Background: Respiratory viral co-infections influence viral dynamics, disease severity, and mucosal immune responses. Human rhinovirus (HRV), a prevalent respiratory virus that frequently co-circulating with SARS-CoV-2, is known to induce strong inter...
Background: Respiratory viral co-infections influence viral dynamics, disease severity, and mucosal immune responses. Human rhinovirus (HRV), a prevalent respiratory virus that frequently co-circulating with SARS-CoV-2, is known to induce strong interferon (IFN) responses capable of suppressing other respiratory viruses. However, the interaction between HRV and SARS-CoV-2 in human nasal epithelial cells (HNECs) remains incompletely understood, particularly in the context of chronic rhinosinusitis (CRS). CRS without nasal polyps (CRSsNP) and CRS with nasal polyps (CRSwNP) exhibit distinct patterns of inflammation and host antiviral responses that may differentially influence the outcome of viral co-infection.
Methods: We used well-differentiated primary human nasal epithelial cells (HNECs) derived from healthy controls and CRS patients, including CRSsNP and CRSwNP. HNECs were infected with SARS-CoV-2 (Omicron BA.5) and human rhinovirus (HRV16) under single, simultaneous, and sequential infection conditions. Viral RNA levels, expression of viral entry receptors (full-length ACE2 and ICAM-1), and host antiviral responses (IFN-β, IFN-λ1, IFN-λ2, and dACE2) were quantified by RT-qPCR at 0, 2, and 5 days post infection (dpi).
Results: HRV consistently suppressed SARS-CoV-2 under all co-infection conditions, with the strongest inhibition observed when HRV infection preceded SARS-CoV-2. In contrast, SARS-CoV-2 exerted minimal effects on HRV, with only modest reductions observed when it preceded HRV. During simultaneous co-infection, SARS-CoV-2 and HRV RNA levels were positively correlated, suggesting co-regulation by shared epithelial antiviral responses rather than direct viral interference. CRS subtype-specific differences were also evident, with controls generally exhibiting lower SARS-CoV-2 loads than CRS groups, consistent with lower full-length ACE2 and higher IFN-λ1 expression at baseline. CRSsNP showed robust interferon responses across conditions, while non-eosinophilic CRS (non-ECRS) exhibited the highest viral loads of both viruses, along with strong type I and III interferon induction and elevated full-length ACE2 expression following infection.
Conclusion: Our findings highlight that viral interference is not solely determined by intrinsic viral properties, but is also modulated by infection conditions and CRS-associated differences in epithelial immunity, offering new insights into virus-host interactions in the inflamed upper airway.