A Field-Applicable Method for Bluetongue Virus Detection Using Filter Paper Cards

Abstract

Simple Summary The diagnosis of Bluetongue Virus (BTV) in Argentina is predominant reliant on RT-qPCR, but it is challenged by the scarcity of diagnostic laboratories and the considerable distances between sampling sites and testing facilities. These logistical constraints underscore the necessity for simple and reliable methods for sample preservation and transport. The objective of this study was to standardize a filter paper-based sampling protocol for BTV molecular diagnosis. Hydration with TE at 37 °C provided optimal analytical performance, yielding ~10 TCID50/mL as the lowest viral concentration consistently detected under the experimental conditions. The sample stability was assessed after storage at temperatures of 25 °C, 4 °C, −20 °C, and −80 °C for up to 360 days. The results demonstrated that diagnostic stability was maintained up to 120 days under all conditions tested. The absence of infectious material in card eluates, substantiates their biosafety with regard to transport and handling. A preliminary field evaluation using blood samples from cattle and sheep showed nearly perfect agreement between card-based and conventional sampling (Cohen’s kappa). This standardized approach offers a practical and safe alternative for BTV surveillance, enabling sample transport without refrigeration while preserving diagnostic performance.