Systemic and local infection routes govern different cellular dissemination pathways during gammaherpesvirus infection in vivo.

Human gammaherpesviruses cause morbidity and mortality associated with infection and transformation of lymphoid and endothelial cells. Knowledge of cell types involved in virus dissemination from primary virus entry to virus latency is fundamental for the understanding of gammaherpesvirus pathogenesis. However, the inability to directly trace cell types with respect to virus dissemination pathways has prevented definitive conclusions regarding the relative contribution of individual cell types.

Shedding light on the elusive role of endothelial cells in cytomegalovirus dissemination.

Cytomegalovirus (CMV) is frequently transmitted by solid organ transplantation and is associated with graft failure. By forming the boundary between circulation and organ parenchyma, endothelial cells (EC) are suited for bidirectional virus spread from and to the transplant. We applied Cre/loxP-mediated green-fluorescence-tagging of EC-derived murine CMV (MCMV) to quantify the role of infected EC in transplantation-associated CMV dissemination in the mouse model.

The role of cell types in cytomegalovirus infection in vivo.

Human cytomegalovirus (HCMV) is the major viral cause of morbidity in immune compromised patients and of pre- and perinatal pathology in newborns. The clinical manifestations are highly variable and the principles which govern these differences cannot be understood without detailed knowledge on tissue specific aspects of HCMV infection. For decades the role of individual cell types during cytomegalovirus infection and disease has been discussed.

A spread-deficient cytomegalovirus for assessment of first-target cells in vaccination.

Human cytomegalovirus (HCMV) is a human pathogen that causes severe disease primarily in the immunocompromised or immunologically immature individual. To date, no vaccine is available. We describe use of a spread-deficient murine CMV (MCMV) as a novel approach for betaherpesvirus vaccination.

Virally infected mouse liver endothelial cells trigger CD8+ T-cell immunity.

Background & Aims: Dendritic cell activation through ligation of pattern recognition receptors leading to full functional maturation causes induction of CD8(+) T-cell immunity through increased delivery of costimulatory signals instead of tolerance. Here we investigate whether organ-resident antigen-presenting cells, such as liver sinusoidal endothelial cells (LSECs), also switch from tolerogenic to immunogenic CD8(+) T-cell activation upon such stimulation.

Methods: Murine LSECs were isolated by immunomagnetic separation and analyzed for functional maturation upon triggering pattern recognition receptors or viral infection employing gene expression analysis and T cell coculture assays.

Tumor agonist peptides break tolerance and elicit effective CTL responses in an inducible mouse model of hepatocellular carcinoma.

Tumors often induce tolerance in the immune system, which may contribute to the limited success of clinical vaccination against tumors. In order to develop strategies for overcoming tumor tolerance we have developed an inducible mouse model of autochthonus hepatocellular carcinoma growth, which relates more closely to the clinical situation than transplantation tumors. These so-called AST mice harbour a construct consisting of the hepatocyte-specific albumin promoter, a loxP flanked stop-cassette, and the oncogene SV40 large T antigen (Tag).

The major virus-producing cell type during murine cytomegalovirus infection, the hepatocyte, is not the source of virus dissemination in the host.

The course of systemic viral infections is determined by the virus productivity of infected cell types and the efficiency of virus dissemination throughout the host. Here, we used a cell-type-specific virus labeling system to quantitatively track virus progeny during murine cytomegalovirus infection. We infected mice that expressed Cre recombinase selectively in vascular endothelial cells or hepatocytes with a murine cytomegalovirus for which Cre-mediated recombination would generate a fluorescently labeled virus.

Conditional gene expression systems to study herpesvirus biology in vivo.

Cytomegalovirus (CMV), a prototypic beta-herpesvirus, is an important human pathogen causing protean clinical manifestations in immature and immunocompromised patients. Mechanisms of infection can be studied in a mouse model. Mouse cytomegalovirus (MCMV) resembles in pathogenesis its human counterpart in many ways.

Natural killer cells promote early CD8 T cell responses against cytomegalovirus.

Understanding the mechanisms that help promote protective immune responses to pathogens is a major challenge in biomedical research and an important goal for the design of innovative therapeutic or vaccination strategies. While natural killer (NK) cells can directly contribute to the control of viral replication, whether, and how, they may help orchestrate global antiviral defense is largely unknown. To address this question, we took advantage of the well-defined molecular interactions involved in the recognition of mouse cytomegalovirus (MCMV) by NK cells.

Engineering of cytomegalovirus genomes for recombinant live herpesvirus vaccines.

The advances of sequence knowledge and genetic engineering hold a great promise for a rational approach to vaccine development. Herpesviruses are important pathogens of all vertebrates. They cause acute and chronic infections and persist in their hosts for life.

Conditional cytomegalovirus replication in vitro and in vivo.

We have established a conditional gene expression system for cytomegalovirus which allows regulation of genes independently from the viral replication program. Due to the combination of all elements required for regulated expression in the same viral genome, conditional viruses can be studied in different cell lines in vitro and in the natural host in vivo. The combination of a self-sufficient tetracycline-regulated expression cassette and Flp recombinase-mediated insertion into the viral genome allowed fast construction of recombinant murine cytomegaloviruses carrying different conditional genes.

CpG-ODN-induced inflammation is sufficient to cause T-cell-mediated autoaggression against hepatocytes.

Autoimmune diseases are often associated with microbial infections. Molecular mimicry between microbial antigens and self-epitopes has been suggested as a mechanism for breaking self-tolerance and induction of autoimmunity. Since infections also cause inflammatory responses we explored the role of local inflammation in organ-specific autoimmunity.