Preliminary evaluation of diagnostic accuracy and precision of a competitive ELISA for detection of antibodies to Rift Valley fever virus in cattle and sheep sera

Abstract

Rift Valley fever virus (RVFV), a mosquito-borne, zoonotic pathogen, is endemic to sub-Saharan Africa and has spread beyond the continent to the Arabian Peninsula. The high likelihood of RVFV's spread to other non-endemic countries spurs the need for development and implementation of rapid diagnostic tests and surveillance programs. In this preliminary evaluation, we assessed the diagnostic accuracy and precision of a recombinant RVFV nucleoprotein based competitive ELISA (cELISA) assay to detect RVFV antibodies compared to a plaque reduction neutralization test (PRNT), using sera of cattle and sheep that were experimentally infected with either the MP-12 RVFV vaccine or a wild-type RVFV strain, as well as using known RVFV negative sera. With the manufacturer recommended 60% inhibition for the cELISA and a 1:40 titer for the PRNT, the sensitivity and specificity of the cELISA assay was determined to be 95.1% (95% CI = 83.5-99.4%) and 91.8% (95% CI = 85.0-96.2%), respectively. Antibodies to RVFV were first detected at 5 days post inoculation (dpi) in both species' sera. The prototype cELISA is an easy to implement, sensitive, specific, and safe test for the detection of antibodies to RVFV that can be used in surveillance programs.

Large-Scale International Validation of an Indirect ELISA Based on Recombinant Nucleocapsid Protein of Rift Valley Fever Virus for the Detection of IgG Antibody in Domestic Ruminants

“…The diagnostic accuracy estimates determined in our study are similar to those previously published for ELISAs based on a whole RVFV antigen [36][37][38][39][40][41]55] as well as those based on recombinant NP ELISAs [51][52][53][54][55][56][57][58][59][60], including the commercially available NP-based competition ELISAs [52,60]. Although recorded at a relatively low rate, false-positive results were documented in this study across different subpopulations and are of particular concern in ruminants originating from RVF-non-endemic countries.…”

“…The inhibition ELISA based on a whole tissue culture-derived, inactivated antigen [ 40 ] and competitive ELISA based on recombinant NP antigen [ 50 , 51 , 52 ] allow multi-species RVFV antibody detection using the same diagnostic procedure without requirements for species-specific conjugates. While in the last 15 years, several groups have developed and evaluated various ELISA formats based on RVFV recombinant NP antigen [ 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ], more extensive evaluation of their diagnostic performance was only achieved in humans [ 58 ], buffalo [ 59 ], and cattle [ 60 ] to date.…”

Comparison of Two Rift Valley Fever Serological Tests in Cameroonian Cattle Populations Using a Bayesian Latent Class Approach

“…Our results suggest that in this population it may perform less well but may be a better reflection of performance in a naturally infected population where we do not know the stage of infection and their is a wider range of infectious doses. Other ELISA tests are available including another competitive ELISA produced by Veterinary Medicine Research and Development (Washington State) which when compared to the PRNT 80 had similar sensitivities and specificities (36).…”

“…This represents the first report of estimating the ID.Vet RVF ELISA performance in an African cattle population and the ELISA shows great potential as a low cost easy to use surveillance tool with very good overall accuracy comparable to the more standardized PRNT 80 . Although generally considered the reference test and widely used in reference laboratories the PRNT 80 is labor-intensive, time consuming, expensive, and requires virus appropriate biocontainment (36) and so it not practical for most surveillance activities particularly in LMICs. Laboratories with only very basic equipment can use the kit making it very appropriate for use in Africa.…”

Development of a Visible Reverse Transcription-Loop-Mediated Isothermal Amplification Assay for the Detection of Rift Valley Fever Virus

“…Highly sensitive PCR assays for the detection and quantification of RVFV have been reported, including reverse transcriptase PCR (Garcia et al, 2001;Sall et al, 2002) and real-time RT-PCR (Drosten et al, 2002;Tercero et al, 2019), which require sophisticated equipped laboratories and might be beyond the resources and capabilities of many developing countries. Research on other diagnostic methods has been reported, including optical fiber immunosensor (OFIS), competitive ELISA (Upreti et al, 2018), lateral flow tests (LFT; Cetre-Sossah et al, 2019), fluorescence microsphere immunoassay (FMIA; Ragan et al, 2018), and reverse transcription recombinase polymerase amplification assay (RT-RPA; Euler et al, 2012). The above methods either have low sensitivity, stringent precision requirements and high requirements on operators or present high cost disadvantages.…”