A New Human DSG2-Transgenic Mouse Model for Studying the Tropism and Pathology of Human Adenoviruses

Abstract

fWe have recently reported that a group of human adenoviruses (HAdVs) uses desmoglein 2 (DSG2) as a receptor for infection. Among these are the widely distributed serotypes HAdV-B3 and HAdV-B7, as well as a newly emerged strain derived from HAdV-B14. These serotypes do not infect rodent cells and could not up until now be studied in small-animal models. We therefore generated transgenic mice containing the human DSG2 locus. These mice expressed human DSG2 (hDSG2) at a level and in a pattern similar to those found for humans and nonhuman primates. As an initial application of hDSG2-transgenic mice, we used a green fluorescent protein (GFP)-expressing HAdV-B3 vector (Ad3-GFP) and studied GFP transgene expression by quantitative reverse transcription-PCR (qRT-PCR) and immunohistochemistry subsequent to intranasal and intravenous virus application. After intranasal application, we found efficient transduction of bronchial and alveolar epithelial cells in hDSG2-transgenic mice. Intravenous Ad3-GFP injection into hDSG2-transgenic mice resulted in hDSG2-dependent transduction of epithelial cells in the intestinal and colon mucosa. Our findings give an explanation for clinical symptoms associated with infection by DSG2-interacting HAdVs and provide a rationale for using Ad3-derived vectors in gene therapy. Human adenoviruses (HAdVs) have been classified into six species (HAdV-A to HAdV-F) currently containing 55 serotypes. Most adenovirus (Ad) serotypes utilize the coxsackie-adenovirus receptor (CAR) as a primary attachment receptor. However, this is not the case for species B Ad serotypes. Species B Ads form two genetic clusters, B1 (HAdV-B3, -B7, -B16, -B21, and -B50) and B2 (HAdV-B11p, -B14, -B34, and -B35) (84). Recently, we have suggested a new grouping of species B Ads based on their receptor usage (82). The members of group 1 (HAdV-B16, -B21, -B35, -B50) nearly exclusively utilize CD46 as a receptor; the members of group 2 (HAdV-B3, -B7, -B14) use a receptor that was unknown until recently (receptor X), group 3 (HAdV-B11p) preferentially interacts with CD46 but also utilizes receptor X if CD46 is blocked or absent. This novel receptor usage-based grouping system has been supported by studies from various groups (27,50,65,66). A newly emerged, pathogenic strain, Ad14-p1, uses the same receptor as prototype HAdV-B14 (89).HAdV-B3 and -B7 are considered to be widely distributed human pathogens (14,52,59). Studies from the United States show that HAdV-B3 and -B7 infections occur more often in adolescents and adults (23, 92), while studies from Europe and Asia indicate that these serotypes are also common in children (32,45,90). Since 2005, several outbreaks of HAdV-B14p1 in military facilities and civic communities have been reported in various countries, including the United States, Europe, and Asia (8,48,78). Ads, including HAdV-B3, enter the body via the mouth/nose and generally cause respiratory diseases. The respiratory tract epithelium is also the preferred site of viral replication. Subsequent virusinduced cyto...

Intracellular Signaling and Desmoglein 2 Shedding Triggered by Human Adenoviruses Ad3, Ad14, and Ad14P1

“…However, in contrast to human cells, mouse cells do not support productive adenovirus replication. Notably, human adenoviruses do not interact with the mouse orthologue for DSG2 (52). Our study did not reveal significant differences in blood parameters between the two viruses in blood cell counts (Fig.…”

“…In an attempt to study potential pathological effects of Ad14 and Ad14P1, we injected these viruses intravenously into human DSG2-transgenic mice. These mice express human DSG2 in a pattern similar to that of humans, and binding of JO1 to DSG2 on mouse tumor cells that ectopically express human DSG2 triggers junction opening (52). The latter observation indicates that intracellular signaling in DSG2-transgenic mouse cells is similar to that in human cells.…”

“…We found in sera from humans, human DSG2-transgenic mice, and macaques shed DSG2 ECD in the range of several hundred nanograms per milliliter (3,36,52). We also de- tected DSG2 ECD in the supernatant of cultured epithelial cancer cells and in the serum of mice with xenografts derived from human tumor cells (Fig.…”

“…Our previous work has established that binding of Ad3 to DSG2 results in opening of epithelial junctions (3,34,35,52). This process is further enhanced by the production of PtDd during Ad3 infection (30).…”

Structural and Functional Studies on the Interaction of Adenovirus Fiber Knobs and Desmoglein 2

“…This specific mode of Ad3 fiber knob-DSG2 interaction provides a high avidity and is functionally relevant for opening of epithelial junctions (1,2). The latter involves clustering of DSG2 and activation of pathways that are reminiscent of an epithelial-to-mesenchymal transition, including the phosphorylation of mitogen-activated protein kinase (MAPK) and the downregulation of junction protein expression (1,3,4). The ability to open epithelial junctions appears to be important for Ad3 penetration into and spread within airway epithelial cells (1,2,4).…”