Christian Sinzger

Bio: Christian Sinzger is an academic researcher from University of Ulm. The author has contributed to research in topics: Human cytomegalovirus & Virus. The author has an hindex of 37, co-authored 98 publications receiving 7091 citations. Previous affiliations of Christian Sinzger include University of Tübingen.

Genetic content of wild-type human cytomegalovirus

Abstract: The genetic content of wild-type human cytomegalovirus was investigated by sequencing the 235 645 bp genome of a low passage strain (Merlin). Substantial regions of the genome (genes RL1–UL11, UL105–UL112 and UL120–UL150) were also sequenced in several other strains, including two that had not been passaged in cell culture. Comparative analyses, which employed the published genome sequence of a high passage strain (AD169), indicated that Merlin accurately reflects the wild-type complement of 165 genes, containing no obvious mutations other than a single nucleotide substitution that truncates gene UL128. A sizeable subset of genes exhibits unusually high variation between strains, and comprises many, but not all, of those that encode proteins known or predicted to be secreted or membrane-associated. In contrast to unpassaged strains, all of the passaged strains analysed have visibly disabling mutations in one or both of two groups of genes that may influence cell tropism. One comprises UL128, UL130 and UL131A, which putatively encode secreted proteins, and the other contains RL5A, RL13 and UL9, which are members of the RL11 glycoprotein gene family. The case in support of a lack of protein-coding potential in the region between UL105 and UL111A was also strengthened.

Fibroblasts, epithelial-cells, endothelial-cells and smooth-muscle cells are major targets of human cytomegalovirus-infection in lung and gastrointestinal tissues

Abstract: High titre replication of human cytomegalovirus (HCMV) in cell culture is restricted to primary human fibroblasts. During acute infection in vivo, HCMV nucleic acids and antigens have been found in various organs. Using only morphological criteria, inconsistent data have been reported about the cell types that can be infected by HCMV. In particular, the role of fibroblasts in organ infections has remained unclear. To define accurately the target cells of HCMV in vivo, tissue sections from lung and gastrointestinal tract of patients suffering from acute HCMV infection were investigated using immunohistochemical double-labelling analyses. Monoclonal antibodies with defined specificity against immediate early (IE), early (E) and late (L) viral antigens and antibodies directed against cell marker proteins were employed to identify infected cells. The results demonstrated that a broad spectrum of cells was infected by HCMV in vivo. Consistent with their susceptibility in culture, fibroblasts formed a major population of HCMV-infected cells. In contrast, haemopoietic cells were only infrequently stained with virus-specific antibodies. Fibroblasts, epithelial cells, endothelial cells, smooth muscle cells and macrophages appeared to be permissive for HCMV replication. Contrary to this, polymorphonuclear cells showed only IE gene expression, indicating that these cells were abortively infected. The analysis of the distribution of infected cells in tissue supported the hypothesis that endothelial cells and monocytes/macrophages may play a crucial role in the haematogenous spread of HCMV; in contrast, fibroblasts, smooth muscle cells and epithelial cells may form the cell populations important for the multiplication and spread of the virus in infected tissues.

Cytomegalovirus cell tropism.

Abstract: The human cytomegalovirus (HCMV) can infect a remarkably broad cell range within its host, including parenchymal cells and connective tissue cells of virtually any organ and various hematopoietic cell types. Epithelial cells, endothelial cells, fibroblasts and smooth muscle cells are the predominant targets for virus replication. The pathogenesis of acute HCMV infections is greatly influenced by this broad target cell range. Infection of epithelial cells presumably contributes to inter-host transmission. Infection of endothelial cells and hematopoietic cells facilitates systemic spread within the host. Infection of ubiquitous cell types such as fibroblasts and smooth muscle cells provides the platform for efficient proliferation of the virus. The tropism for endothelial cells, macrophages and dendritic cells varies greatly among different HCMV strains, mostly dependent on alterations within the UL128-131 gene locus. In line with the classification of the respective proteins as structural components of the viral envelope, interstrain differences concerning the infectivity in endothelial cells and macrophages are regulated on the level of viral entry.

Cloning and sequencing of a highly productive, endotheliotropic virus strain derived from human cytomegalovirus TB40/E.

Abstract: Human cytomegalovirus (HCMV) strain TB40/E, replicates efficiently, exhibits a broad cell tropism and is widely used for infection of endothelial cells and monocyte-derived cells yet has not been available in a phenotypically homogeneous form compatible with genetic analysis. To overcome this problem, we cloned the TB40/E strain into a bacterial artificial chromosome (BAC) vector. Both highly endotheliotropic and poorly endotheliotropic virus clones, representing three distinct restriction fragment patterns, were reconstituted after transfection of BAC clones derived from previously plaque-purified strain TB40/E. For one of the highly endotheliotropic clones, TB40-BAC4, we provide the genome sequence. Two BACs with identical restriction fragment patterns but different cell tropism were further analysed in the UL128-UL131A gene region. Sequence analysis revealed one coding-relevant adenine insertion at position 332 of UL128 in the BAC of the poorly endotheliotropic virus, which caused a frameshift in the C-terminal part of the coding sequence. Removal of this insertion by markerless mutagenesis restored the highly endotheliotropic phenotype, indicating that the loss of endothelial cell tropism was caused by this insertion. In conclusion, HCMV strain TB40/E, which combines the high endothelial cell tropism of a clinical isolate with the high titre growth of a cell culture adapted strain, is now available as a BAC clone suitable for genetic engineering. The results also suggest BAC cloning as a suitable method for selection of genetically defined virus clones.

Nk cell recognition

Abstract: The integrated processing of signals transduced by activating and inhibitory cell surface receptors regulates NK cell effector functions. Here, I review the structure, function, and ligand specificity of the receptors responsible for NK cell recognition.

The Third International Consensus Guidelines on the Management of Cytomegalovirus in Solid-organ Transplantation

Abstract: Cytomegalovirus (CMV) remains one of the most common infections after solid organ transplantation, resulting in significant morbidity, graft loss, and occasional mortality. Management of CMV varies considerably among transplant centers. A panel of experts on CMV and solid organ transplant was convened by The Infectious Diseases Section of The Transplantation Society to develop evidence and expert opinion-based consensus guidelines on CMV management including diagnostics, immunology, prevention, treatment, drug resistance, and pediatric issues.

Roles of the NKG2D immunoreceptor and its ligands

Abstract: According to present concepts, innate immunity is regulated by receptors that determine danger levels by responding to molecules that are associated with infection or cellular distress. NKG2D is, perhaps, the best characterized receptor that is associated with responses to cellular distress, defined as transformation, infection or cell stress. This review summarizes recent findings that concern NKG2D, its ligands, its signalling properties and its role in disease, and provides a framework for considering how the induction of immune responses can be regulated by cellular responses to injury.

Broadly targeted human cytomegalovirus-specific CD4+ and CD8+ T cells dominate the memory compartments of exposed subjects

Abstract: Human cytomegalovirus (HCMV) infections of immunocompetent hosts are characterized by a dynamic, life-long interaction in which host immune responses, particularly of T cells, restrain viral replication and prevent disease but do not eliminate the virus or preclude transmission. Because HCMV is among the largest and most complex of known viruses, the T cell resources committed to maintaining this balance have never been characterized completely. Here, using cytokine flow cytometry and 13,687 overlapping 15mer peptides comprising 213 HCMV open reading frames (ORFs), we found that 151 HCMV ORFs were immunogenic for CD4 + and/or CD8 + T cells, and that ORF immunogenicity was influenced only modestly by ORF expression kinetics and function. We further documented that total HCMV-specific T cell responses in seropositive subjects were enormous, comprising on average ∼10% of both the CD4 + and CD8 + memory compartments in blood, whereas cross-reactive recognition of HCMV proteins in seronegative individuals was limited to CD8 + T cells and was rare. These data provide the first glimpse of the total human T cell response to a complex infectious agent and will provide insight into the rules governing immunodominance and cross-reactivity in complex viral infections of humans.