Hepatitis B: Unusual virus discovered in shrews

August 02, 2019

The discovery of an unusual hepatitis B virus from shrews offers new opportunities of better understanding the chronic progression of the disease. International research teams were able to demonstrate that an important protein which is essential for the development of a chronic course of infection is not present in this virus. DZIF scientists at the Charite - Universitaetsmedizin Berlin and the University of Giessen are leading the research.

Infection with the hepatitis B virus (HBV) is one of the major global health problems. The high number of chronic cases is particularly problematic: More than 240 million people around the world are chronically infected with this virus and over 887,000 of those infected die each year of the long-term consequences such as liver cirrhosis and liver cancer. The chronification of HBV infection that often goes undetected for decades is one of the fundamental characteristics of this virus. "Discovering this unusual HBV in shrews gives us an opportunity to better understand the pathogenesis of this chronic illness," explains lead author of the study Andrea Rasche, scientist at the Charite - University Medicine Berlin and DZIF scholarship holder of the "Maternity Leave" programme.

An important protein that is required for the chronification of the infection is not present in the virus in shrews. "Without this immunomodulator, HBeAg, the disease could not become chronic," emphasises Prof. Dr. Jan Felix Drexler, DZIF scientist at the Charite - University Medicine Berlin and DZIF researcher in the research field "Emerging Infections". And this applies to all known HBVs in mammals. They form this protein during the infection. This immunomodulator suppresses the body's specific immune response to HBV so that the infection cannot heal and becomes chronic - often with very high viral concentrations in the blood. When this viral protein is not present, the body's immune system can successfully fight the infection.

This is not the case with the newly discovered HBV in shrews. The researchers examined almost 700 shrew samples from Europe and Africa and despite the absence of HBeAg, those animals that were infected still showed high concentrations of HBV in the blood. "This indicates a very successful but unusual characteristic of the infection and the transmission of shrew HBV in its host," explains Prof. Dr. Dieter Glebe, head of the National Reference Centre for Hepatitis B and D viruses at the Justus Liebig University of Giessen (JLU) and DZIF scientist in the research field "Hepatitis". "Since the virus cannot infect human liver cells, it is highly unlikely that the virus can infect people." Therefore, it can be reasonably concluded that there is no risk for humans if they come into contact with shrews infected with HBV.

Another characteristic of the newly discovered virus is that it does not use the liver bile acid transporter to enter the liver cells as is the case with HBV in humans and apes, but takes an unknown path into the cell. "This shows that we still do not know all HBV receptor molecules," explains Prof. Drexler. In addition to these important findings about the HBV infection, the shrew virus gives us new insight into the genealogy of HBV. "Our evolutionary studies show that HBV exists in mammals for millions of years, probably around 80 million years," says Prof. Drexler.

The scientists now want to further examine the unusual infection pattern of shrew HBV that develops without the central immunomodulator HBeAg. Despite intensive international efforts, an effective treatment for chronic hepatitis B has yet to be developed. One reason for this is that there are no suitable animal models that can be used to examine the complex interactions of the virus infection with the host's immune system. "Shrews could be a promising animal model for HBV research. The virus discovered here is particularly suitable for examining the mechanisms of chronic HBV infections," says Prof. Drexler.
International collaboration

Together with the teams led by Prof. Dr. Dieter Glebe and Prof. Dr. Jan Felix Drexler, many national and international research teams are involved in the study. The work was primarily funded by the German Research Foundation (DFG) and as part of the German Centre for Infection Research (DZIF). JLU, the Charite - Universitätsmedizin Berlin, the Bernhard Nocht Institute for Tropical Medicine in Hamburg, the Friedrich Loeffler Institute in Greifswald/Riems as well as universities and institutes in Brazil, the Netherlands, Sierra Leone, Nigeria, the Ivory Coast, Latvia, Lithuania and Russia are involved in the study.


Rasche et al.: Highly diversified shrew hepatitis B viruses corroborate ancient origins and divergent infection patterns of mammalian hepadnaviruses.
PNAS August 1, 2019
DOI: 10.1073/pnas.1908072116


Prof. Dr. Jan Felix Drexler
Charité - Universitaetsmedizin Berlin and
DZIF research field "Emerging Infections"
Telephone: +49 (0)30 450 625461
E-mail: felix.drexler@charite.de

Prof. Dr. Dieter Glebe
National Reference Centre for Hepatitis B and D Viruses
Institute of Virology of the University of Giessen and
DZIF research field "Hepatitis"
Telephone: +49 (0)641 99-41246
E-mail: dieter.glebe@viro.med.uni-giessen.de

Andrea Rasche
Charité - Universitaetsmedizin Berlin and
DZIF research field "Emerging Infections"
Telephone: +49 (0)30 450 525466
E-mail: andrea.rasche@charite.de

German Center for Infection Research

Related Science Articles from Brightsurf:

75 science societies urge the education department to base Title IX sexual harassment regulations on evidence and science
The American Educational Research Association (AERA) and the American Association for the Advancement of Science (AAAS) today led 75 scientific societies in submitting comments on the US Department of Education's proposed changes to Title IX regulations.

Science/Science Careers' survey ranks top biotech, biopharma, and pharma employers
The Science and Science Careers' 2018 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.

Science in the palm of your hand: How citizen science transforms passive learners
Citizen science projects can engage even children who previously were not interested in science.

Applied science may yield more translational research publications than basic science
While translational research can happen at any stage of the research process, a recent investigation of behavioral and social science research awards granted by the NIH between 2008 and 2014 revealed that applied science yielded a higher volume of translational research publications than basic science, according to a study published May 9, 2018 in the open-access journal PLOS ONE by Xueying Han from the Science and Technology Policy Institute, USA, and colleagues.

Prominent academics, including Salk's Thomas Albright, call for more science in forensic science
Six scientists who recently served on the National Commission on Forensic Science are calling on the scientific community at large to advocate for increased research and financial support of forensic science as well as the introduction of empirical testing requirements to ensure the validity of outcomes.

World Science Forum 2017 Jordan issues Science for Peace Declaration
On behalf of the coordinating organizations responsible for delivering the World Science Forum Jordan, the concluding Science for Peace Declaration issued at the Dead Sea represents a global call for action to science and society to build a future that promises greater equality, security and opportunity for all, and in which science plays an increasingly prominent role as an enabler of fair and sustainable development.

PETA science group promotes animal-free science at society of toxicology conference
The PETA International Science Consortium Ltd. is presenting two posters on animal-free methods for testing inhalation toxicity at the 56th annual Society of Toxicology (SOT) meeting March 12 to 16, 2017, in Baltimore, Maryland.

Citizen Science in the Digital Age: Rhetoric, Science and Public Engagement
James Wynn's timely investigation highlights scientific studies grounded in publicly gathered data and probes the rhetoric these studies employ.

Science/Science Careers' survey ranks top biotech, pharma, and biopharma employers
The Science and Science Careers' 2016 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.

Three natural science professors win TJ Park Science Fellowship
Professor Jung-Min Kee (Department of Chemistry, UNIST), Professor Kyudong Choi (Department of Mathematical Sciences, UNIST), and Professor Kwanpyo Kim (Department of Physics, UNIST) are the recipients of the Cheong-Am (TJ Park) Science Fellowship of the year 2016.

Read More: Science News and Science Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.