Researchers at Helmholtz Zentrum München, Technical University of
Munich (TUM) and the German Center for Infection Research (DZIF) have
developed a novel therapeutic approach to cure chronic hepatitis B. The
scientists found that the large amount of hepatitis B virus proteins
expressed in the liver prevents the body’s immune system to defeat the
virus, consequently preventing an effective therapy. The researchers
were able to show that knocking down the expression of the virus’
proteins enables successful vaccination with TherVacB, a novel
therapeutic vaccine.
Around 260 million humans, more than three percent of the world’s
population, are chronically infected by the hepatitis B virus. As a
result, every year, 880,000 people worldwide die of liver failure or
hepatocellular carcinoma. Currently no curative therapy is available.
The therapies available to date inhibit virus replication, but need to
be given long-term. As long as infected people cannot form an adequate
immune response, the virus will survive. This is precisely where Prof.
Ulrike Protzer, head of the Institute of Virology at Helmholtz Zentrum
München and TUM, and her team start.
Novel therapeutic approach
Using a preclinical mouse model, the researchers found that proteins
of the hepatitis B virus prevent that certain immune cells of the body,
so-called CD8+ T-cells become effective. Based on these finding, the
scientists developed a novel therapeutic approach: first, the expression
levels of the virus proteins are knocked down, and then the immune
cells are activated by therapeutic vaccination. In contrast to
conventional vaccinations, which aim to prevent diseases before
outbreak, such a therapeutic vaccination aims to cure already existing
chronic diseases.
Successful suppression of virus proteins in mice
Consequently, the researchers first developed a method to suppress
the hepatitis B virus proteins. They used siRNAs, small ribonucleic acid
molecules that bind to the messenger RNA of the virus’ proteins. By
labelling the messenger RNA with siRNA, the infected cell receives the
signal that the viral RNA is undesired and removes it. In this way
protein expression is knocked down. However, the suppression of protein
expression alone was not sufficient to reverse the inhibition of the
CD8+ T-cells in chronically infected mice.
Infection cured in mice
The scientists therefore had to go one step further: “We then
combined the siRNA method with a therapeutic vaccination developed by
us. This enabled us to trigger a strong immune response against the
virus. This led to cure of hepatitis B virus infection in two different
mouse models,” explains Dr. Thomas Michler, physician and one of the two
first authors of the study.
Novel therapeutic vaccination soon in a clinical trial
The newly developed vaccine, called TherVacB, will be tested as an
immunotherapy in a two-year clinical trial starting in 2021. “The
therapeutic vaccine we have developed is indeed very promising as it
induces neutralizing antibodies and T-cell responses,” said Dr. Anna
Kosinska, the other first author of the study. The vaccine will be
administered in three doses every four weeks. It has been designed to
target the majority of all hepatitis B viruses and therefore will be
beneficial to most people infected worldwide.
“We are very pleased that for the clinical trials of TherVacB we are
able to cooperate with a consortium of Europe’s leading virologists,
immunologists and hepatologist, guided by Helmholtz Zentrum München,”
adds Protzer. The consortium will receive funding of more than € 10
million from the European Union within the program Horizon 2020
(H2020-SC1-2019).
###
Original publication
T. Michler et al., 2020: Knockdown of Virus Antigen Expression
Increases Therapeutic Vaccine Efficacy in High-titer HBV Carrier Mice.
Gastroenterology, DOI: 10.1053/j.gastro.2020.01.032.
Helmholtz Zentrum München, the German Research Center for
Environmental Health, pursues the goal of developing personalized
medical approaches for the prevention and therapy of major common
diseases such as diabetes, allergies and lung diseases. To achieve this,
it investigates the interaction of genetics, environmental factors and
lifestyle. The Helmholtz Zentrum München is headquartered in Neuherberg
in the north of Munich and has about 2,500 staff members. It is a member
of the Helmholtz Association, a community of 19 scientific-technical
and medical-biological research centers with a total of about 37,000
staff members.
http://www.helmholtz-muenchen.de/en
The Institute of Virology (VIRO) investigates viruses that
chronically infect humans and can cause life-threatening diseases. The
research activities of the institute focus mainly on the HI virus which
causes AIDS, on endogenous retroviruses, which are integrated into our
germline, and hepatitis B and C viruses, which cause liver cirrhosis and
hepatocellular carcinoma. Molecular studies identify new diagnostic and
therapeutic concepts to prevent and treat these viral diseases or to
prevent the formation of virus-induced tumors.
http://www.helmholtz-muenchen.de/viro
https://www.eurekalert.org/pub_releases/2020-02/hzm–hbn020320.php