucial portion of a peptide structure in monkeys that defends against viruses, bacteria and other foreign invaders is reversed, the peptide actually encourages infection with HIV.

The findings, published in the April issue of AIDS Research and Human Retroviruses, could pave the way for the use of such peptides in gene therapy using HIV-based vectors as the delivery method.

"Although it may seem counterintuitive to value or even study a peptide that increases the ability of HIV-1 to enter a broad range of human cells, retroviral vectors are currently being explored as vehicles for gene therapy," the authors wrote. "In this area, at least, agents that enhance retroviral uptake could contribute to an emerging field of medicine."

"So many people have tried to deliver genes into different kinds of cells," said study co-author Shen Pang, adjunct associate professor at the UCLA School of Dentistry and a member of the UCLA AIDS Institute. "If you know of some method that can enhance gene delivery, you would have a useful tool."

Retrocyclin-1 (RC-100) is a circular peptide that has been shown in previous studies to inhibit the infection of CD4 cells with HIV. RC-111 is also cyclic and has the same amino acid sequence as retrocyclin-1. In both peptides, the amino acids are strung like 18 beads along the molecule's backbone. The amino acids in RC-111, however, are in reverse order.

The researchers had initially wanted to quantify previous research by Dr. Robert I. Lehrer, distinguished professor of medicine in the division of infectious diseases at the David Geffen School of Medicine at UCLA and a co-author of the present study. Unexpectedly, the researchers discovered that while retrocyclin-1 inhibited infection of CD4 cells with HIV-1 by about 95 percent, the RC-111 variant enhanced viral infection five-fold.

There are three structural varieties of peptides, also known as defensins — alpha, beta and theta, Lehrer said. Humans have only alpha and beta; monkeys have all three.

"Here's a peptide whose normal structure allows it to protect against viruses, yet if you make the same peptide and place its amino acids in a reverse order, that lets the virus in," Lehrer said. "We would like to learn why it happens, but at the moment there's no explanation for this paradoxical result."

Still, the findings seem to show promise in gene therapy.

Source: University of California - Los Angeles

Explore further: Computerized counseling reduces HIV-1 viral load, sexual transmission risk

add to favorites email to friend print save as pdf

Related Stories

Synthetic gene circuits pump up cell signals

Apr 08, 2014

(Phys.org) —Synthetic genetic circuitry created by researchers at Rice University is helping them see, for the first time, how to regulate cell mechanisms that degrade the misfolded proteins implicated ...

Amino acid fingerprints revealed in new study

Apr 06, 2014

Some three billion base pairs make up the human genome—the floor plan of life. In 2003, the Human Genome Project announced the successful decryption of this code, a tour de force that continues to supply ...

Some long non-coding RNAs are conventional after all

Apr 04, 2014

Not so long ago researchers thought that RNAs came in two types: coding RNAs that make proteins and non-coding RNAs that have structural roles. Then came the discovery of small RNAs that opened up whole new areas of research. ...

Ancient buried treasure found in daisy seeds

Mar 31, 2014

(Phys.org) —By tracing the evolutionary origin of a drug-like protein ring found in sunflowers, Australian and US scientists have discovered a diverse, 18-million-year-old group of buried proteins in daisy ...

Detour leads to antibiotic resistance

Mar 28, 2014

Ludwig Maximilian University researchers have used cryo-electron microscopic imaging to characterize the structural alterations in the bacterial ribosome that are required for induction of resistance to the ...

Recommended for you

HIV battle must focus on hard-hit streets, paper argues

Apr 10, 2014

In U.S. cities, it's not just what you do, but also your address that can determine whether you will get HIV and whether you will survive. A new paper in the American Journal of Public Health illustrates the ef ...

User comments : 0

More news stories

Low Vitamin D may not be a culprit in menopause symptoms

A new study from the Women's Health Initiative (WHI) shows no significant connection between vitamin D levels and menopause symptoms. The study was published online today in Menopause, the journal of The North American Menopa ...

Astronomers: 'Tilt-a-worlds' could harbor life

A fluctuating tilt in a planet's orbit does not preclude the possibility of life, according to new research by astronomers at the University of Washington, Utah's Weber State University and NASA. In fact, ...