A multiplex fluorescent microsphere immunoassay for increased understanding of Rift Valley fever epidemiology in ruminants in Kenya

Authors: LINDAHL, JOHANNA - International Livestock Research Institute (ILRI) - Kenya; RAGAN, ISABELA - Colorado State University; ROWLAND, RAYMOND - Kansas State University; WAINAINA, MARTIN - International Livestock Research Institute (ILRI) - Kenya; MBOTHA, DEBORAH - International Livestock Research Institute (ILRI) - Kenya; Wilson, William - Bill

Submitted to: PLOS Neglected Tropical Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2019
Publication Date: 4/8/2019
Citation: Lindahl, J., Ragan, I., Rowland, R., Wainaina, M., Mbotha, D., Wilson, W.C. 2019. A multiplex fluorescent microsphere immunoassay for increased understanding of Rift Valley fever epidemiology in ruminants in Kenya. PLOS Neglected Tropical Diseases. https://doi.org/10.1016/j.jviromet.2019.04.011.
DOI: https://doi.org/10.1016/j.jviromet.2019.04.011

Interpretive Summary: The Agricultural Research Service (ARS) is working to develop tools for early detection of introduction of pathogens that would have significant negative impact on US livestock industry. Rift Valley fever virus is endemic in Sub-Saharan Africa which an introduction would have significant impact on ruminant health. Previously, ARS developed a test to detect antibodies to multiple proteins in this virus to provide a sensitive but very specific assay. This paper reports the evaluation of this assay using samples from ruminants in Kenya. The results indicated that the assay can be added to a larger ruminant disease panel for simultaneously screening several abortive and zoonotic pathogens.

Technical Abstract: Rift Valley fever virus (RVFV) is an important mosquito-borne pathogen with devastating impacts on agriculture and public health. With outbreaks being reported beyond the continent of Africa to the Middle East, there is great concern that RVFV will continue to spread to non-endemic areas such as North America and Europe. There is a need for safe and high throughput serological assays for rapid detection of RVFV during outbreaks and for surveillance. We evaluate a multiplexing fluorescent microsphere immunoassay (FMIA) for the detection of IgG and IgM antibodies in ruminant sera against the RVFV nucleocapsid Np, glycoprotein Gn, and non-structural protein NSs. Sheep and cattle sera from a region in Kenya with previous outbreaks were tested by FMIA and two commercially available competitive ELISAs (BDSL and ID-Vet). Our results revealed strong detection of RVFV antibodies against the N, Gn and NSs antigen targets. Additionally, testing of samples with FMIA Np and Gn had 100% agreement with the ID-Vet ELISA. The targets developed in the FMIA assay can be added to a larger ruminant disease panel that can simultaneously screen several abortive and zoonotic pathogens.