Featured Research

from universities, journals, and other organizations

Infection By Closely Related HIV Strains Possible

Date:
December 3, 2002
Source:
NIH/National Institute Of Allergy And Infectious Diseases
Summary:
A report of an individual infected with a second strain of HIV despite effective drug treatment following the first infection has researchers concerned.

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

Related Articles


"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.

Press releases, fact sheets and other NIAID-related materials are available on the NIAID Web site at http://www.niaid.nih.gov.


Story Source:

The above story is based on materials provided by NIH/National Institute Of Allergy And Infectious Diseases. Note: Materials may be edited for content and length.


Cite This Page:

NIH/National Institute Of Allergy And Infectious Diseases. "Infection By Closely Related HIV Strains Possible." ScienceDaily. ScienceDaily, 3 December 2002. <www.sciencedaily.com/releases/2002/12/021203075407.htm>.
NIH/National Institute Of Allergy And Infectious Diseases. (2002, December 3). Infection By Closely Related HIV Strains Possible. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2002/12/021203075407.htm
NIH/National Institute Of Allergy And Infectious Diseases. "Infection By Closely Related HIV Strains Possible." ScienceDaily. www.sciencedaily.com/releases/2002/12/021203075407.htm (accessed October 24, 2014).

Share This



More Health & Medicine News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

IKEA Desk Converts From Standing to Sitting With One Button

IKEA Desk Converts From Standing to Sitting With One Button

Buzz60 (Oct. 24, 2014) IKEA is out with a new convertible desk that can convert from a sitting desk to a standing one with just the push of a button. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com
Ebola Protective Suits Being Made in China

Ebola Protective Suits Being Made in China

AFP (Oct. 24, 2014) A factory in China is busy making Ebola protective suits for healthcare workers and others fighting the spread of the virus. Duration: 00:38 Video provided by AFP
Powered by NewsLook.com
WHO: Millions of Ebola Vaccine Doses by 2015

WHO: Millions of Ebola Vaccine Doses by 2015

AP (Oct. 24, 2014) The World Health Organization said on Friday that millions of doses of two experimental Ebola vaccines could be ready for use in 2015 and five more experimental vaccines would start being tested in March. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Doctor in NYC Quarantined With Ebola

Doctor in NYC Quarantined With Ebola

AP (Oct. 24, 2014) An emergency room doctor who recently returned to the city after treating Ebola patients in West Africa has tested positive for the virus. He's quarantined in a hospital. (Oct. 24) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins