Poster Presentation 12th Australasian Virology Society Meeting 2024

Comparative analysis of seasonal and pathogenic coronavirus infections in four physiologically relevant models of the human respiratory tract   (#156)

Matthew Gartner 1 , Jessica Neil 1 , Randy Suryadinata 2 , Joseph Chen 3 , Phil Robinson 2 , Jose Polo 3 , Kanta Subbarao 1
  1. Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
  2. Royal Children's Hospital, Parkville, VIC, Australia
  3. Monash University, Clayton, VIC, Australia

Background: 

Seasonal hCoVs (including 229E, NL63 and OC43) cause 15-20% of common colds and are associated with mild illness. In contrast, three hCoVs (SARS-CoV, MERS-CoV and SARS-CoV-2) have emerged in the last 20 years to cause severe respiratory disease. We aimed to compare virus replication kinetics, cellular tropism and host response to seasonal and pathogenic CoVs in four models that represent the full length of the human respiratory tract. 

Methods: 

Human nasal epithelial cells (hNECs), large airway epithelial cell (LAEC) and small airway epithelial cell (SAEC) cultures were differentiated at an air-liquid interface. Human embryonic stem cells were differentiated into alveolar type II (AT2) cells. Cultures were inoculated with seasonal hCoVs (229E and NL63) or pathogenic hCoVs (SARS-CoV-2 or MERS-CoV). Virus growth, cytokine responses and induction of cell death were assessed by infectivity assay, cytokine bead array and LDH assay, respectively. Immunohistochemistry and confocal microscopy were used to determine cellular tropism. 

Results: 

Replication of seasonal hCoVs 229E and NL63 in hNECS, LAECs, SAECs and AT2 cultures was modest in comparison to SARS-CoV-2 and MERS-CoV. SARS-CoV-2 and NL63 infected ciliated cells in hNECS, LAECs and SAECs, while 229E infected ciliated and basal cells. We observed a gradient in cytokine responses, hNECs showed the most robust cytokine response and AT2 cells showed minimal responses. Compared to seasonal hCoVs, SARS-CoV-2 induced strong IFN-β and IFN-λ1 responses in hNECs. 229E showed the greatest LDH release in all four culture systems, despite modest viral replication. Cellular tropism, cytokine response and LDH analysis is ongoing for MERS-CoV.  

Conclusion: 

Seasonal and pathogenic CoVs demonstrate differences in replication kinetics, cellular tropism and host responses in cells derived from different locations of the human respiratory tract. Characterising CoV-host interactions in physiologically relevant models of the human respiratory tract will improve our understanding of disease phenotypes and transmission characteristics.