Like most persistent viruses, HIV uses a variety of strategies to counteract its hosts response to infection. HIV infects the very cells that coordinate the immune response, which compromises the immune system and leaves the body susceptible to normally harmless microorganisms. It is these opportunistic infections, rather than the virus itself, that make HIV so deadly. Victor Appay and colleagues now show that an important effect of persistent HIV infection is generally elevated immune activation. Rather than being beneficial to the host, this causes non-specific premature maturation of many of the remaining functional T-cells. The resulting premature aging and exhaustion of the immune system increase the likelihood of opportunistic infection.
HIV targets white blood cells with surface receptors called CD4. These CD4, or helper, T-cells normally orchestrate the bodys immune response. In response to a particular pathogen, they induce cytotoxic T-cells (or CD8 T-cells) and other immune cells to multiply and differentiate--that is, to become specially equipped to recognize and target a particular pathogen, or antigen. When the researchers analyzed T-cells from a group of untreated HIV infected individuals at different stages--acute infection, chronic infection without progression, and chronic infection with signs of progression--they found to their surprise that during acute HIV infection, the vast majority (80%–90%) of the overall CD8 T-cell population was activated--not just the HIV-specific CD8 T-cells. CD8 T-cells specific to two other chronic (and usually benign) pathogens, Epstein–Barr virus and cytomegalovirus, showed significant activation levels during HIV acute infection. And as HIV/AIDS progresses, many of the CD8 T-cells developed to a state of senescence where they are no longer active.
These results show that chronic and nonspecific overactivation of the immune system during HIV infection produces a large pool of highly differentiated T-cells which exhibit characteristics associated with "replicative senescence"--they are in effect old, worn-out cells that can no longer proliferate and fight pathogens effectively.
Barbara Cohen | EurekAlert!
NIH scientists describe potential antibody treatment for multidrug-resistant K. pneumoniae
14.03.2018 | NIH/National Institute of Allergy and Infectious Diseases
Researchers identify key step in viral replication
13.03.2018 | University of Pittsburgh Schools of the Health Sciences
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences