Example: Characterization of HERV envelope proteins with the aim of developing therapeutic antibodies for HERV-associated autoimmune and tumor diseases
For the last few years, our main interest has been to uncover the interaction of viruses and viral derived elements with the human immune system in the context of pathogenesis of autoimmune diseases. Our studies center on human endogenous retroviruses (HERVs). We have used and developed techniques to study genetic association of HERVs with a disease and to monitor functional consequences of their expression.
Human endogenous retroviruses (HERVs) integrated into human germ line cells 70-30 million years ago, becoming part of the human DNA and being transmitted through the generations. They represent up to 8% of the human genome. HERVs have the same genetic structure as exogenous retroviruses. Two LTR (long terminal repeat) regions delimit the genome that encodes four major viral proteins: Gag, the matrix and retroviral core: Pol, the reverse transcriptase; Pro, the integrase; and Env, the envelope.
Despite the accumulation of mutations, stop codons and epigenetic mechanisms to silence their genetic expression, HERVs are still contributing to the human transcriptome, and a growing number of findings suggest that their expression products may, in addition to their roles in normal physiology, play pathogenic roles in various diseases.
Figure source: Viruses | Free Full-Text | Type W Human Endogenous Retrovirus (HERV-W) Integrations and Their Mobilization by L1 Machinery: Contribution to the Human Transcriptome and Impact on the Host Physiopathology | HTML (mdpi.com)
Figure legend: The exogenous retroviruses that gave rise to HERVs were also able to infect germ line cells. In this way, the integrated HERV sequences have been inherited in a Mendelian fashion, being vertically transmitted through the offspring and fixed into the human genome. During evolution, the majority of HERVs accumulated mutations that generally compromised their coding capacity.
Example: Development of a platform technology useful for design and production of immune modulatory peptides derived from endogenous retroviruses
Our group has developed a platform technology useful for design and production of immune modulatory peptides derived from endogenous retroviruses. It has been known for many years that retroviral envelope proteins are capable of significant immune suppression activity. This activity is located to a very well-defined structure (the so called ISD) in the retroviral transmembrane (TM) protein which is conserved among the retroviruses of several species (including murine, feline, and human retroviruses such as human T-cell leukemia virus). ISDs have been identified in both exogenous and endogenous retroviruses.
During the past years we have focused on a particular group of immune suppressive peptides which we have shown to be effective in vitro and in vivo in a number of animal models for different autoimmune disease. These include:
The peptides in question are derived from human endogenous retroviral elements and are synthetically produced linear peptides between 15 and 32 amino acid long and containing only genetically encoded amino acids. The library (at present consisting of +150 peptides) with highly specific immune inhibitory or modulating activity profiles, can easily be engineered, functionalized and modified to enhance their bioavailability, stability, specificity, and efficiency. Our future activities will focus on further development of this concept for use in treatment of autoimmunity and/or inflammation.
Figure. Illustration of endogenous retroviral envelope (Env) protein with the immunosuppressive domain. The ISD domain is a part of the transmembrane domain.
Design and production of SARS-CoV-2 and other viruses VLPs as a tool to develop better virus-related diagnostics
Virus like particles (VLPs) are nanostructures that resemble real viruses without being infectious. VLPs are constructed using recombinant DNA technology allowing altering and combining genetic material from different sources.
We use VLPs as platforms for studying the interaction of enveloped viruses with their host cells, focusing on the entry mechanism of viruses. Virus like particles can be designed based on retroviral vector systems or other backbones, which combine genes for formation of the particles with genes involved in mediating the fusion of the virus and the cell membranes (which results in virus entry into host cells) in a trans fashion. Since these genetic elements can be expressed from different independent cassettes, design and production of VLPs containing different reporter genes and decorated with the surface proteins derived from various viruses is a straightforward process, making VLP technologies very useful for research into virus entry mechanisms and inhibitors.
One example of design and application of VLPs is the new SARS-CoV-2 virus that causes COVID-19 conditions. Our group has developed an experimental diagnostic model for assessing the effect of antibodies on the infectivity of SARS-CoV-2 virus that can be easily implemented in standard class 2 laboratory settings. Our model consists of VLPs with a retroviral core decorated with the S protein (the protein on the surface) of the SARS-CoV-2. Thus, the VLP particles, while containing a reporter gene (eGFP), look the same as a corona virus on the surface and at the same time carry no corona virus genetic elements. More importantly, such particles depend on the corona virus S protein for entry into cells, making it useful for testing the neutralization capacity of anti-corona antibodies. This enables us to determine the actual activity of anti-SARS-2 antibodies in inhibiting virus entry as compared to binding affinities measured by ELISA based methods.