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Project B6: Hanna Menschikowski, MD student

Construction and Evaluation of murine cytomegalovirus (MCMV) targeting Bispecific T cell enhancer (BiTE®)

The human cytomegalovirus (HCMV) presents one of the major threats regarding allogenic stem cell transplants. It belongs to the Herpes virus family and reflects as an asymptomatic infection in immunocompetent patients. However, if the immune system is compromised due to iatrogenic or intrinsic suppression, the infection might reactivate. It concludes in a broad spectrum of symptoms such as diarrhoea, retinitis and pneumonia, all of which possibly life threatening.

The most at risk proposition is a sero-positive stem cell recipient matched with a sero-negative donor. As HLA-matches are most important to prevent graft-versus-host disease, this is prioritized over CMV sero-status. Under immune suppression and even after, the immune system is not able to battle the infection, therefore medication is needed.

Antiviral drugs like Ganciclovir and HLA-matched ex vivo expanded immune cells are established processes to treat CMV infection. These however either evoke resistance mechanisms or are expensive and time intensive. 

A possible solution is using Bispecific T cell enhancer (BiTE®s). This concept is already benefitting B cell leukaemia therapy (Blinatumomab©), which will also allow HLA-independence. Presuming an immune system is present, T cells are directed to infected cells and then elicit an immune response.

The BiTE is constructed with two single chains. One is directed to CD3 to bind T cells; one binds viral glycoproteins such as gB, gH and gN.

In this project, I will construct several BiTE®s that bind different viral glycoproteins of murine Cytomegalovirus (MCMV) as it is the only established animal model for CMV right now. I will then assess stable transfected and infected Murine Embryonic Fibroblasts (MEF) for BiTE® efficacy, not only regarding cytotoxic T cell response but also cytokine related suppression. This is in the interest of judging CMV’s immune evading mechanisms and how they affect therapeutic success.

If in vitro studies show promising results, we will then move on to test BiTE®s in MCMV-infected immunodeficient RAG-/- mice to determine efficacy, dosage and possibly asses BiTE® combinations by investigating viral organ load and Luciferase expression (with usage of Luciferase expressing virus).