Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cause of hepatitis A virulence pinpointed

09.08.2002


Researchers at the National Institute of Allergy and Infectious Diseases (NIAID) have located two genes that give hepatitis A virus (HAV) its virulent properties. The team, led by Suzanne Emerson, Ph.D., also has discovered that deliberately weakened HAV can quickly revert to its naturally occurring, infection-causing form. To be published in the September 1 issue of Journal of Virology, and appearing online this week, these findings indicate that making an improved vaccine for HAV will be a very difficult task.



"As sanitation improves in developing countries, there will be an increased need for inexpensive and easy-to-administer vaccines to prevent hepatitis A, which is transmitted through contaminated food and water," notes Dr. Emerson. HAV is so common in developing countries that almost everyone is infected during childhood (often without becoming noticeably ill) and thereafter is immune to the virus. Improvements in sanitation and water quality, though, make such naturally acquired immunity less likely. Unfortunately, if HAV infection occurs for the first time later in life, it can result in dangerous illness, including severe liver damage.

A vaccine made from killed HAV does exist, but it requires multiple booster shots to be given intramuscularly-an expense and inconvenience that inhibits its use in less developed countries. Scientists at NIAID have been attempting to develop a live, attenuated HAV vaccine. An attenuated vaccine-one made from a deliberately weakened form of the virus-could be given orally in a single dose, a clear advantage to the existing vaccine.


To develop such a vaccine, Dr. Emerson and her coworkers first had to determine which genes give HAV its punch. They compared the genetic make-up of a virulent version of human HAV with that of an attenuated version of the same strain of virus by creating 14 artificial "chimeric" viruses, each of which contained a different combination of genes taken from the parent strains. Monkeys exposed to a virus that contained either of two genes, 2C or VP1/2A, from the virulent parent developed symptoms of hepatitis. When both genes from the virulent parent were present, the disease was markedly more severe. Conversely, chimeras containing mutated forms of 2C and VP1/2A did not cause disease.

Weakening HAV by altering its two virulence-determining genes would seem to be a logical way to produce a hepatitis A vaccine. But when the researchers infected monkeys with just such an attenuated virus, it mutated within those animals, although it did not cause disease. Feces from the animals, however, contained infectious particles that could cause hepatitis in other monkeys.

"Although these results suggest that a live, attenuated HAV vaccine may be difficult to develop, they do help us better understand what controls HAV growth," notes Dr. Emerson. "Ultimately, this knowledge may provide us with a roadmap to a less expensive and more potent killed vaccine that could be used worldwide."


NIAID is a component of the National Institutes of Health (NIH). 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: SU Emerson et al. Identification of VP1/2A and 2C as virulence genes of hepatitis A and demonstration of genetic instability of 2C. Journal of Virology. 76 (17), pp. 8551-59 (2002).
Available online at http://jvi.asm.org/.

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

The National Institute of Allergy and Infectious Diseases
is a component of the National Institutes of Health,
U.S. Department of Health and Human Services

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

More articles from Health and Medicine:

nachricht Laser activated gold pyramids could deliver drugs, DNA into cells without harm
24.03.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences

nachricht What does congenital Zika syndrome look like?
24.03.2017 | 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

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>