Highly specific serological diagnosis of Borna disease virus 1 (BoDV-1) and variegated squirrel bornavirus 1 (VSBV-1) encephalitis by novel antibody isotype assay with multiple viral antigens

Bornavirus encephalitis is a critical and deadly emerging disease in humans in Germany, caused by Borna disease virus 1 (BoDV-1) and variegated squirrel bornavirus 1 (VSBV-1). The disease typically progresses rapidly, but diagnostic efforts, particularly serological tests, are constrained by issues with sensitivity and specificity, often leading to delayed care. This study aimed to create and evaluate a novel spot immunoassay capable of detecting IgG, IgM and IgA antibodies that target four recombinant BoDV-1 proteins: nucleoprotein (N), phosphoprotein (P), accessory protein X (X), and glycoprotein (GP). The study conducted a retrospective analysis on a substantial cohort compromising 15 patients with confirmed bornavirus encephalitis. These were analyzed together with samples from 241 patients suffering from encephalitis of unknown origin, 58 interference samples, and 40 healthy blood donors. The assay demonstrated a highly specific diagnosis (97-100%) for both forms of bornavirus encephalitis. The method also achieved a diagnostic sensitivity of up to 92%. The newly developed spot immunoassay offers a user-friendly, specific, and sensitive tool for the serological diagnosis of human bornavirus encephalitis.
(MKO)