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: Condoms 'too small' for Uganda men

add to favorites email to friend print save as pdf

Related Stories

A better understanding of cell to cell communication

Aug 22, 2014

Researchers of the ISREC Institute at the School of Life Sciences, EPFL, have deciphered the mechanism whereby some microRNAs are retained in the cell while others are secreted and delivered to neighboring ...

Recommended for you

Obese British man in court fight for surgery

Jul 11, 2011

A British man weighing 22 stone (139 kilograms, 306 pounds) launched a court appeal Monday against a decision to refuse him state-funded obesity surgery because he is not fat enough.

2008 crisis spurred rise in suicides in Europe

Jul 08, 2011

The financial crisis that began to hit Europe in mid-2008 reversed a steady, years-long fall in suicides among people of working age, according to a letter published on Friday by The Lancet.

New food labels dished up to keep Europe healthy

Jul 06, 2011

A groundbreaking deal on compulsory new food labels Wednesday is set to give Europeans clear information on the nutritional and energy content of products, as well as country of origin.

Overweight men have poorer sperm count

Jul 04, 2011

Overweight or obese men, like their female counterparts, have a lower chance of becoming a parent, according to a comparison of sperm quality presented at a European fertility meeting Monday.

User comments : 0