Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Infection by closely related HIV strains possible

28.11.2002


A report of an individual infected with a second strain of HIV despite effective drug treatment following the first infection has researchers concerned.



"For the first time, we’ve shown it is possible for an individual to become infected with two closely related strains of HIV," says Bruce D. Walker, M.D., a grantee of the National Institute of Allergy and Infectious Diseases (NIAID) and a researcher at Massachusetts General Hospital and Harvard Medical School.

Published in this week’s issue of Nature, these findings underscore the challenges vaccine developers face in creating a broadly effective vaccine against HIV. The first HIV vaccines may not prevent infection altogether, but rather may prevent HIV from causing disease by limiting the virus’ ability to reproduce, explains Dr. Walker. This case shows that a hypothetical vaccine against one strain of HIV may not necessarily protect the vaccinee against other, closely related strains.


"The implications of superinfection for an individual with HIV/AIDS are not yet clear," says Anthony S. Fauci, M.D., NIAID’s director. "However, there is little doubt what these new data mean in terms of public health: It is imperative that safer sex be practiced during each encounter, even when both partners are HIV-infected," he adds.

The new case involves a person whose HIV infection was kept in check for many months during structured treatment interruption (STI). In STI, antiviral therapies are frequently given during the early, acute stage of infection, but halted after the immune system has had time to adapt to the virus. Often, as in this case, a patient’s immune system rebounds enough to keep HIV suppressed. "This patient’s immune response against HIV was really quite robust," says Dr. Walker. Thus, the researchers were perplexed when, after successfully suppressing HIV for close to one year, the patient’s viral load suddenly shot upwards. Despite several more attempts to interrupt therapy, the patient was unable to hold the virus to previously attained low levels.

To understand why STI stopped working for this individual, "We dissected the immune system in very fine detail," says Dr. Walker. First, he and his co-investigators examined HIV-made proteins taken from the patient at several points in time. They detected a difference between the amino acid sequence of the original infecting virus and the virus isolated after STI failed. Additional studies confirmed that the change resulted from infection by a second HIV strain well after the first infection.

The two strains differed in overall amino acid sequence by about 12 percent, "about what we’d expect for two strains in North America," notes Dr. Walker. In comparison, the sequence difference between strains of various major subtypes, or clades, of HIV is about 30 percent. Although superinfection by strains from different clades has been reported previously, this is the first published report of infection by two strains from the same clade.

The picture became still more sobering when the researchers compared only those HIV amino acid sequences targeted by the immune system. Here, the strains differed by 50 percent. Consequently, a large fraction of the immune cells that had been produced previously and that had successfully tamped down the first virus were unable to recognize and react to the second strain. "We were stunned," says Dr. Walker. "Essentially, the immune system was encountering two markedly different viruses."

The research did uncover a few bright spots, however. For instance, immune system cells called CD8+ T cells, appeared in new, strain-specific forms after the individual became infected with the second strain. This indicates an ability on the part of the CD8+ T cells to react appropriately to newly arrived HIV strains, even in conditions of chronic infection. Thus, researchers can remain cautiously optimistic that therapeutic immunization to create broader and more potent immune responses in persons with chronic HIV infection may one day be possible.


NIAID is a component of the National Institutes of Health (NIH), which is an agency of the Department of Health and Human Services. NIAID supports basic and applied research to prevent, diagnose, and treat infectious and immune-mediated illnesses, including HIV/AIDS and other sexually transmitted diseases, illness from potential agents of bioterrorism, tuberculosis, malaria, autoimmune disorders, asthma and allergies.

Reference: M Altfeld et al. HIV-1 superinfection despite broad CD8+ T-cell responses containing replication of the primary virus. Nature 240:434-39 (2002).

Anne Oplinger | EurekAlert!
Further information:
http://www.niaid.nih.gov/

More articles from Health and Medicine:

nachricht Vanishing capillaries
23.03.2017 | Technische Universität München

nachricht How prenatal maternal infections may affect genetic factors in Autism spectrum disorder
22.03.2017 | University of California - San Diego

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short

23.03.2017 | Life Sciences

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>