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:3/30/2017)... , March 30, 2017 Trends, opportunities and ... and behavioral), by technology (fingerprint, AFIS, iris recognition, facial ... and others), by end use industry (government and law ... financial and banking, and others), and by region ( ... , Asia Pacific , and the ...
(Date:3/28/2017)... 2017 The report "Video Surveillance ... Servers, Storage Devices), Software (Video Analytics, VMS), and Service ... Forecast to 2022", published by MarketsandMarkets, the market was ... projected to reach USD 75.64 Billion by 2022, at ... base year considered for the study is 2016 and ...
(Date:3/24/2017)... The Controller General of Immigration from Maldives Mr. Mohamed Anwar ... the prestigious international IAIR Award for the most innovative high security ePassport ... ... Maldives Immigration Controller General, Mr. ... on the right) have received the IAIR award for the "Most innovative ...
Breaking Biology News(10 mins):
(Date:4/27/2017)... ... April 27, 2017 , ... During the course of ... testing for 1,25-Dihydroxyvitamin D can enhance clinical practice. Participants will learn the medical ... D. , Dr. Gregory Plotnikoff, senior consultant with Minnesota Personalized Medicine, will be ...
(Date:4/27/2017)... April 27, 2017  Pendant Biosciences, Inc. (formerly Nanoferix, ... modification and drug delivery technologies, today announced that it ... @ Toronto . ... Pendant Biosciences, noted, "We are excited to become part ... community, and are honored to be the first ...
(Date:4/26/2017)... ... April 25, 2017 , ... LABS, Inc. (LABS) announced in December 2016 ... extensive test menu: Nucleic Acid Testing (NAT) for ZIKV; and Enzyme Immunoassays (EIAs) specific ... offer NAT screening for blood donors under an Investigational New Drug (IND) study protocol. ...
(Date:4/25/2017)... ... April 25, 2017 , ... As part of the ... explore the laboratory testing for DIC in order to illuminate this clinical problem for ... occur in hospitalized patients resulting in a high degree of morbidity and mortality. DIC ...
Breaking Biology Technology: