Cell surface nucleocapsid protein expression: A betacoronavirus immunomodulatory strategy

What is it about?

We reported that SARS-CoV-2 Nucleocapsid (N) protein is abundantly expressed on the surface of both infected and neighboring uninfected cells, where it is a target for antibody-based immunity and inhibits leukocyte chemotaxis by binding chemokines. We extend these findings to N from the common cold human coronavirus (HCoV)-OC43, which is also robustly expressed on the surface of infected and non-infected cells by binding heparan-sulfate/heparin. This protein also inhibits CXCL12β-mediated leukocyte migration in chemotaxis assays, as do all highly pathogenic and common cold HCoV N proteins.

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Photo by National Cancer Institute on Unsplash

Photo by National Cancer Institute on Unsplash

Why is it important?

Despite the unprecedented global response to the COVID-19 pandemic, critical aspects of HCoVs pathogenesis remain unclear, including mechanisms underlying immune evasion and viral manipulation of the cytokine network. The N protein is the most abundant HCoV translation product, inducing strong antibody and T-cell responses. Our findings indicate that cell surface HCoV N plays important evolutionary conserved roles in manipulating host innate immunity and as a target for adaptive immunity, beyond sequence and structural divergence. The strong immunogenicity of N and its antigenic stability makes it an attractive target for future HCoV vaccines.

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