HIV exports viral protein in cellular packages

February 15, 2018, University of North Carolina at Chapel Hill School of Medicine
High magnification fluorescence microscopy of HIV Nef in green and CD81-mCherry in red. CD81 is a marker for maturing vesicles that may be exported. In blue are the nuclei. Arrows point to areas where HIV-Nef and CD81 co-localize. Credit: Ryan McNamara

HIV may be able to affect cells it can't directly infect by packaging a key protein within the host's cellular mail and sending it out into the body, according to a new study out of a University of North Carolina Lineberger Comprehensive Cancer Center laboratory.

Researchers reported in the journal mBio that the virus uses secreted cellular packages called exosomes to send the viral Nef into the body. Researchers are planning to continue to investigate the role of the protein outside of infected immune cells, since they believe it's being sent out for a purpose.

"This study establishes that an HIV protein called Nef circulates independently of the virus itself," said UNC Lineberger's Dirk Dittmer, Ph.D., professor in the UNC School of Medicine Department of Microbiology & Immunology. "This could explain how HIV affects cells that it cannot ordinarily infect, such as endothelial cells of the blood-brain barrier."

HIV, or the , attacks a person's immune system by infecting disease-fighting white blood cells called T-cells or macrophages. While other proteins are involved in the virus' ability to infect these and replicate, researchers say Nef plays a role in preventing reinfection of the same white blood cell by two different HIV viruses, and in preventing recognition of the virus by the immune system.

The protein has also been shown to play a role in the disease's progression to AIDS, the late stage of HIV infection in which destruction of the immune system allows opportunistic diseases and cancers to overwhelm the host. Researchers believe Nef's transfer by exosomes could be a mechanism by which the accelerates AIDS progression.

"For many years, the role of Nef has been studied in the context of infected ," said Ryan P. McNamara, Ph.D., the study's first author and a postdoctoral research associate at UNC Lineberger. "What we identified is that the protein is being secreted from without the viral genetic material. This points toward a role for the protein outside of the cell. We believe it's being trafficked outside the cell for a purpose."

Dittmer, who is co-director of UNC Lineberger's global oncology and virology programs, said that based on the finding, researchers also believe Nef could be used as a biomarker. Finding high levels of Nef-containing exosomes in a blood sample, or "liquid biopsy," could be an indication of the start of clinical AIDS, or long-term complications of HIV infection.

"Exosomes in general are of interest in cancer and many diseases beyond HIV infection," Dittmer said. "We will continue our methods to understand their fundamental biology, how it is changed by diseases and how this new molecular entity can be used as a minimally invasive biomarker or liquid biopsy."

Explore further: Tick exosomes may aid transmission of viruses to vertebrates

More information: Ryan P. McNamara et al. Nef Secretion into Extracellular Vesicles or Exosomes Is Conserved across Human and Simian Immunodeficiency Viruses, mBio (2018). DOI: 10.1128/mBio.02344-17

Related Stories

Tick exosomes may aid transmission of viruses to vertebrates

January 4, 2018
Scientists have shown for the first time that exosomes from tick cells can aid transmission of viral proteins and genetic material from arthropod to vertebrate host cells, according to new research published in PLOS Pathogens.

Viral protein may help chickenpox virus spread within the body

May 25, 2017
The virus that causes chickenpox—varicella zoster virus (VZV)—possesses a protein that could enhance its ability to hijack white blood cells and spread throughout the body, according to new research published in PLOS ...

A viral protein that helps EBV-infected B cells to escape human killer T cells

June 11, 2015
About 90% of adults worldwide are infected with Epstein-Barr virus, or EBV. The virus infects B cells (the white blood cells that make antibodies) and can contribute to B-cell-derived cancers, but in most people it remains ...

How do Ebola virus proteins released in exosomes affect the immune system?

March 16, 2017
Cells infected by the deadly Ebola virus may release viral proteins such as VP40 packaged in exosomes, which, as new research indicates, can affect immune cells throughout the body impairing their ability to combat the infection ...

Recommended for you

FRESH program combines basic science with social benefits for women at risk of HIV

September 14, 2018
A program established by investigators from the Ragon Institute of Massachusetts General Hospital (MGH), MIT and Harvard is addressing the persistently elevated risk of HIV infection among young women in South Africa from ...

New study finds HIV outbreak in Indiana could have been prevented

September 13, 2018
An HIV outbreak among people who inject drugs in Indiana from 2011 to 2015 could have been avoided if the state's top health and elected officials had acted sooner on warnings, a new study by the Yale School of Public Health ...

Largest study of 'post-treatment controllers' reveals clues about HIV remission

September 13, 2018
Most HIV patients need to take daily anti-retroviral therapy—if they suspend treatment, HIV will rebound within 3-4 weeks. But clinical trials have revealed that a small fraction of patients can stop taking medications ...

Very few sexually active gay and bisexual men use prophylactic drug to prevent HIV transmission, study finds

September 12, 2018
Only 4 percent of sexually active gay and bisexual men in the United States use Truvada, a highly effective medication used to prevent the transmission of HIV, according to the results of a first-of-its-kind study.

Special antibodies could lead to HIV vaccine

September 10, 2018
Around one percent of people infected with HIV produce antibodies that block most strains of the virus. These broadly acting antibodies provide the key to developing an effective vaccine against HIV. Researchers from the ...

Researchers date 'hibernating' HIV strains

September 5, 2018
Researchers at the BC Centre for Excellence in HIV/AIDS (BC-CfE) and Simon Fraser University (SFU), in partnership with University of British Columbia (UBC) and Western University, have developed a novel way for dating "hibernating" ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.