Evaluation of an ELISA using recombinant Ssλ20ΔB3 antigen for the serological diagnosis of Sarcoptes scabiei infestation in domestic and wild rabbits.
An ELISA, based on the Sarcoptes scabiei Ssλ20ΔB3 inmunodominant antigen, was evaluated for the detection of antibodies to S. scabiei in experimentally infested (n=10), farm (n=109), and wild (n=78) rabbit sera. The S. scabiei antigen Ssλ20ΔB3, a major structural protein present over the entire mite's body, was produced as a recombinant protein in Escherichia coli and purified for its use in the ELISA. The resulting ELISA showed, in experimentally infested domestic rabbits, detectable specific antibody responses (IgG) above the cut off level from week three post-infestation indicating that the assay is able to detect positive rabbits very early during the course of the infestation. The ELISA was validated on a panel of 109 domestic breeding rabbit sera collected from 26 Spanish farms, of which 41 were obtained from rabbits with skin lesions compatible with sarcoptic mange, 26 with skin lesions compatible with psoroptic mange, and 42 from unexposed individuals from mange-free farms. The ELISA in this group was characterized by 95% sensitivity, 97% specificity, and a high degree of repeatability. In the psoroptic mange compatible lesions group, included in the study as control group for cross-reactivity with the closely related mite Psoroptes cuniculi, cross-reacting antibodies to Ssλ20ΔB3 S. scabiei antigen were detected in 42.30% of the rabbit sera. However, mean% OD values of the sarcoptic-mange group (55.61 ± 39.20%) were significantly higher (p<0.001) than OD values of the psoroptic-mange (3.64% ± 5.4%) and also of the free-mange (0.21% ± 0.67%) groups. In addition, the ELISA was also evaluated in serum samples obtained from both naturally infested and non-infested wild rabbits from Mallorca Island. The sensitivity of the assay for this group was 100% (4 out of the 4 rabbits with sarcoptic mange compatible lesions and presence of S. scabiei mites were seropositive) and the specificity was 90% (67 out of 74 wild rabbits without detectable mange lesions were seronegative). Although, the total number of tested samples from experimentally infested, farm and wild rabbits was limited, our study showed that the ELISA is able to differentiate between infested and non-infested animals in all tested groups with very high sensitivity and specificity indicating that recombinant Ssλ20ΔB3 is a reliable diagnostic antigen. This assay might be a cost-effective tool for detecting the presence of mangy animals and therefore helping prevent spread of mange among domestic rabbits, reducing potential transmission from female breeding rabbits to other farms, and detecting infestation with sarcoptic mange in the wild.
Servicio Regional de Investigación y Desarrollo Agroalimentario (SERIDA), Centro de Biotecnología Animal, La Olla-Deva, 33394 Asturias, Spain. Electronic address: rosacg@serida.org.
Rosa
R
Casais
Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, República 252, Santiago, Chile.
Javier
J
Millán
Cunivet Service, P.O. Box 518, 43080 Tarragona, Spain.
Joan Maria
JM
Rosell
Instituto Universitario de Biotecnología de Asturias, Departamento de Bioquímica y Biología Molecular, Edificio Santiago Gascón, Campus El Cristo, Universidad de Oviedo, 33006 Oviedo, Spain.
Kevin P
KP
Dalton
Servicio Regional de Investigación y Desarrollo Agroalimentario (SERIDA), Centro de Biotecnología Animal, La Olla-Deva, 33394 Asturias, Spain.
José Miguel
JM
Prieto
D000818:Animals; D000829:Animals, Domestic / Q000469:parasitology; D000835:Animals, Wild / Q000469:parasitology; D000906:Antibodies / Q000097:blood; D000941:Antigens / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards / Q000662:veterinary*; D011817:Rabbits; D011994:Recombinant Proteins / Q000276:immunology; D012520:Sarcoptes scabiei / Q000276:immunology*; D012532:Scabies / Q000097:blood / Q000175:diagnosis / Q000662:veterinary*; D012680:Sensitivity and Specificity; D013030:Spain
D000906:Antibodies; D000941:Antigens; D011994:Recombinant Proteins
ELISA; Rabbit; Recombinant antigen Ssλ20ΔB3; Sarcoptes scabiei