Epstein Barr viral shedding dynamics in saliva during acute SARS-CoV-2 infection

Epstein-Barr virus (EBV) establishes latency in most adults and can be reactivated under conditions of co-infection and immune dysregulation. COVID-19 has been associated with EBV reactivation, primarily in hospitalized cohorts, but EBV shedding in the oral cavity and the extent to which these dynamics trigger a systemic anti-EBV antibody response during acute COVID-19 remain poorly understood.

We conducted a nested cohort study of 69 community-based participants including 56 SARS-CoV-2-positive individuals and 13 uninfected household contacts, enrolled as part of a prospective cohort within 5 days of COVID-19 symptom onset. Participants self-collected saliva and nasal samples daily through day 14, then every 3 days until day 21, and once more at day 28. Blood samples were collected on day 28. SARS-CoV-2 RNA in the saliva and nares and EBV DNA in the saliva were quantified by RT-qPCR and qPCR, respectively. EBV antibody responses against viral capsid antigen IgM and IgG, early (D) antigen IgG, and nuclear antigen IgG were quantified in serum by ELISA.

SARS-CoV-2-positive participants tended to be more likely to experience consecutive days of EBV shedding in saliva (p = 0.10) and contributed a higher mean number of EBV DNA-positive specimens compared with uninfected controls (5 vs. 1 per participant in EBV+ participants; p = 0.018). Among SARS-CoV-2-positive participants with EBV reactivation, a positive correlation was observed between maximum EBV DNA in saliva and SARS-CoV-2 RNA levels in saliva (r = 0.49, p = 0.047) but not with SARS-CoV-2 RNA levels in nasal samples (r = -0.12, p = 0.67). EBV reactivation in saliva was not associated with induction of serological responses to systemic EBV reactivation.

This cohort study provides evidence that SARS-CoV-2 infection is associated with prolonged salivary EBV shedding, that concurrent high levels of EBV and SARS-CoV-2 in saliva are correlated, but these salivary EBV shedding dynamics do not drive systemic EBV antibody responses. Further research with larger cohorts and mechanistic assays would be helpful to elucidate the biological pathway triggering systemic EBV antibody responses.