Science Bite (3 minute oral presentation with PPT in live session and poster) - Students, ECRs and EMCRs only 15th Lorne Infection and Immunity 2025

Investigation of microbe associated antibody cross-reactivity in SARS-CoV-2 nucleocapsid immune response (#314)

Joshuah Fialho 1 , Rhiane Moody 1 , Kirsty Wilson 1 , Georgia Goodchild 1 , Cyril Deceneux 1 , Monica Prakash 1 , Sabrina Sonda 2 3 , Fay H Johnston 4 5 , Kylie J Smith 4 5 , Nicola Stephens 6 , Michelle McPherson 6 , James H McMahon 7 8 , Ben Rogers 7 9 , Katie Flanagan 1 2 3 6 , Magdalena Plebanski 1
  1. School of Health and Biomedical Science, STEM College, RMIT university, Bundoora, VIC, Australia
  2. Tasmanian Vaccine Trial Centre, Clifford Craig Foundation, Launceston General Hospital, Launceston, TAS, Australia
  3. School of Health Sciences and School of Medicine, University of Tasmania, Launceston, TAS, Australia
  4. Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
  5. Public Health Services, Department of Health, Tasmania, TAS, Australia
  6. Tasmanian School of Medicine, University of Tasmania, Hobart, TAS, Australia
  7. Monash Infectious Diseases, Monash Health, Clayton, VIC, Australia
  8. Department of Infectious Diseases, Alfred Health and School of Translational Medicine, Monash University, Melbourne, VIC, Australia
  9. Monash University School of Clinical Sciences, Monash Health, Clayton, VIC, Australia

Infection with SARS-CoV-2, the etiological agent of the COVID-19 pandemic, has resulted in more than 7 million deaths to date. The majority of current immunological research focuses on the spike protein owing to its incorporation in major vaccine formulations, while the studies of immune responses to nucleocapsid protein (NP) have been largely limited to serological testing for COVID-19 positivity. A prior study from our lab detected anti-nucleocapsid antibodies in SARS-CoV-2 unexposed health care workers. A possible explanation for this observation could be antibody cross-reactivity mediated by immune exposure to similar epitopes on unrelated microbes. However, the nature and extent of this potential cross-reactivity remains to be delineated. To test this, bioinformatically determined NP B-cell epitopes were run through NCBI BLAST to identify peptides with similar (conserved amino acid residues), as well as identical sequences. Utilizing criteria previously defined to identify these similarities between SARS-CoV-2 and human proteins1, the potential of immune cross-reactivity between SARS-CoV-2 and other microbes was investigated. This resulted in a total of 10 potential microbial cross-reactive (CR) peptides against 4 NP peptides. Interestingly, one such region of NP/ CR similarity was also observed in a human protein, suggesting multiple microbial/COVID-19/autoantigen reactivities could exist. Reactivity to the NP and CR peptides, in terms of anti-IgG responses, was subsequently evaluated via indirect ELISA in a cohort of known COVID-19 exposed vs unexposed, as well as confirmed COVID-19 positive, negative or unknown volunteers (n=295). Simultaneous NP and CR peptide recognition was preferentially observed in COVID-19 exposed individuals. Donors with dual NP and CR peptide reactivities are being further evaluated for overlapping antibody binding (cross-reactivity) between the NP and CR peptides as well as the regions of similarity or identity within these peptides, via competition ELISAs.

  1. Moody, R., Wilson, K. L., Boer, J. C., Holien, J. K., Flanagan, K. L., Jaworowski, A., & Plebanski, M. (2021). Predicted B cell epitopes highlight the potential for COVID-19 to drive self-reactive immunity. Frontiers in Bioinformatics, 1, 709533.