title: Development and evaluation of an indirect enzyme-linked immunosorbent assay for serological detection of Schmallenberg virus antibodies in ruminants using whole virus antigen.
abstract: BACKGROUND
  In late 2011, a new Orthobunyavirus of the Simbu serogroup named Schmallenberg virus (SBV) emerged in continental Europe. The virus is transmitted by hematophagous arthropods, with the Culicoides species as, so far known, main vectors. Infection with the virus can cause clinical signs in adult ruminants including diarrhea, fever and reduced milk production. Transplacental infection of the developing fetus can lead to malformations of varying severity. To assess seroprevalence of SBV in Sweden an indirect enzyme-linked immunosorbent assay (ELISA) was established in connection with the surveys. Here, we describe the development and evaluation of the indirect ELISA, based on whole virus as the coating antigen and a monoclonal antibody for the detection of antibodies to SBV in ruminant sera. The evaluation includes comparison between the in-house ELISA, virus neutralization test and an indirect commercial ELISA.
  
  
  RESULTS
  The optimal working dilutions of antigens and conjugate were estimated with checkerboard titrations. Comparative studies, including ROC analyses, were used for the selection of an optimal cut-off (S/P value = sample value as percentage of positive control value). With an estimated S/P value of 15% the whole virus ELISA showed a specificity of 100% and a sensitivity of 99.19% compared to virus neutralization test (VNT) and with a good consistency as shown in reproducibility and variability experiments. Furthermore, the comparison of our whole virus indirect ELISA to an indirect ELISA with a SBV nucleoprotein antigen, demonstrated a higher sensitivity of our test.
  
  
  CONCLUSIONS
  The indirect whole virus ELISA described in this paper is a readily available test for serological analysis of SBV antibodies. Since this in-house ELISA demonstrates a specificity and sensitivity comparable to virus neutralization test and also shows a higher sensitivity compared to commercially available indirect ELISA, it is a useful alternative for surveillance and screening purposes of SBV.
authors.affiliation: Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, SE-75189, Uppsala, Sweden. katarina.naslund@sva.se.
authors.forename: Katarina
authors.initials: K
authors.lastname: Näslund
authors.affiliation: Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, SE-75189, Uppsala, Sweden. gunilla.blomqvist@sva.se.
authors.forename: Gunilla
authors.initials: G
authors.lastname: Blomqvist
authors.affiliation: Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, SE-75189, Uppsala, Sweden. Caroline.Vernersson@sva.se.
authors.forename: Caroline
authors.initials: C
authors.lastname: Vernersson
authors.affiliation: Virology Unit, French Agency for Food Environmental and Occupational Health Safety, F-94703, Maisons-Alfort, France. szientara@vet-alfort.fr.
authors.forename: Stéphan
authors.initials: S
authors.lastname: Zientara
authors.affiliation: Virology Unit, French Agency for Food Environmental and Occupational Health Safety, F-94703, Maisons-Alfort, France. Emmanuel.BREARD@anses.fr.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Bréard
authors.affiliation: Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, SE-75189, Uppsala, Sweden. jf.valarcher@sva.se.
authors.forename: Jean F
authors.initials: JF
authors.lastname: Valarcher
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000097:blood; D002044:Bunyaviridae Infections / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D015511:Goat Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D006041:Goats; D016851:Orthobunyavirus / Q000302:isolation & purification*; D015995:Prevalence; D015203:Reproducibility of Results; D016036:Seroepidemiologic Studies; D012756:Sheep; D012757:Sheep Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D013548:Sweden / Q000453:epidemiology
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral