Sequential activation of DNA viruses by the RNA virus SARS-CoV-2 in patients with long COVID syndrome

Background: Reactivation of Epstein-Barr virus (EBV) has been suggested to play role in long lasting multiorgan symptoms several months after the initial COVID-19 illness.

Purpose: The aim of our prospective study was to 1) to evaluate the reactivation of DNA viruses of EBV, Cytomegalovirus, Herpes simplex, Varicella zoster and Parvovirus-B19 by SARS-CoV-2 in patients with the diagnosis of long-COVID syndrome, 2) to investigate the effect of supposed virus reactivation on clinical conditions and long COVID syndromes.

Methods: Patients with long COVID syndrome were prospectively included into the Vienna PostCoV Registry between March 15th 2021 and September 30th 2021. – The time between COVID-19 infection and first clinical visit was 219±98 days (7±3 months). Clinical symptoms were documented and patients were divided into symptoms-oriented subgroups with dominantly respiratory, cardiovascular or neuropsychologic complaints. Qualitative and quantitative viral IgG and IgM titer of the selected DNA viruses of n=105 patients were compared with age and sex-matched healthy (non-infected, non-vaccinated, n=105) controls, who had neither spike- nor nucleocapsid antibodies, nor clinical history of COVID-19 disease.

Results: Long Covid patients had significantly higher cumulative number of IgM positivity of the DNA viruses (18.1% vs 6.7%, p=0.02), and significantly elevated quantitative EBV IgG (420±296 vs 339±282 mg/dL, p=0.033) and Parvo-B19 IgM (0.28±0.29 vs 0.03±0.12 mg/dL, p<0.001) titer as compared to healthy controls. Significantly more patients with long COVID symptoms had an EBV IgG titer above the detection limit as compared with healthy controls (40% vs 28%, p=0.018), suggesting EBV virus reactivation and chronic EBV infection. EBV IgG titer was significantly higher in patients with dominant respiratory symptoms, while elevated Parvo-B19 IgM titer was observed in patients with dominant cardiovascular complaints. In patients with long-COVID syndrome the quantitative EBV IgG titer increased with the time between infection and blood sampling (logarithmic correlation, p=0.011), suggesting the subclinical continuous EBV activation by the SARS-CoV2 RNA virus, while the quantitative Parvo-B19 IgM titer decreased linearly during the observation period

Conclusions: In this study of patients with long-COVID syndrome, SARS-CoV-2 infection apparently activated certain types of DNA viruses (EBV, and Parvo-B19), as demonstrated by the significantly higher incidence of cumulative IgM positivity, and elevated EBV IgG and parvovirus-B19 IgM titers, in long-COVID patients compared to healthy controls.