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 When added to gene therapy, plant-based compound may enable faster, more effective treatments
18.10.2019 | Scripps Research Institute

nachricht Diabetes: A next-generation therapy soon available?
17.10.2019 | Université de Genève

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: Solving the mystery of quantum light in thin layers

A very special kind of light is emitted by tungsten diselenide layers. The reason for this has been unclear. Now an explanation has been found at TU Wien (Vienna)

It is an exotic phenomenon that nobody was able to explain for years: when energy is supplied to a thin layer of the material tungsten diselenide, it begins to...

Im Focus: An ultrafast glimpse of the photochemistry of the atmosphere

Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

The nanocosmos is constantly in motion. All natural processes are ultimately determined by the interplay between radiation and matter. Light strikes particles...

Im Focus: Shaping nanoparticles for improved quantum information technology

Particles that are mere nanometers in size are at the forefront of scientific research today. They come in many different shapes: rods, spheres, cubes, vesicles, S-shaped worms and even donut-like rings. What makes them worthy of scientific study is that, being so tiny, they exhibit quantum mechanical properties not possible with larger objects.

Researchers at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Argonne National...

Im Focus: Novel Material for Shipbuilding

A new research project at the TH Mittelhessen focusses on the development of a novel light weight design concept for leisure boats and yachts. Professor Stephan Marzi from the THM Institute of Mechanics and Materials collaborates with Krake Catamarane, which is a shipyard located in Apolda, Thuringia.

The project is set up in an international cooperation with Professor Anders Biel from Karlstad University in Sweden and the Swedish company Lamera from...

Im Focus: Controlling superconducting regions within an exotic metal

Superconductivity has fascinated scientists for many years since it offers the potential to revolutionize current technologies. Materials only become superconductors - meaning that electrons can travel in them with no resistance - at very low temperatures. These days, this unique zero resistance superconductivity is commonly found in a number of technologies, such as magnetic resonance imaging (MRI).

Future technologies, however, will harness the total synchrony of electronic behavior in superconductors - a property called the phase. There is currently a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Symposium on Functional Materials for Electrolysis, Fuel Cells and Metal-Air Batteries

02.10.2019 | Event News

NEXUS 2020: Relationships Between Architecture and Mathematics

02.10.2019 | Event News

Optical Technologies: International Symposium „Future Optics“ in Hannover

19.09.2019 | Event News

 
Latest News

Energy Flow in the Nano Range

18.10.2019 | Power and Electrical Engineering

MR-compatible Ultrasound System for the Therapeutic Application of Ultrasound

18.10.2019 | Medical Engineering

Double layer of graphene helps to control spin currents

18.10.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>