Ex Vivo Modeling of Human Cytomegalovirus Infection and
Mucosal Tissue Response at the Nasal Entry Site

Human cytomegalovirus (HCMV) is a leading cause of congenital infection and a major pathogen in immunocompromised individuals. Horizontal HCMV transmission is known to occur following close contact with virus-shedding bodily excretions, yet the initial events of infection at the viral mucosal entry site, which could be an important intervention target, have remained ill defined. HCMV is a human specific virus, precluding animal modeling of early HCMV infection. While it has been assumed that HCMV enters new hosts via the oral route, combined epidemiological and murine-CMV experimental evidence suggest that HCMV infection may be initiated via the nasal route. Here we employed a novel human nasal turbinate organ culture for the ex vivo modeling of HCMV entry via the nasal mucosa. Fresh nasal turbinate tissues were maintained as multi-cell-type organ cultures, and their viability was shown to be preserved for at least 7 days. Active viral replication and spread were observed following ex vivo infection of the nasal turbinate tissues. HCMV primarily infected nasal epithelial cells, along with stromal cells, endothelial cells, and macrophages, exploiting a predominant cell-to-cell mode of spread within the nasal turbinate tissues. Employing a global transcriptome analysis, we further demonstrated a distinct innate immune response of the nasal turbinate tissues to HCMV infection. The ex vivo infected turbinate model provides a unique insight into patterns of infection and innate tissue response during HCMV mucosal-site entry into the human host, and could further serve to evaluate the effects of new intervention strategies against the horizontal transmission of HCMV.