ESR 15 - Elucidation of herpesvirus evasion mechanisms through CRISPR/Cas-mediated engineering of virus and host genes

University Medical Center Utrecht, The Netherlands

 

 

Student: Patrique Praest, Ph.D. fellow

Supervisor: Prof. Emmanuel J.H.J. Wiertz, D.V.M., Ph.D.

Co-supervisor: Assistant Prof. Robert Jan Lebbink, Ph.D.

 

 

Several hundred million years of co-evolution between vertebrates and invading pathogens have shaped the adaptive immune system of the hosts to fight back the unwanted invaders through highly developed defense mechanisms. Herpesviruses manage to dodge this immune response by interfering with one of the central hinges of human adaptive immunity, the major histocompatibility complex (MHC) class I antigen presentation pathway. This pathway is responsible for the presentation of pathogen-derived peptide fragments to patrolling cytotoxic T-cells; upon recognition of a virus-encoded peptide, the cytotoxic T-cells will induce cell death of the infected cell. One of the bottlenecks of this pathway is the loading of peptides onto MHC-I molecules in the endoplasmic reticulum (ER). This task is accomplished by the MHC class I peptide-loading complex (PLC), of which the transporter associated with antigen-processing (TAP) is a key component. Due to its central role it is not surprising that TAP is a highly sought-after target for viral inhibition mechanisms, especially among viruses such as herpesviruses that develop life-long infections.

 

In this project, we aim for a better understanding of the multiple ways herpesviruses evade recognition of the immune system. The focus lies on herpesvirus-encoded TAP inhibitors; four TAP-inhibiting proteins have been identified in herpesviruses so far. To study their function, we want to make use of the CRISPR/Cas-system to knock out specific viral or host genes. Furthermore, new techniques like Cryo-electron-microscopy could give us new insights into structural details of TAP-inhibition by herpesviruses.

 

The ultimate goal of this study is to provide information that will aid the discovery of new antiviral therapies.

 

 


 

Contact details

Emmanuel J.H.J. Wiertz, Professor of Medical Microbiology / Experimental Virology

Department of Medical Microbiology

University Medical Center Utrecht

G04.647

Heidelberglaan 100

3584 CX Utrecht

The Netherlands

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Assistant Prof. Robert Jan Lebbink

Department of Medical Microbiology

University Medical Center Utrecht

G04.522

Heidelberglaan 100

3584 CX Utrecht

The Netherlands

Phone: +31 887 55 0627

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ESR14 - Characterisation of the pro- or antiviral role of cellular proteins induced upon infection with Human Cytomegalovirus

Helmholtz Centre for Infection Research, Braunschweig, Germany

 

Student: Ana Cristina González Pérez, Ph.D. fellow

Supervisor: Prof. Dr. rer. nat. Melanie Brinkmann

 

 

 

Pathogens infiltrate our bodies daily but do not remain undetected. It is our immune system which recognizes these invaders and takes appropriate measures against them.

 

The immune system has several components. One of them, the type interferon (IFN) response, mediated by receptors called pattern recognition receptors (PRR), plays a key role to fight viral infection. Upon detecting nucleic acids of cellular or viral origin at aberrant locations, these receptors induce the secretion of cytokines called type I IFNs. These cytokines then bind to the type I IFN receptor (IFNAR), which is located on the plasma membrane. This leads to the generation of so called interferon stimulated gene products (ISGs). ISGs can directly inhibit viral replication, for example by shutting off protein synthesis. As a consequence, viruses have developed strategies to block the IFN response and/or ISG functions, or even use these antiviral defence systems for their own benefit. One family of viruses is especially well known for hijacking the immune system: the herpesviridae. Herpesviruses have a large DNA genome that encodes multiple proteins. A large portion of these proteins is dedicated to the modulation of the host immune response, allowing the establishment of lifelong latency.

 

Human cytomegalovirus (HCMV) is a herpesvirus that affects both immunocompetent and immunosuppressed individuals. In healthy individuals, HCMV usually causes only mild disease. However, in immunosuppressed individuals such as AIDS or transplant patients, HCMV infection can cause severe complications such as mononucleosis-like syndrome, encephalitis, retinitis, pneumonia, hepatitis and gastroenteritis. Another risk group are unborn children: HCMV infection during pregnancy can be transmitted from mother to child and can cause severe long-term sequelae such as hearing loss, microcephaly, intellectual deficits or vision abnormalities. In fact, HCMV is the most common non-genetic cause of hearing loss in children worldwide.

 

 

Via multiple PRR, HCMV infection potently induces secretion of type I IFNs, which then induce expression of a specific set of ISGs via the IFNAR. However, (i) how these ISGs affect HCMV replication, (ii) if HCMV developed countermeasures against certain ISGs or (iii) even uses them for its own benefit is poorly understood.

Our project aims to characterize the antiviral or proviral role of selected ISGs induced upon HCMV infection and to demonstrate their mechanism of action in the context of viral infection.

 

 


 

Contact details

Melanie M. Brinkmann, Professor

Viral Immune Modulation Research Group

Helmholtz Centre for Infection Research

Inhoffenstrasse 7

38124 Braunschweig

Germany

 


 

 

ESR13 - Identification of novel immune modulatory mechanisms of human cytomegalovirus

Helmholtz Centre for Infection Research, Braunschweig, Germany

 

Student: Markus Fabits, Ph.D. fellow

Supervisor: Prof. Dr. rer. nat. Melanie Brinkmann

 

 

 

 

Human cytomegalovirus (hCMV) is a common virus that is spread worldwide in the human population. After primary infection, which often occurs without any symptoms, hCMV stays in the body for life in a dormant state and can reactivate under certain circumstances. In people with an intact immune system, hCMV infection is usually well controlled and the human body is protected from illness. However, if the immune system is not working properly, e.g. in immunocompromised organ transplant patients, HIV-infected people or people with genetic deficits, hCMV can cause severe diseases. Moreover, babies that were infected with hCMV by their mother during pregnancy can develop severe complications that are either apparent directly after birth or develop at later stages. Health problems due to congenital CMV infection include organ malformations, vision and hearing loss and developmental delay.

 

 

 

Important sentinels of our immune system are proteins that detect intruders and initiate a potent defense program against them. These proteins are called pattern recognition receptors (PRR) and are present in almost every cell in our body. PRR guard the cell surface and the interior of the cell and recognize either unique patterns of pathogens or perturbations that are induced by the infection. The invaded body cells then secrete signal molecules, called interferons, which further fight the intruders by creating an antiviral state and additionally warn surrounding uninfected cells about an ongoing infection. This first line of defense is deployed by the so-called innate immune system (Figure).

 

 

 

However, hCMV evolved elegant and efficient countermeasures to overcome immune control and ensure lifelong persistence. The aim of this project is to first identify individual hCMV proteins that counteract the early innate immune response mediated by PRR (Figure B). As a second step, we will analyse the role of the identified protein in the context of virus infection. To do so, we will create a mutant virus that lacks the identified PRR modulator and analyse its effect on the IFN response in comparison to wild type hCMV.

 

 

 

With the help of molecular, cell biological and immunological tools we will then study how the identified viral IFN modulator exerts its function. An increasing knowledge of hCMV immune evasion strategies may lead to improved treatment options to prevent infection and subsequent lifelong persistence of hCMV.

 

 

 

 


 

Contact details

Melanie M. Brinkmann, Professor

Viral Immune Modulation Research Group

Helmholtz Centre for Infection Research

Inhoffenstrasse 7

38124 Braunschweig

Germany

 


 

 

ESR12 - Novel primary immunodeficiencies associated with herpes zoster

Aarhus University Hospital, Denmark

 

 

Student: Madalina Carter-Timofte, Ph.D. fellow

Supervisor: Prof. Trine H Mogensen, M.D., Ph.D.

 

Varicella Zoster Virus (VZV) is the causative agent of chicken pox; a childhood disease that infects the majority of the Western population. Interestingly, even after the infection has been cleared, the virus is able to remain hidden in the human host, and can be reactivated to cause herpes zoster or shingles. In very few individuals, infection with VZV can spread to the central nervous system (CNS) and can cause severe complications such as inflammation of the brain, also known as encephalitis. However, why some individuals develop severe neurological complications, whereas most people do not, remains unknown.

Key to an individual’s ability to fight infections is their defence mechanism, also known as the innate immune response. Immune cells are able to recognize foreign infections, and target them for destruction. Our project aims to investigate if individuals who develop severe VZV complications have different genetic variations, known as mutations, particularly in their immune defense mechanism. We predict that these genetic modifications may go some way to explain why some people develop severe disease, whereas others do not'.

 

 


 

Contact:

Trine H Mogensen, Associate professor

Department of Infectious Diseases

Aarhus University Hospital Skejby

Palle Juul-Jensens Boulevard 99

DK-8200 Aarhus N

Denmark

Phone: +4520125280

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ESR11 - Innate immune sensing and restriction of Varicella zoster virus

University of Oxford, UK

 

Student: Jonny Hertzog, Ph.D. fellow

Supervisor: Prof. Jan Rehwinkel, Ph.D.

 

 

 

Varicella-Zoster Virus (VZV), or Human Herpes Virus 3, is an important human pathogen associated with the clinical presentations Varicella (chicken pox) and Zoster (shingles). In the pre-vaccine era, virtually every individual got infected with VZV during childhood presenting as Chicken pox. Primary infection generates life-long immunity against subsequent infections; the same is achieved by the attenuated live virus vaccine. The virus, however, establishes latency in peripheral ganglia. Reactivation due to immunosuppression or declining immune surveillance in older individuals can lead to the occurrence of shingles. The associated morbidity can be severe and irreparable. Furthermore, VZV is part of a group of pathogens that can damage the developing fetus (congenital VZV syndrome). Primary or secondary VZV infections can also lead to life-threatening complications, such as herpes encephalitis.

 

The clinical features of VZV infection are well described, and a vaccine is licensed for the prevention of chicken pox and shingles. The molecular virology and immunology of VZV, however, remain poorly defined. For an organism to be able to mount an immune response against any pathogen, recognition of infection is crucial. In this project, we aim to characterise the innate immune sensors that recognise infection with VZV. We furthermore want to identify viral proteins that modulate and/or antagonise the innate immune response to VZV. By identifying cellular interaction partners of these proteins, we aim to elaborate on their function as cellular restriction factors.

 

Ultimately, this research feeds into a better molecular understanding of herpes virology and the development of more effective antiviral drugs.

 

 

 


 

Contact details

Jan Rehwinkel, Associate Professor of Innate Immunology

MRC Human Immunology Unit

Weatherall Institute of Molecular Medicine

Radcliffe Department of Medicine

University of Oxford, UK

This email address is being protected from spambots. You need JavaScript enabled to view it.

www.imm.ox.ac.uk/jan-rehwinkel