Evaluation of dried blood spots for serological surveys of myxoma and rabbit hemorrhagic disease viruses in their wild reservoir

Myxoma (MYXV) and rabbit hemorrhagic disease (RHDV) viruses are pathogens of economic relevance for cuniculture and conservation concern for wild European rabbits (Oryctolagus cuniculus), recently classified as ‘Endangered’ in its native range. Large-scale serological surveys, facilitated by sample collection using dried blood spots (DBS), allow monitoring seroprevalence in the wild reservoir but require evaluating the technique for the host and pathogen of interest. This study aimed to evaluate Protein Saver 903 DBS for MYXV and RHDV (genotype GI.2) serological surveys in European rabbits. Paired serum and DBS collected from 172 rabbits harvested or found dead in the Iberian Peninsula were tested for IgG antibodies specific against MYXV and RHDV GI.2 using indirect ELISA. We found an almost perfect agreement between serum and DBS for MYXV (Cohen's κ=0.914, CI₉₅ 0.847 – 0.981) and a strong agreement for RHDV GI.2 (Cohen's κ=0.808, CI₉₅=0.722 – 0.893). The diagnostic sensitivity of DBS was 95.4 % (CI₉₅ 90.3 – 97.9 %) for MYXV and 82.1 % (CI₉₅ 73.2 – 88.5 %) for RHDV GI.2. The diagnostic specificity and positive predictive value were 100 % for both pathogens. This study supports DBS as a suitable sampling strategy for serological surveys of antibodies specific to MYXV and RHDV GI.2 in European rabbits, which generally agrees with results from other hosts and pathogens where this technique was evaluated.