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Updated: May 28, 2025
Author Spotlight: Advancing Antiviral Strategies Through Novel Immunocapture and Mass Spectrometry Techniques
Published on: January 12, 2024
Characterising the SARS-CoV-2 nucleocapsid (N) protein antibody response
C C A Noble1, E McDonald2, S Nicholson3
1Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia; Infectious Diseases Group, Murdoch Children's Research Institute, Parkville, Victoria, Australia.
Objectives:
SARS-CoV-2 nucleocapsid (N) protein antibodies can be used to identify the serological response to natural infection in those who have previously received a COVID-19 spike-based vaccine. Anti-N antibody responses can also be induced by inactivated whole SARS-CoV-2 virus vaccines, such as CoronaVac. We aimed to characterise antibody responses to the N protein following COVID-19 and following vaccination with CoronaVac.
Methods:
Using participants from an international randomised controlled trial, we investigated the evolution of anti-N antibody responses over time in two separate groups: adults following COVID-19, and in adults following vaccination with CoronaVac.
Results:
In 212 participants who had COVID-19, the anti-N seroconversion rate was 96.9% in those infected following an incomplete course of COVID-19 (spike-based) vaccinations and 88.2% in those infected following a complete course. Anti-N antibody indices were highly variable between participants, and higher in participants who had more severe COVID-19 symptoms, were aged ≥60 years, were unvaccinated, had comorbidities and those resident in Brazil. Most participants remained seropositive after 12 months. In 317 separate participants, the anti-N seroconversion rate was 63.5% following CoronaVac vaccination, with variable antibody indices.
Conclusions:
Anti-N responses to COVID-19 and CoronaVac are highly variable but persistent. A prior complete course of COVID-19 spike-based vaccination reduced both anti-N seroconversion and antibody indices following COVID-19.
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