title: An inhibition enzyme-linked immunosorbent assay for the detection of antibody to Rift Valley fever virus in humans, domestic and wild ruminants.
abstract: This paper describes the development and validation of an inhibition ELISA based on gamma-irradiated tissue culture-derived antigen for the detection of antibody to Rift Valley fever virus (RVFV) in humans, domestic and wild ruminants. Validation data sets derived from field-collected sera in Africa (humans=1367, cattle=649, goats=806, sheep=493, buffalo=258, camels=156) were categorized according to the results of a virus neutralisation test. In addition, individual sera from 93 laboratory workers immunized with inactivated RVF vaccine, 136 serial bleeds from eight sheep experimentally infected with wild-type of RVFV, and 200 serial bleeds from 10 sheep vaccinated with the live-attenuated strain of the virus, were used to study the kinetics of RVFV antibody production under controlled conditions. At cut-off values selected at 95% accuracy level by the two-graph receiver operating characteristic analysis the ELISA sensitivity ranged from 99.47% (humans) to 100% (sheep, buffalo, camels). The specificity ranged from 99.29% (sheep) to 100% (camels). Compared to virus neutralisation and haemagglutination-inhibition tests, the ELISA was more sensitive in detection of the earliest immunological responses in experimentally infected and vaccinated sheep. Our results demonstrate that the ELISA format reported here can be used as a safe, robust and highly accurate diagnostic tool in disease-surveillance and control programmes, import/export veterinary certification, and for monitoring of the immune response in vaccinees.
authors.affiliation: Special Pathogens Unit, National Institute for Communicable Diseases, Private Bag X4, Sandringham 2131, South Africa. januszp@nicd.ac.za
authors.forename: Janusz T
authors.initials: JT
authors.lastname: Paweska
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Mortimer
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Leman
authors.forename: Robert
authors.initials: R
authors.lastname: Swanepoel
mesh_terms: D000349:Africa / Q000453:epidemiology; D000818:Animals; D000829:Animals, Domestic / Q000097:blood*; D000835:Animals, Wild / Q000097:blood*; D000914:Antibodies, Viral / Q000097:blood*; D002020:Buffaloes; D002162:Camelus; D002417:Cattle; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods* / Q000662:veterinary; D006041:Goats; D006801:Humans; D008403:Mass Screening; D015995:Prevalence; D012295:Rift Valley Fever / Q000453:epidemiology / Q000662:veterinary; D012296:Rift Valley fever virus / Q000276:immunology / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D012756:Sheep; D014611:Vaccination
chemical_list: D000914:Antibodies, Viral