B cell dysregulation during acute COVID-19 is transient

Area of Science:

• Immunology
• Virology
• Infectious Diseases

Background:

• COVID-19 (Coronavirus disease 2019) remains a global health challenge.
• B cell responses in severe COVID-19 are well-documented, but less is known about mild cases or long-term immune changes.
• Herpesvirus reactivation during acute COVID-19 is a potential factor in post-acute sequelae of COVID-19 (PASC).

Purpose of the Study:

• To investigate the natural kinetics of B cell subpopulations during acute COVID-19 and recovery.
• To assess serological markers of B cell activity and herpesvirus reactivation.
• To correlate herpesvirus reactivation with the persistence of anosmia (smell loss) as a proxy for PASC.

Main Methods:

• Collected samples from 120 SARS-CoV-2 positive patients (outpatients and inpatients) up to 460 days post-symptom onset.
• Utilized flow cytometry to analyze B cell and T helper cell subpopulations.
• Measured free light chains, Epstein-Barr virus (EBV) serology, and herpesvirus quantitative PCR (qPCR).
• Assessed anosmia via self-report at 3-12 months post-COVID.

Main Results:

• B cell and T helper cell subpopulation changes normalized within 200 days post-symptom onset.
• Free light chains were elevated in acute COVID-19, particularly in inpatients, but normalized over time.
• Epstein-Barr virus (EBV) and human herpesvirus 6B (HHV-6B) reactivations were significantly more frequent in inpatients (47% and 19%, respectively) compared to outpatients (4.3% and 0%).
• Anosmia was not significantly associated with any observed herpesvirus reactivation.

Conclusions:

• SARS-CoV-2 infection induces transient alterations in circulating B cell and T helper cell populations that resolve during follow-up.
• EBV and HHV-6B reactivations are prevalent in hospitalized COVID-19 patients.
• Herpesvirus reactivation does not appear to be linked to the development of persistent anosmia following COVID-19.