Serosurvey for Antibodies to Bourbon Virus and Related Thogotoviruses in Immunoglobulin Lots Obtained From Human Plasma Collected in the United States and Europe.

This study aimed to investigate the potentially underappreciated circulation of Bourbon virus (BRBV) and related Thogotoviruses by analyzing neutralizing antibodies in US and EU human plasma derived immunoglobulin (IG) lots. Using live virus neutralization assays on 71 IG lots manufactured 2006 to 2024, we quantified BRBV, Thogotovirus (THOV), and Dhorivirus (DHOV) neutralization. THOV and DHOV-antibodies were undetectable in all lots, while BRBV neutralizing titers in US IG showed a borderline significant increase over time; EU IG was largely non reactive. These findings suggest wider than recognized BRBV circulation in the US and support IG based sero-epidemiology as sensitive tool for detecting evidence of past infection by emerging viruses.