Navigation Links
Ancient immune defense mechanism is no match for HIV-1

Researchers have discovered that mammalian cells infected with HIV-1 engage a primitive defense mechanism that was previously observed only in plants and invertebrates. The research also reveals exactly how HIV-1 successfully thwarts this rare form of immunity in vertebrate cells. However, elucidation of the mechanism HIV-1 uses to protect itself provides some critical insight into a potential vulnerability within the HIV-1 molecule. Identification of what might be a long sought after weakness in the virus may have application for rational design of future anti-HIV-1 therapies. The study is published in the May issue of Immunity.

RNA silencing is a type of natural immune defense in which sequence-specific RNA degradation follows the recognition of double-stranded RNA (dsRNA). The dsRNA is processed by a protein called Dicer, which chops the long strands of RNA into smaller pieces, resulting in the production of an RNA-induced silencing complex (RISC). RISC can specifically identify and degrade complementary target RNA. This process is known as RNA interference (RNAi) and can silence the ability of a virus to successfully reproduce itself. Although this mechanism has been artificially manipulated to selectively inhibit specific genes in mammalian cells, it was not known whether mammalian viruses naturally elicit this type of immunity in vertebrate cells.

Drs. Yamina Bennasser and Kuan-Teh Jeang from the Molecular Virology Section at the National Institute of Allergy and Infectious Disease and colleagues found that infection with HIV-1 induces RNAi in human cells. However, the researchers discovered that HIV-1 has an intriguing strategy to combat this cellular defense. The HIV-1 protein Tat, well known as a transcriptional activator, also can function as a suppressor of RNA silencing (SRS). Tat helps HIV-1 to elude the cell's natural RNAi defense by interfering with the ability of Dicer to process dsRNAs.

"Our results suggest that the dynamic in terplay between RNAi and SRS remains physiologically conserved from plants and invertebrates to higher vertebrate animals," explains Dr. Jeang. "Our finding that Tat is an SRS also helps explain the long-standing biological observation that when HIV-1 is engineered to be lacking Tat but contains alternative transcriptional activators, it fails to spread productively in human cells." The researchers also suggest that their findings raise a challenge to proposed therapeutic strategies making use of RNAi. "Because HIV-1 evades all other RNAi by point mutations, we reason that its requirement for an SRS is solely to shield this last 'Achilles' heel that we think HIV-1 cannot alter for functional reasons. The sequence we describe may represent a viable target for RNAi that HIV-1 cannot elude by using the point mutation mechanism, " explains Dr. Jeang.

The researchers include Yamina Bennasser and Kuan-Teh Jeang of the National Institute of Allergy and Infectious Diseases; Shu-Yun Le of the National Cancer Institute; and Monsef Benkirane of the Institut de Genetique Humaine, CNRS.

Bennasser, Y., Le, S.-Y., Benkirane, M., and Jeang, K.-T. (2005). Evidence that HIV-1 Encodes an siRNA and a Suppressor of RNA Silencing. Immunity, 22, 607-619. http://www.immunity.com


'"/>

Source:Cell Press


Related biology news :

1. Ancient olfaction protein is shared by many bugs, offering new pest control target
2. Ancient DNA helps clarify the origins of two extinct New World horse species
3. Researchers Discover Ancient Origins Of Tuberculosis-causing Bacteria
4. Ancient DNA confirms single origin of Malagasy primates
5. Ancient anthropoid origins discovered in Africa
6. Ancient trans-Atlantic swarm brought locusts to the New World
7. Ancient humans brought bottle gourds to the Americas from Asia
8. Ancient DNA helps UF researchers unearth potential hemophilia therapy
9. Ancient DNA provides clues to the evolution of social behavior
10. Ancient ants arose 140-168 million years ago
11. Ancient fossil DNA found preserved in crystal
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:2/8/2017)... BEDFORD, Mass., Feb. 7, 2017  Aware, Inc. (NASDAQ: ... services, today reported financial results for its quarter and year ... fourth quarter of 2016 was $3.9 million compared to $6.9 ... the fourth quarter of 2016 was $0.6 million compared to ... in the fourth quarter of 2016 was $0.5 million, or ...
(Date:2/8/2017)... , Feb. 7, 2017 Report Highlights ... by 2021 from $8.3 billion in 2016 at a ... to 2021. Report Includes - An overview of ... market trends, with data from 2015 and 2016, and ... - Segmentation of the market on the basis of ...
(Date:2/7/2017)... , February 7, 2017 ... Global Solutions Corporation [OTC: IDGS], ("Ipsidy" or the "Company") ... electronic transaction processing services, is pleased to announce the ... Company. Effective January 31, 2017, Philip ... of Directors, CEO and President.  An experienced payment industry ...
Breaking Biology News(10 mins):
(Date:2/24/2017)... 24, 2017 Symic Bio, a biopharmaceutical company ... category of therapeutics, announced today the completion of enrollment ... artery disease. The trial will evaluate the safety and ... the reduction of restenosis following angioplasty. ... for SB-030," said Nathan Bachtell , M.D., Chief ...
(Date:2/24/2017)... Feb. 24, 2017 China Cord Blood Corporation (NYSE: ... leading provider of cord blood collection, laboratory testing, hematopoietic ... announced its unaudited financial results for the third quarter ... December 31, 2016. Third Quarter of Fiscal ... quarter of fiscal 2017 increased by 18.6% to RMB200.9 ...
(Date:2/24/2017)... Products, Inc. (NASDAQ: CBPO) ("China Biologic" or the "Company"), a ... its financial results for the fourth quarter and fiscal year ... Total sales in the fourth quarter ... by 13.6% in USD terms to $77.6 million from $68.3 ... Gross profit increased by 13.3% to $46.8 million from $41.3 ...
(Date:2/24/2017)...  OncoSec Medical Incorporated ("OncoSec") (NASDAQ: ONCS), a company ... Opinion Leader event to highlight new clinical data that ... at the upcoming 2017 ASCO-SITC Immuno-Oncology Symposium and the ... held in-person and via live webcast on Tuesday, February ... at the Lotte New York Palace Hotel in ...
Breaking Biology Technology: