Research Group EBV Genetics and Vectors

Projects

We are working on several topics and themes that, to us, appear attractive and worth pursuing. Our interest is fed by our curiosity and driven by our hopes of discovering previously unknown processes, strategies and tricks EBV plays on the cells it infects.

Epigenetic regulation of EBV’s life cycle

The situation: When EBV infects a human cell, the viral DNA is epigenetically naïve, i.e. it lacks nucleosomes, is free of histone proteins and does not contain 5’-methylcytosine residues. The outcome of EBV infecting any cell is nonproductive and a latent infection ensues. Later, upon chromatinization of the viral genomic DNA and incorporation of 5’-methylcytosines the latently infected cells can support EBV’s lytic phase.

The questions: How does the epigenetically naïve EBV DNA acquire its characteristic epigenetic signature? What are the factors involved in chromatinization? Is chromatinization essential to establish a latent infection?

The perspective: Knowing the crucial steps in chromatinization is a prerequisite to consider means and measures that can prevent viral infection and abrogate the co-existence of the virus and its host cell.

BZLF1 and its peculiar characteristics

The situation:  BZLF1 is EBV’s molecular switch protein that induces the virus’s lytic phase in latently infected cells. How this protein exerts this critical function is not fully understood, but its expression activates a cascade of viral genes that are essential during EBV’s lytic phase supporting de novo virus synthesis.

The questions: We shall analyze how the BZLF1 protein executes its function as a pioneer transcription factor. It must gain access to epigenetically repressed viral chromatin to activate transcription of many silenced viral genes. How does it do this? Are additional proteins (cellular and/or viral) involved in this key process? How does its binding to viral DNA recruit the cellular transcription machinery? How does it induce transcription? Do cellular proteins exist that share properties with BZLF1 and regulate cellular genes?

The perspective: We hope to decipher this fundamental step and learn how to put it to use fighting EBV-associated diseases.

Immediate steps and processes following infection with EBV

The situation: When EBV infects a human B cell, a number of viral genes are initially expressed. Surprisingly, not all of them belong to the typical set of latent viral genes. We proposed to call this initial stage the pre-latent phase of EBV, which precedes the classical latent phase of EBV’s life cycle. We have only a vague idea how the set of viral genes expressed in the pre-latent phase influence the fate of the infected cell.
 
The questions: Our picture is likely incomplete. We wish to know which viral genes are expressed during the pre-latent phase. We know of several viral genes that are essential for establishing a latent infection in human primary B cells but do we know them all? What are the function(s) and task(s) of the early viral genes?

The perspective: Knowing the viral gene expressed in the pre-latent phase is critical to understand how EBV usurps its host cell. We wish to identify the cellular processes the virus must control to establish a latent infection and reprogram its cellular host. Only then can we build new hypothesis to interfere with the virus’s strategy (and success) in the pre-latent phase.

EBV’s micro RNAs and their functions

The situation: One class of viral gene products are micro RNAs (miRNAs) that are expressed in the pre-latent phase as well as in latently infected cells. So far, we know little about the functions of these miRNAs.

The questions: What are the effects of viral miRNAs in newly and latently infected cells? Which (cellular) circuits and networks does the virus control and modulate via its miRNAs that likely interfere with the translation of cellular transcripts?  

The perspective: miRNAs are promising targets for novel biomedicals that have therapeutic potential. Targeting viral miRNAs is particularly attractive because they are present in infected cells, only. It would be interesting to develop therapeutic approaches against EBV’s miRNAs if we knew what their functions are.

Overcoming the hurdle of EBV production

The problem:  Unfortunately, we lack a cell that immediately gives rise to progeny virus upon viral infection. Infecting cells latently is a hallmark of EBV’s biology but an obstacle to generate viral mutants that can be phenotypically analyzed, for example.

The questions: How can we devise molecular cues to overcome this obstacle? Will it be possible to bypass this aspect of EBV’s smart biology by engineering cells that support de novo virus synthesis upon infection with EBV?

The perspective: We hope to solve this central issue in order to generate virus stocks that might be suitable as EBV vaccines in the future.

Thoughts about gene vectors

The problem: Viruses can do harm to infected cells and the organism but they are also suitable vectors to efficiently deliver genes of interest. Viruses or engineered gene vectors can thus provide new functions to infected or transduced cells, respectively. 



The questions: What is the ideal gene vector in order to transduce human primary B cells selectively? Can EBV-based vectors deliver therapeutic genes to malignant B cells? Can gene vectors be used to provide resistance to subsequent viral infections?



The perspective: Gene vectors hold promise to solve biomedical problems that appear unsurmountable today. Putting safe gene vectors to use is a task that cannot be reached in a single step because ethical problems ensue and technical obstacles remain. We emphasize on improving EBV gene vectors that can be delivered to human B cells or act at the level of a single cell to provide resistance to herpesviral infections.

Our work is supported by institutional funds provided by the Helmholtz Zentrum München and the Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF), grants from the Deutsche Forschungsgemeinschaft (DFG), Deutsche Krebshilfe and other foundations.

We participate in Collaborative Research Centers of the Deutsche Forschungsgemeinschaft: SFB TR5, SFB TR36, SFB 1054 (pending).

We are a member of the DZIF, German Centre for Infection Research, Munich.