Toscana Virus Diagnosis via a Point-of-Care Tool Based on Disposable Optical Fiber Biosensors

The Toscana virus (TOSV) is an emerging Phlebovirus endemic to the Mediterranean region, with marked neurotropism, responsible for often undiagnosed cases of meningitis and meningoencephalitis. Rapid and precise identification is critical for medical treatment, but traditional approaches like Polymerase Chain Reaction (PCR) and serology have limits in terms of time, cost, and potential cross-reactivity. This proof-of-concept introduces a low-cost point-of-care test (POCT) based on surface plasmon resonance (SPR) in plastic optical fibers (POFs) combined with an antibody selective for TOSV nucleoprotein. The POF biosensors were tested with serial dilutions of TOSV viral culture in phosphate-buffered solution (PBS), obtaining a detection limit of 0.78 PFU/mL and a highly reproducible dose-response curve. Reliable selectivity was demonstrated in testing with different viruses, including the measles virus, the herpes simplex type 1 virus, and the sandfly fever Naples virus. The POCT capability to measure viral titers was validated by evaluating clinical cerebrospinal fluid samples from infected patients together with PCR. The obtained results were consistent with PCR, suggesting approximately 3 orders of magnitude higher analytical sensitivity and demonstrating its potential as a useful POCT for improving TOSV infection surveillance and clinical management.