Course of HEV viremia and anti-HEV IgM/IgG response in asymptomatic blood donors

Abstract

BackgroundGlobally, an estimated 20 million Hepatitis E infections occur every year. The course of viremia and antibody response has been investigated in patients with symptomatic hepatitis E. However, the majority of HEV infections in industrialized countries take a subclinical course. ObjectivesTo investigate the course of HEV viremia and epitope specific anti-HEV IgM/IgG response in asymptomatic blood donors in order to understand the immune response and viral clearance in asymptomatic blood donors with HEV infections. MethodsIn this study 27 HEV viremic donors were identified by HEV-PCR during routine screening of blood donors and the course of anti-HEV IgM/IgG and HEV-RNA was retrospectively studied using RT-PCR and a commercial immunoblot (Mikrogen®) allowing classification of the antibody response according to HEV epitopes. ResultsAt time of donation, serological testing failed to identify viremic donors as 70.4% had no detectable antibody response. Anti-HEV IgM could be detected in 22.2% of viremic donors while anti-HEV IgG could be found in 7.4%. At least three donors experienced prolonged viremia beyond 100 days. Spontaneous HEV-RNA clearance within a median time span of 57 days was observed in all 27 donors. In all donors anti-HEV IgG specific for the immunogenic viral epitope O2C could be detected in close temporal association with viral clearance. ConclusionSerological testing is inappropriate for identifying HEV-viremic blood donors. Acute HEV infection in asymptomatic blood donors can persist for more than 100 days. HEV-RNA clearance coincided with the appearance of anti-HEV IgM/IgG confirming the importance of a B-cell mediated response in clearing acute infections. Anti-HEV IgM and IgG specific for the epitope O2C are associated with the clearance of HEV-viremia.