HIV: Early diagnosis saves lives

Image courtesy of Seth Pincus, Elizabeth Fischer and Austin At hman, National Institute of Allergy and Infectious Diseases, National Institutes of Health

Every year, 50,000 new HIV infections occur in the U.S. Thirty percent of those infections are caused by HIV-positive people who are unaware of their condition. As part of April’s focus on sexually transmitted diseases, the Centers for Disease Control and Prevention are raising awareness on early detection and prevention of HIV. Since HIV is highly contagious in the initial stages, getting tested and treated early can reduce unintended transmission, which is an important step toward eradication.

What are the stages of HIV infection?

Initial stages of HIV infection cause severe flulike symptoms followed by an asymptomatic period that can last up to 10 years. The last stage is the acquired immunodeficiency syndrome, a condition where the immune system is weak enough for opportunistic infections and tumors to occur. Antiretroviral therapy can help manage symptoms and delay the onset of AIDS to prolong life expectancy.

How does HIV affect the immune system?

The virus targets CD4 T cells, which are white blood cells that mount an immune response against pathogens. Once infected with HIV, these cells self-destruct via caspase-1-mediated cell death called pyroptosis. Proinflammatory cytokines, like IL-1β, produced during pyroptosis recruit more CD4 T cells. The ensuing vicious cycle of infection, death and inflammation severely depletes CD4 T cells. When the CD4 T cell count drops below 200 cells/µL, it leads to AIDS.

What are the recent advances in HIV diagnostics?

Latest technologies, such as a microfluidic device powered by a smartphone and a nanopore-based molecular sensor, are geared toward rapid, portable and inexpensive point-of-care diagnostics. Paul LaBarre and colleagues at PATH, a Seattle-based nonprofit organization, developed an electricity-free heater that enables HIV diagnosis in resource-limited countries. The technology, called non-instrumented nucleic acid amplification, or NINA, uses the constant heat generated from an exothermic reaction between an alloy of magnesium and iron and a saline solution to power the conversion of the viral RNA into DNA and then the amplification of the DNA. Subsequent detection is based on the nucleic acid lateral flow technique. The technique, which is similar to a home pregnancy test in principle, relies on the capillary flow of the analyte in a dipstick and uses a visible color change to indicate the presence of the analyte. The technology allows early diagnosis, because it detects viral RNA rather than anti-HIV antibodies that are produced later in response to the infection. The team has developed a prototype based on field tests conducted in remote areas in Zambia, India and Kenya.

 

 

Indumathi Sridharan Indumathi Sridharan earned her bachelor’s degree in bioinformatics in India. She holds a Ph.D. in molecular biochemistry from Illinois Institute of Technology, Chicago. She did her postdoctoral work in bionanotechnology at Northwestern University.